Post-traumatic stress, depression, and anxiety during the 2021 Myanmar conflict: a nationwide population-based survey

Background

The UN warns that Myanmar faces the 'triple crises' of mass conflict, uncontrolled COVID-19, and economic collapse. Therefore, we aimed to assess the population mental health burden, healthcare needs, and the associated risk factors in Myanmar.

Methods

We established a nationwide random sample and recruited 1038 adults via random digit dialling from July 3-Aug 9, 2021, during the ongoing conflict since Feb 1, 2021, and surge in SARS-CoV-2 infections. Probable post-traumatic stress disorder (PTSD) was assessed using the PTSD Checklist-Civilian Version. Probable depression and anxiety were assessed using the Patient Health Questionnaire-2 and the Generalized Anxiety Disorder-2. We calculated population attributable fractions for probable mental disorders using multivariable logistic regression models. Based on the mental health burden and healthcare-seeking patterns, we projected the need for mental health services.

Findings

During the 'triple crises', a third of adults in Myanmar (34.9%, 95% CI 32.0-37.7) reported a probable mental disorder. Prevalence of probable PTSD, depression, and anxiety were 8.1% (6.6-9.7), 14.3% (12.0-16.6), and 22.2% (19.7-24.7), respectively. We estimated that up to 79.9% (43.8-97.9) of probable PTSD was attributable to political stress. This corresponds to 2.1 million (1.1-3.2 million) fewer adults with probable PTSD if political stress was removed from the population. The mental health burden could translate into roughly 5.9 million adults seeking mental health services.

Interpretation

The mental health burden in Myanmar is substantial, and population mental health might only be restored when the three crises have ended. An accelerated peace process is critical to protecting Myanmar's population mental health.

Funding

This research was supported the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. HKU 17606122) and the Michele Tansella Award.

Tracking diarrhea viruses and mpox virus using the wastewater surveillance network in Hong Kong

The wastewater surveillance network successfully established for COVID-19 showed great potential to monitor other infectious viruses, such as norovirus, rotavirus and mpox virus. In this study, we established and validated detection methods for these viruses in wastewater. We developed a supernatant-based method to detect RNA viruses from wastewater samples and applied it to the monthly diarrhea viruses (norovirus genogroup I & II, and rotavirus) surveillance in wastewater treatment plants (WWTPs) at a city-wide level for 16 months. Significant correlations were observed between the diarrhea viruses concentrations in wastewater and detection rates in faecal specimens by clinical surveillance. The highest norovirus concentration in wastewater was obtained in winter, consistent with the seasonal pattern of norovirus outbreak in Hong Kong. Additionally, we established a pellet-based method to monitor DNA viruses in wastewater and detected weak signals for mpox virus in wastewater from a WWTP serving approximately 16,700 people, when the first mpox patient in Hong Kong was admitted to the hospital within the catchment area. Genomic sequencing provided confirmatory evidence for the validity of the results. Our findings emphasized the efficacy of the wastewater surveillance network in WWTPs as a cost-effective tool to track the transmission trend of diarrhea viruses and to provide sensitive detection of novel emerging viruses such as mpox virus in low-prevalence areas. The developed methods and surveillance results provide confidence for establishing robust wastewater surveillance programs to control infectious diseases in the post-pandemic era.

Early-life exposure to ambient air pollutants and kidney function in adolescents: a cohort study based on the 'Children of 1997' Hong Kong birth cohort

OBJECTIVES

Air pollution is increasingly linked to impaired kidney function in adults. However, little is known about how early-life exposure to air pollutants affects kidney function in adolescents.

STUDY DESIGN

Cohort study.

METHODS

We leveraged data from the 'Children of 1997' Hong Kong population-representative birth cohort (N = 8327). Residential exposure to average ambient levels of four air pollutants, including inhalable particle (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), and nitrogen monoxide (NO), during in utero, infancy, and childhood periods was estimated using the inverse distance weighting. Kidney function was assessed using estimated glomerular filtration rate (eGFR) calculated from age-adjusted equations for adolescents. Generalized linear regression was used to examine the association of air pollutant exposure in each period with kidney function at 17.6 years. Two-pollutant models tested the robustness of the association.

RESULTS

Of the 3350 participants included, 51.4% were boys. Exposure to PM10 was associated with poorer kidney function. Each interquartile range increment in PM10 was inversely associated with eGFR (β: -2.933, 95% confidence interval -4.677 to -1.189) in utero, -2.362 (-3.992 to -0.732) infancy, -2.708 (-4.370 to -1.047) childhood, and -2.828 (-4.409 to -1.247) overall. Exposure to PM10 and SO2in utero had a stronger inverse association with kidney function in males. The associations were robust to PM10 exposure in two-pollutant models.

CONCLUSIONS

Our findings suggest that early-life exposure to ambient PM10 and SO2 is associated with reduced kidney function in adolescents, especially exposure in utero.

Early-life exposure to ambient air pollution with cardiovascular risk factors in adolescents: Findings from the "Children of 1997" Hong Kong birth cohort

BACKGROUND

Long-term exposure to ambient air pollution is associated with cardiovascular disease (CVD) risk. Little is known about the impact of early-life exposure to air pollutants on CVD risk factors in late adolescence, which may track into adulthood. To clarify, we examined this question in a unique setting with high air pollution and a high level of economic development.

METHODS

This study leveraged the "Children of 1997" Hong Kong birth cohort (N = 8327), including here 3350 participants. We estimated ambient air pollutant exposure including inhalable particulate matter (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2) and nitrogen monoxide (NO) by growth phase (in utero, infancy, childhood) and overall based on residential address. Generalized linear regression was used to assess the associations of air pollutants exposure by growth phase and sex with CVD risk factors (fasting blood glucose, glycosylated hemoglobin, lipid profile, blood pressure, and body mass index) at 17.6 years. We also assessed whether associations varied by sex.

RESULTS

Early life exposed had little association with glucose metabolism, blood pressure or body mass index, but after considering multiple comparisons early exposure to PM10 was associated with low density lipoprotein (LDL) in boys, with β and 95 % confidence intervals (95 % CI) of 0.184 (0.069 to 0.298) mmol/l, 0.151 (0.056 to 0.248) mmol/l, and 0.157 (0.063 to 0.252) mmol/l by per interquartile range (IQR) increment of PM10 for in utero, infancy, and overall, respectively. No such associations were evident for girls, differences by sex were evident.

CONCLUSIONS

Our study suggested sex-specific associations of early-life PM10 exposure with elevated LDL in adolescence, especially exposure in utero and infancy.

Influenza antibody breadth and effector functions are immune correlates from acquisition of pandemic infection of children

Cross-reactive antibodies with Fc receptor (FcR) effector functions may mitigate pandemic virus impact in the absence of neutralizing antibodies. In this exploratory study, we use serum from a randomized placebo-controlled trial of seasonal trivalent influenza vaccination in children (NCT00792051) conducted at the onset of the 2009 H1N1 pandemic (pH1N1) and monitored for infection. We found that seasonal vaccination increases pH1N1 specific antibodies and FcR effector functions. Furthermore, prospective baseline antibody profiles after seasonal vaccination, prior to pH1N1 infection, show that unvaccinated uninfected children have elevated ADCC effector function, FcγR3a and FcγR2a binding antibodies to multiple pH1N1 proteins, past seasonal and avian (H5, H7 and H9) strains. Whereas, children that became pH1N1 infected after seasonal vaccination have antibodies focussed to seasonal strains without FcR functions, and greater aggregated HA-specific profiles for IgM and IgG3. Modeling to predict infection susceptibility, ranked baseline hemagglutination antibody inhibition as the highest contributor to lack of pH1N1 infection, in combination with features that include pH1-IgG1, H1-stem responses and FcR binding to seasonal vaccine and pH1 proteins. Thus, seasonal vaccination can have benefits against pandemic influenza viruses, and some children already have broadly reactive antibodies with Fc potential without vaccination and may be considered 'elite influenza controllers'.

Decreased risk of non-influenza respiratory infection after influenza B virus infection in children

Previous studies suggest that influenza virus infection may provide temporary non-specific immunity and hence lower the risk of non-influenza respiratory virus infection. In a randomized controlled trial of influenza vaccination, 1 330 children were followed-up in 2009-2011. Respiratory swabs were collected when they reported acute respiratory illness and tested against influenza and other respiratory viruses. We used Poisson regression to compare the incidence of non-influenza respiratory virus infection before and after influenza virus infection. Based on 52 children with influenza B virus infection, the incidence rate ratio (IRR) of non-influenza respiratory virus infection after influenza virus infection was 0.47 (95% confidence interval: 0.27-0.82) compared with before infection. Simulation suggested that this IRR was 0.87 if the temporary protection did not exist. We identified a decreased risk of non-influenza respiratory virus infection after influenza B virus infection in children. Further investigation is needed to determine if this decreased risk could be attributed to temporary non-specific immunity acquired from influenza virus infection.

Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

BACKGROUND

Underweight and obesity are associated with adverse health outcomes throughout the life course. We estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from 1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories.

METHODS

We used data from 3663 population-based studies with 222 million participants that measured height and weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children and adolescents (age 5-19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the individual and combined prevalence of underweight (BMI <18·5 kg/m2) and obesity (BMI ≥30 kg/m2). For school-aged children and adolescents, we report thinness (BMI <2 SD below the median of the WHO growth reference) and obesity (BMI >2 SD above the median).

FINDINGS

From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in 11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and 140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%) with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and 42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents, the increases in double burden were driven by increases in obesity, and decreases in double burden by declining underweight or thinness.

INTERPRETATION

The combined burden of underweight and obesity has increased in most countries, driven by an increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of underweight while curbing and reversing the increase in obesity.

FUNDING

UK Medical Research Council, UK Research and Innovation (Research England), UK Research and Innovation (Innovate UK), and European Union.

Nirmatrelvir/ritonavir use in pregnant women with SARS-CoV-2 Omicron infection: a target trial emulation

To date, there is a lack of randomized trial data examining the use of the antiviral nirmatrelvir/ritonavir in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected pregnant persons. This target trial emulation study aimed to address this gap by evaluating the use of nirmatrelvir/ritonavir in nonhospitalized pregnant women with symptomatic SARS-CoV-2 Omicron variant infection. Among patients diagnosed between 16 March 2022 and 5 February 2023, exposure was defined as outpatient nirmatrelvir/ritonavir treatment within 5 days of symptom onset or coronavirus disease 2019 (COVID-19) diagnosis. Primary outcomes were maternal morbidity and mortality index (MMMI), all-cause maternal death and COVID-19-related hospitalization, while secondary outcomes were individual components of MMMI, preterm birth, stillbirth, neonatal death and cesarean section. One-to-ten propensity-score matching was conducted between nirmatrelvir/ritonavir users and nonusers, followed by cloning, censoring and weighting. Overall, 211 pregnant women on nirmatrelvir/ritonavir and 1,998 nonusers were included. Nirmatrelvir/ritonavir treatment was associated with reduced 28-day MMMI risk (absolute risk reduction (ARR) = 1.47%, 95% confidence interval (CI) = 0.21-2.34%) but not 28-days COVID-19-related hospitalization (ARR = -0.09%, 95% CI = -1.08% to 0.71%). Nirmatrelvir/ritonavir treatment was also associated with reduced risks of cesarean section (ARR = 1.58%, 95% CI = 0.85-2.39%) and preterm birth (ARR = 2.70%, 95% CI = 0.98-5.31%). No events of maternal or neonatal death or stillbirth were recorded. The findings suggest that nirmatrelvir/ritonavir is an effective treatment in symptomatic pregnant women with SARS-CoV-2 Omicron variant infection.

Optimal timing of nirmatrelvir/ritonavir treatment after COVID-19 symptom onset or diagnosis: target trial emulation

Reports of symptomatic rebound and/or test re-positivity among COVID-19 patients following the standard five-day treatment course of nirmatrelvir/ritonavir have sparked debates regarding optimal treatment timing and dosage. It is unclear whether initiating nirmatrelvir/ritonavir immediately after symptom onset would improve clinical outcomes and/or lead to post-treatment viral burden rebound due to inadequate viral clearance during treatment. Here we show that, by emulating a randomized target trial using real-world electronic medical record data from all 87,070 adult users of nirmatrelvir/ritonavir in Hong Kong between 16th March 2022 and 15th January 2023, early initiation of nirmatrelvir/ritonavir treatment (0 to 1 days after symptom onset or diagnosis) significantly reduced the incidence of 28-day all-cause mortality and hospitalization compared to delayed initiation (2 or more days) (absolute risk reduction [ARR]: 1.50% (95% confidence interval 1.17-1.80%); relative risk [RR]: 0.77 (0.73, 0.82)), but may be associated with a significant elevated risk of viral burden rebound (ARR: -1.08% (-1.55%, -0.46%)), although the latter estimates were associated with high uncertainty due to limited sample sizes. As such, patients should continue to initiate nirmatrelvir/ritonavir early after symptom onset or diagnosis to better protect against the more serious outcomes of hospitalization and mortality.

Risk of acute liver injury following the nirmatrelvir/ritonavir use

BACKGROUND

Elevations in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were reported as adverse events of nirmatrelvir/ritonavir users in the EPIC-HR trial.

AIM

To quantify the risk and severity of acute liver injury (ALI) associated with nirmatrelvir/ritonavir use.

METHODS

This self-controlled case-series study was conducted using electronic medical records of patients with confirmed diagnosis of SARS-CoV-2 infection between 26th February 2022 and 12th February 2023 in Hong Kong.

RESULTS

Among 2 409 848 patients with SARS-CoV-2 infection during the study period, 153 853 were prescribed with nirmatrelvir/ritonavir, of whom 834 (.5%) had incident ALI (moderate: 30.5%; moderate to severe: 18.9%; severe or fatal: 5.8%). Compared with the non-exposure period, risk of ALI increased significantly during the pre-exposure period (IRR = 38.13, 95% CI = 29.29-49.62) and remained elevated during the five-day nirmatrelvir/ritonavir treatment (IRR = 20.75, 95% CI = 17.06-25.25) and during wash-out period (IRR = 16.27, 95% CI = 13.23-20.01). Compared to the pre-exposure period, risk of ALI was not increased during the five-day nirmatrelvir/ritonavir treatment period (IRR = .54, 95% CI = .43-.70). Compared to 5469 non-nirmatrelvir/ritonavir users with incident ALI, nirmatrelvir/ritonavir users had less severe ALI by the severity index (p < .001) and peak INR (1.7 vs. 2.3; p < .001). ALI cases with nirmatrelvir/ritonavir use had lower risk of all-cause death (29.1% vs. 39.1%; OR = .64; p < .001) and no increase in risk of liver decompensation (1.0% vs. 1.3%; OR = .62; p = .230) compared to non-users.

CONCLUSION

The risk of ALI associated with nirmatrelvir/ritonavir treatment for COVID-19 was elevated in the pre-exposure period, but not following nirmatrelvir/ritonavir initiation. ALI following nirmatrelvir/ritonavir treatment were mostly mild and less severe than ALI events in non-nirmatrelvir/ritonavir users.

Contributions of residential traffic noise to depression and mental wellbeing in Hong Kong: A prospective cohort study

Prior studies on the association between traffic noise and mental health have been mostly conducted in settings with lower population densities. However, evidence is lacking in high population-density settings where traffic noise is more pervasive and varies by topography and the vertical elevation of the residential unit. This study aimed to assess the mental health impact of residential traffic noise in one of the world's most urbanised populations. Data were analysed from 13,401 participants aged ≥15 years in a prospective cohort in Hong Kong from 2009 to 2014. Residential traffic noise level was estimated using 3D-geocoding and validated models that accounted for sound propagation in a highly vertical landscape. The 24-h day-night exposure to traffic noise, denoted as Ldn, was estimated with a 10-dB(A) penalty for night hours. Probable depression and mental wellbeing were assessed using the Patient Health Questionnaire-9 and the Short Form Health Questionnaire SF-12v2, respectively. Mixed effect regressions with random intercepts were used to examine the association between traffic noise and mental health outcomes. Residential road traffic noise (for each increment of 10 A-weighted decibels [dB(A)] 24-h average exposure) was associated with probable depression (odds ratio (OR) = 1.17, 95% CI: 1.05, 1.31), and poorer mental wellbeing (mean difference = -0.19, 95% CI: 0.31, -0.06), adjusting for sociodemographics, smoking, body mass index, self-reported health, proximity to green space, and neighbourhood characteristics (average household income, population density, and Gini coefficient). The results were robust to further adjustment for air pollution. In stratified analyses, residential traffic noise was associated with probable depression and poorer mental wellbeing among students and individuals aged 15-34 years. Residential traffic noise was associated with probable depression and poorer mental wellbeing in a highly urbanised setting. As traffic noise is increasing in urban settings, the public health impact of noise pollution could be substantial.

Global variation in diabetes diagnosis and prevalence based on fasting glucose and hemoglobin A1c

Fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) are both used to diagnose diabetes, but these measurements can identify different people as having diabetes. We used data from 117 population-based studies and quantified, in different world regions, the prevalence of diagnosed diabetes, and whether those who were previously undiagnosed and detected as having diabetes in survey screening, had elevated FPG, HbA1c or both. We developed prediction equations for estimating the probability that a person without previously diagnosed diabetes, and at a specific level of FPG, had elevated HbA1c, and vice versa. The age-standardized proportion of diabetes that was previously undiagnosed and detected in survey screening ranged from 30% in the high-income western region to 66% in south Asia. Among those with screen-detected diabetes with either test, the age-standardized proportion who had elevated levels of both FPG and HbA1c was 29-39% across regions; the remainder had discordant elevation of FPG or HbA1c. In most low- and middle-income regions, isolated elevated HbA1c was more common than isolated elevated FPG. In these regions, the use of FPG alone may delay diabetes diagnosis and underestimate diabetes prevalence. Our prediction equations help allocate finite resources for measuring HbA1c to reduce the global shortfall in diabetes diagnosis and surveillance.

Assessing the safety of lipid-modifying medications among Chinese adolescents: a drug-target Mendelian randomization study

BACKGROUND

With increasing hypercholesterolemia prevalence in East Asian adolescents, pharmacologic interventions (e.g., HMGCR inhibitors (statins) and PCSK9 inhibitors) may have to be considered although their longer-term safety in the general adolescent population is unclear. This study aims to investigate the longer-term safety of HMGCR inhibitors and PCSK9 inhibitors among East Asian adolescents using genetics.

METHODS

A drug-target Mendelian randomization study leveraging the Global Lipid Genetics Consortium (East Asian, n = 146,492) and individual-level data from Chinese participants in the Biobank clinical follow-up of Hong Kong's "Children of 1997" birth cohort (n = 3443, aged ~ 17.6 years). Safety outcomes (n = 100) included anthropometric and hematological traits, renal, liver, lung function, and other nuclear magnetic resonance metabolomics. Positive control outcomes were cholesterol markers from the "Children of 1997" birth cohort and coronary artery disease from Biobank Japan.

RESULTS

Genetic inhibition of HMGCR and PCSK9 were associated with reduction in cholesterol-related NMR metabolomics, e.g., apolipoprotein B (HMGCR: beta [95% CI], - 1.06 [- 1.52 to - 0.60]; PCSK9: - 0.93 [- 1.56 to - 0.31]) and had the expected effect on the positive control outcomes. After correcting for multiple comparisons (p-value < 0.006), genetic inhibition of HMGCR was associated with lower linoleic acid - 0.79 [- 1.25 to - 0.35]. Genetic inhibition of PCSK9 was not associated with the safety outcomes assessed.

CONCLUSIONS

Statins and PCSK9 inhibitors in East Asian adolescents appeared to be safe based on the outcomes concerned. Larger studies were warranted to verify these findings. This study serves as a proof of principle study to inform the medication safety among adolescents via genetics.

Development and application of influenza virus wastewater surveillance in Hong Kong

Wastewater surveillance is considered as a powerful tool in providing cost-effective, population-wide and near real-time surveillance results for controlling infectious diseases (i.e., SARS-CoV-2, influenza virus), complementary to clinical surveillance. To facilitate the utility of this emerging tool, we developed two preanalytical protocols (supernatant-based and pellet-based) for influenza A/B virus (IAV/IBV) wastewater surveillance and applied them to the established wastewater surveillance network for large-scale longitudinal monitoring in Hong Kong. We tested 724 wastewater samples from 24 stationary sites for weekly surveillance for 8 months and 458 wastewater samples from 11 wastewater treatment plants (WWTPs) for more frequent (three times per week) city-wide surveillance for 4 months when influenza season commenced. We found the city-wide IAV virus concentration in wastewater were associated with the detection rate and influenza-like illness plus rates (ILI+) of clinical respiratory specimens and increased significantly after the cancelling of mask mandate that was in place for COVID-19. IBV was at low detection rates and low virus concentration levels, consistent with the low detection rates observed by clinical surveillance. In addition, we conducted virus subtype identification in selected wastewater samples, and observed the H1pdm was the major circulation subtype. Moreover, the obtained virus signals were confirmed by Sanger sequencing of PCR products, suggesting the feasibility and applicability of established methods for rapid detection of influenza virus types and subtypes in wastewater surveillance. This study demonstrates the applicability of IAV/IBV wastewater surveillance to current wastewater infrastructures and it could be used as a rapid and cost-effective surveillance strategy to track virus transmission patterns in the community for timely public health actions in the future.

COVID-19 Vaccination Willingness and Reasons for Vaccine Refusal

Importance

Hong Kong was held as an exemplar for pandemic response until it recorded the world's highest daily COVID-19 mortality, which was likely due to vaccine refusal. To prevent this high mortality in future pandemics, information on underlying reasons for vaccine refusal is necessary.

Objectives

To track the evolution of COVID-19 vaccination willingness and uptake from before vaccine rollout to mass vaccination, to examine factors associated with COVID-19 vaccine refusal and compare with data from Singapore, and to assess the population attributable fraction for vaccine refusal.

Design, Setting, and Participants

This cohort study used data from randomly sampled participants from 14 waves of population-based studies in Hong Kong (February 2020 to May 2022) and 2 waves of population-based studies in Singapore (May 2020 to June 2021 and October 2021 to January 2022), and a population-wide registry of COVID-19 vaccination appointments. Data were analyzed from February 23, 2021, to May 30, 2022.

Exposures

Trust in COVID-19 vaccine information sources (ie, health authorities, physicians, traditional media, and social media); COVID-19 vaccine confidence on effectiveness, safety, and importance; COVID-19 vaccine misconceptions on safety and high-risk groups; political views; and COVID-19 policies (ie, workplace vaccine mandates and vaccine pass).

Main Outcomes and Measures

Primary outcomes were the weighted prevalence of COVID-19 vaccination willingness over the pandemic, adjusted incidence rate ratios, and population attributable fractions of COVID-19 vaccine refusal. A secondary outcome was change in daily COVID-19 vaccination appointments.

Results

The study included 28 007 interviews from 20 waves of longitudinal data, with 1114 participants in the most recent wave (median [range] age, 54.2 years [20-92] years; 571 [51.3%] female). Four factors-mistrust in health authorities, low vaccine confidence, vaccine misconceptions, and political views-could jointly account for 82.2% (95% CI, 62.3%-100.0%) of vaccine refusal in adults aged 18 to 59 years and 69.3% (95% CI, 47.2%-91.4%) of vaccine refusal in adults aged 60 years and older. Workplace vaccine mandates were associated with 62.2% (95% CI, 9.9%-139.2%) increases in daily COVID-19 vaccination appointments, and the Hong Kong vaccine pass was associated with 124.8% (95% CI, 65.9%-204.6%) increases in daily COVID-19 vaccination appointments.

Conclusions and Relevance

These findings suggest that trust in health authorities was fundamental to overcoming vaccine hesitancy. As such, engendering trust in health care professionals, experts, and public health agencies should be incorporated into pandemic preparedness and response.

Comparative antibody and cell-mediated immune responses, reactogenicity, and efficacy of homologous and heterologous boosting with CoronaVac and BNT162b2 (Cobovax): an open-label, randomised trial

BACKGROUND

Few trials have compared homologous and heterologous third doses of COVID-19 vaccination with inactivated vaccines and mRNA vaccines. The aim of this study was to assess immune responses, safety, and efficacy against SARS-CoV-2 infection following homologous or heterologous third-dose COVID-19 vaccination with either one dose of CoronaVac (Sinovac Biotech; inactivated vaccine) or BNT162b2 (Fosun Pharma-BioNTech; mRNA vaccine).

METHODS

This is an ongoing, randomised, allocation-concealed, open-label, comparator-controlled trial in adults aged 18 years or older enrolled from the community in Hong Kong, who had received two doses of CoronaVac or BNT162b2 at least 6 months earlier. Participants were randomly assigned, using a computer-generated sequence, in a 1:1 ratio with allocation concealment to receive a (third) dose of CoronaVac or BNT162b2 (ancestral virus strain), stratified by types of previous COVID-19 vaccination (homologous two doses of CoronaVac or BNT162b2). Participants were unmasked to group allocation after vaccination. The primary endpoint was serum neutralising antibodies against the ancestral virus at day 28 after vaccination in each group, measured as plaque reduction neutralisation test (PRNT50) geometric mean titre (GMT). Surrogate virus neutralisation test (sVNT) mean inhibition percentage and PRNT50 titres against omicron BA.1 and BA.2 subvariants were also measured. Secondary endpoints included geometric mean fold rise (GMFR) in antibody titres; incidence of solicited local and systemic adverse events; IFNγ+ CD4+ and IFNγ+ CD8+ T-cell responses at days 7 and 28; and incidence of COVID-19. Within-group comparisons of boost in immunogenicity from baseline and between-group comparisons were done according to intervention received (ie, per protocol) by paired and unpaired t test, respectively, and cumulative incidence of infection was compared using Kaplan-Meier curves and a proportional hazards model to estimate hazard ratio. The trial is registered with ClinicalTrials.gov, NCT05057169.

FINDINGS

We enrolled participants from Nov 12, 2021, to Jan 27, 2022. We vaccinated 219 participants who previously received two doses of CoronaVac, including 101 randomly assigned to receive CoronaVac (CC-C) and 118 randomly assigned to receive BNT162b2 (CC-B) as their third dose; and 232 participants who previously received two doses of BNT162b2, including 118 randomly assigned to receive CoronaVac (BB-C) and 114 randomly assigned to receive BNT162b2 (BB-B) as their third dose. The PRNT50 GMTs on day 28 against ancestral virus were 109, 905, 92, and 816; against omicron BA.1 were 9, 75, 8, and 86; and against omicron BA.2 were 6, 80, 6, and 67 in the CC-C, CC-B, BB-C, and BB-B groups, respectively. Mean sVNT inhibition percentages on day 28 against ancestral virus were 83%, 96%, 87%, and 96%; against omicron BA.1 were 15%, 58%, 19%, and 69%; and against omicron BA.2 were 43%, 85%, 50%, and 90%, in the CC-C, CC-B, BB-C, and BB-B groups, respectively. Participants who had previously received two doses of CoronaVac and a BNT162b2 third dose had a GMFR of 12 (p<0·0001) compared with those who received a CoronaVac third dose; similarly, those who had received two doses of BNT162b2 and a BNT162b2 third dose had a GMFR of 8 (p<0·0001). No differences in CD4+ and CD8+ T-cell responses were observed between groups. We did not identify any vaccination-related hospitalisation within 1 month after vaccination. We identified 58 infections when omicron BA.2 was predominantly circulating, with cumulative incidence of 15·3% and 15·4% in the CC-C and CC-B groups, respectively (p=0·93), and 16·7% and 14·0% in the BB-C and BB-B groups, respectively (p=0·56).

INTERPRETATION

Similar levels of incidence of, presumably, omicron BA.2 infections were observed in each group despite very weak antibody responses to BA.2 in the recipients of a CoronaVac third dose. Further research is warranted to identify appropriate correlates of protection for inactivated COVID-19 vaccines.

FUNDING

Health and Medical Research Fund, Hong Kong.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

Sector-Based Regression Strategies to Reduce Refractive Error-Associated Glaucoma Diagnostic Bias When Using OCT and OCT Angiography

Purpose

This cross-sectional study aimed to investigate the sectoral variance of optical coherence tomography (OCT) and OCT angiography (OCTA) glaucoma diagnostic parameters across eyes with varying degrees of refractive error.

Methods

Healthy participants, including individuals with axial ametropia, enrolled in the Hong Kong FAMILY cohort were imaged using the Avanti/AngioVue OCT/OCTA system. The OCT and OCTA parameters obtained include peripapillary nerve fiber layer thickness (NFLT), peripapillary nerve fiber layer plexus capillary density (NFLP-CD), and macular ganglion cell complex thickness (GCCT). Sectoral measurements of NFLT, NFLP-CD, and GCCT were based on sectors and hemispheres.

Results

A total of 1339 eyes from 791 participants were stratified based on spherical equivalent refraction: high myopia (<-6 D), low myopia (-6 D to -1 D), emmetropia (-1 D to 1 D), and hyperopia (>1 D). Multivariable broken stick regression models, accounting for age, sex, and signal strength, showed that all NFLT sectors except temporally, the inferior GCCT hemisphere, and half of the NFLP-CD sectors were more affected by ametropia-related covariates than the corresponding global parameters. As expected, the false-positive rates in those sectors were elevated. Finally, sector-specific axial length (AL) and spherical equivalent (SE) adjustments helped reduce the elevated false-positive rates.

Conclusions

The effect of optical magnification is even more prominent among sectors than the global parameters. AL- and SE-based adjustments should be individualized to each sector to mitigate this magnification bias effectively.

Translational Relevance

Identifying sectoral differences among diagnostic parameters and adopting these sector-based adjustments into commercial OCT systems will hopefully reduce false-positive rates related to refractive error.

Viral kinetics of SARS-CoV-2 following onset of COVID-19 in symptomatic patients infected with the ancestral strain and omicron BA.2 in Hong Kong: a retrospective observational study

BACKGROUND

Assessment of viral kinetics of SARS-CoV-2 can inform on host immune responses to the virus and on the viral transmission potential. We aimed to characterise viral shedding kinetics by age, virus type, and clinical outcome, and to examine the potential effect of vaccination on viral shedding.

METHODS

In this retrospective observational study, we analysed longitudinal data on cycle threshold (Ct) values of reverse-transcription quantitative PCR (RT-qPCR) assays of upper respiratory tract samples from symptomatic patients with COVID-19. Patients who were confirmed with COVID-19 with at least one Ct value of the RT-qPCR test available within 28 days after symptom onset, and discharged or died at the time of the analysis, were included in the study. Patients were isolated in hospitals in Hong Kong during three major epidemic waves dominated by the ancestral strain or omicron BA.2. We modelled the temporal trajectories of viral burden in these patients. Electronic medical records of the patients with COVID-19 were retrieved and linked to the patients' epidemiological information obtained from contact tracing. Patients who were infected outside Hong Kong, infected with variants other than the ancestral strain or omicron BA.2, not reporting any COVID-19 related symptoms, still hospitalised at the time of analysis, missing information on age, time of symptom onset, infection severity, vaccination or clinical outcome, infected more than once, or treated with nirmatrelvir-ritonavir or molnupiravir were excluded from analysis. The main outcome of this study is the temporal change of SARS-CoV-2 viral burden measured by Ct values of RT-qPCR tests in symptomatic patients with COVID-19.

FINDINGS

Among 22 461 symptomatic patients with COVID-19 confirmed from July 1, 2020, to May 22, 2022, the estimated viral burden from a random-effects model indicated a longer duration of viral shedding in patients with more severe outcomes of infection (mean difference 13·1 days, 95% CI 12·9-13·3, for fatal vs mild-to-moderate) and in older patients (5·2, 5·0-5·5, for age ≥80 years vs 0-18 years). Vaccinated individuals with a breakthrough infection with the omicron BA.2 variant had a generally lower viral burden and shorter durations of viral shedding (mean difference of 2-4 days) over 4 weeks after onset than unvaccinated individuals infected with omicron BA.2, particularly in patients whose last dose of COVID-19 vaccine was received ≤90 days before symptom onset. Marginal differences in viral burden following symptom onset and the duration of viral shedding were observed between unvaccinated individuals infected with the ancestral strain and omicron BA.2.

INTERPRETATION

The viral kinetics since symptom onset characterised for symptomatic patients with COVID-19 in our study show that previously vaccinated or younger individuals, or those with a milder infection, shed fewer viruses in a shorter period, implying possible transmission dynamics of SARS-CoV-2 and protective mechanisms of vaccination against infection and severe outcomes.

FUNDING

Hong Kong Health and Medical Research Fund and Hong Kong Collaborative Research Fund.

Residential Clustering of Coronavirus Disease 2019 Cases and Efficiency of Building-Wide Compulsory Testing Notices as a Transmission Control Measure in Hong Kong

We described the frequency of residential case clusters and the efficiency of compulsory testing in identifying cases using buildings targeted in compulsory testing and locally infected coronavirus disease 2019 (COVID-19) cases matched by residence in Hong Kong. Most of the buildings (4246 of 7688, 55.2%) with COVID-19 cases identified had only 1 reported case, and 13% of the daily reported cases were detected through compulsory testing. Compulsory testing notices could be essential in attempting to eliminate infections ("zero COVID") and have an impact early in an epidemic, but they appear to be relatively inefficient in response to sustained community transmission.

Reconstructing household transmission dynamics to estimate the infectiousness of asymptomatic influenza virus infections

There has long been controversy over the potential for asymptomatic cases of the influenza virus to have the capacity for onward transmission, but recognition of asymptomatic transmission of COVID-19 stimulates further research into this topic. Here, we develop a Bayesian methodology to analyze detailed data from a large cohort of 727 households and 2515 individuals in the 2009 pandemic influenza A(H1N1) outbreak in Hong Kong to characterize household transmission dynamics and to estimate the relative infectiousness of asymptomatic versus symptomatic influenza cases. The posterior probability that asymptomatic cases [36% of cases; 95% credible interval (CrI): 32%, 40%] are less infectious than symptomatic cases is 0.82, with estimated relative infectiousness 0.57 (95% CrI: 0.11, 1.54). More data are required to strengthen our understanding of the contribution of asymptomatic cases to the spread of influenza.

Breastfeeding and ApoB in late adolescence: a Hong Kong birth cohort study

Breastfeeding is widely promoted. Experimental evidence concerning long-term benefits is limited. Observational studies are open to bias from confounding by socio-economic position. We assessed the association of breastfeeding with late adolescent lipid sub-fractions, particularly apolipoprotein B (ApoB) and non-high-density lipoprotein cholesterol (non-HDL-c), overall and by sex. We took advantage of a setting where breastfeeding has little association with higher socio-economic position and where several results from randomized controlled trials of breastfeeding promotion have been replicated. We used the population-representative "Children of 1997" birth cohort comprising 88% of births in Hong Kong in April and May 1997. Associations of breastfeeding in the first 3 months of life (never, mixed, exclusive) with lipid sub-fractions were obtained using linear regression adjusted for potential confounders including parental socio-economic position, maternal place of birth, type of delivery, gestational age, and birth weight. Differences by sex were assessed. Multiple imputation and inverse probability weighting were used to recover the original sample. Of the 3462 participants included, mean age was 17.6 years and 48.8% were girls. Mean ApoB was 0.74 g/L (standard deviation 0.15). Exclusive versus never breastfeeding was associated with lower ApoB (-0.027 g/L, 95% confidence interval (CI)-0.046 to-0.007, p = 0.007) and lower non-HDL-c (-0.143 mmol/L, 95% CI-0.237 to-0.048) with similar estimates by sex.

CONCLUSION

Breastfeeding may provide some population-level lifelong protection against cardiovascular disease. This study supports policies promoting breastfeeding as a modifiable exposure that contributes to a healthy start in life as an investment for lifelong cardiovascular disease prevention.

WHAT IS KNOWN

• Apolipoprotein B (ApoB) is a recognized risk factor for cardiovascular disease, but whether breastfeeding affects ApoB in later life overall and by sex is unknown.

WHAT IS NEW

• Exclusive breastfeeding in the first 3 months of life was associated with lower ApoB in late adolescence, with similar estimates for both sexes. • The inverse association of breastfeeding with ApoB suggests that breastfeeding could reduce cardiovascular disease and overall mortality over the lifespan.

Toward a Universal Unit for Quantification of Antibiotic Resistance Genes in Environmental Samples

Surveillance of antibiotic resistance genes (ARGs) has been increasingly conducted in environmental sectors to complement the surveys in human and animal sectors under the "One-Health" framework. However, there are substantial challenges in comparing and synthesizing the results of multiple studies that employ different test methods and approaches in bioinformatic analysis. In this article, we consider the commonly used quantification units (ARG copy per cell, ARG copy per genome, ARG density, ARG copy per 16S rRNA gene, RPKM, coverage, PPM, etc.) for profiling ARGs and suggest a universal unit (ARG copy per cell) for reporting such biological measurements of samples and improving the comparability of different surveillance efforts.

Viral burden rebound in hospitalised patients with COVID-19 receiving oral antivirals in Hong Kong: a population-wide retrospective cohort study

BACKGROUND

Viral rebound after nirmatrelvir-ritonavir treatment has implications for the clinical management and isolation of patients with COVID-19. We evaluated an unselected, population-wide cohort to identify the incidence of viral burden rebound and associated risk factors and clinical outcomes.

METHODS

We did a retrospective cohort study of hospitalised patients with a confirmed diagnosis of COVID-19 in Hong Kong, China, for an observation period from Feb 26 to July 3, 2022 (during the omicron BA.2.2 variant wave). Adult patients (age ≥18 years) admitted 3 days before or after a positive COVID-19 test were selected from medical records held by the Hospital Authority of Hong Kong. We included patients with non-oxygen-dependent COVID-19 at baseline receiving either molnupiravir (800 mg twice a day for 5 days), nirmatrelvir-ritonavir (nirmatrelvir 300 mg with ritonavir 100 mg twice a day for 5 days), or no oral antiviral treatment (control group). Viral burden rebound was defined as a reduction in cycle threshold (Ct) value (≥3) on quantitative RT-PCR test between two consecutive measurements, with such decrease sustained in an immediately subsequent Ct measurement (for those patients with ≥3 Ct measurements). Logistic regression models were used to identify prognostic factors for viral burden rebound, and to assess associations between viral burden rebound and a composite clinical outcome of mortality, intensive care unit admission, and invasive mechanical ventilation initiation, stratified by treatment group.

FINDINGS

We included 4592 hospitalised patients with non-oxygen-dependent COVID-19 (1998 [43·5%] women and 2594 [56·5%] men). During the omicron BA.2.2 wave, viral burden rebound occurred in 16 of 242 patients (6·6% [95% CI 4·1-10·5]) receiving nirmatrelvir-ritonavir, 27 of 563 (4·8% [3·3-6·9]) receiving molnupiravir, and 170 of 3787 (4·5% [3·9-5·2]) in the control group. The incidence of viral burden rebound did not differ significantly across the three groups. Immunocompromised status was associated with increased odds of viral burden rebound, regardless of antiviral treatment (nirmatrelvir-ritonavir: odds ratio [OR] 7·37 [95% CI 2·56-21·26], p=0·0002; molnupiravir: 3·05 [1·28-7·25], p=0·012; control: 2·21 [1·50-3·27], p<0·0001). Among patients receiving nirmatrelvir-ritonavir, the odds of viral burden rebound were higher in those aged 18-65 years (vs >65 years; 3·09 [1·00-9·53], p=0·050), those with high comorbidity burden (score >6 on the Charlson Comorbidity Index; 6·02 [2·09-17·38], p=0·0009), and those concomitantly taking corticosteroids (7·51 [1·67-33·82], p=0·0086); whereas the odds were lower in those who were not fully vaccinated (0·16 [0·04-0·67], p=0·012). In patients receiving molnupiravir, those aged 18-65 years (2·68 [1·09-6·58], p=0·032) or on concomitant corticosteroids (3·11 [1·23-7·82], p=0·016) had increased odds of viral burden rebound. We found no association between viral burden rebound and occurrence of the composite clinical outcome from day 5 of follow-up (nirmatrelvir-ritonavir: adjusted OR 1·90 [0·48-7·59], p=0·36; molnupiravir: 1·05 [0·39-2·84], p=0·92; control: 1·27 [0·89-1·80], p=0·18).

INTERPRETATION

Viral burden rebound rates are similar between patients with antiviral treatment and those without. Importantly, viral burden rebound was not associated with adverse clinical outcomes.

FUNDING

Health and Medical Research Fund, Health Bureau, The Government of the Hong Kong Special Administrative Region, China.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

The city-wide full-scale interactive application of sewage surveillance programme for assisting real-time COVID-19 pandemic control - A case study in Hong Kong

The paper discusses the implementation of Hong Kong's tailor-made sewage surveillance programme led by the Government, which has demonstrated how an efficient and well-organized sewage surveillance system can complement conventional epidemiological surveillance to facilitate the planning of intervention strategies and actions for combating COVID-19 pandemic in real-time. This included the setting up of a comprehensive sewerage network-based SARS-CoV-2 virus surveillance programme with 154 stationary sites covering 6 million people (or 80 % of the total population), and employing an intensive monitoring programme to take samples from each stationary site every 2 days. From 1 January to 22 May 2022, the daily confirmed case count started with 17 cases per day on 1 January to a maximum of 76,991 cases on 3 March and dropped to 237 cases on 22 May. During this period, a total of 270 "Restriction-Testing Declaration" (RTD) operations at high-risk residential areas were conducted based on the sewage virus testing results, where over 26,500 confirmed cases were detected with a majority being asymptomatic. In addition, Compulsory Testing Notices (CTN) were issued to residents, and the distribution of Rapid Antigen Test kits was adopted as alternatives to RTD operations in areas of moderate risk. These measures formulated a tiered and cost-effective approach to combat the disease in the local setting. Some ongoing and future enhancement efforts to improve efficacy are discussed from the perspective of wastewater-based epidemiology. Forecast models on case counts based on sewage virus testing results were also developed with R² of 0.9669-0.9775, which estimated that up to 22 May 2022, around 2,000,000 people (~67 % higher than the total number of 1,200,000 reported to the health authority, due to various constraints or limitations) had potentially contracted the disease, which is believed to be reflecting the real situation occurring in a highly urbanized metropolis like Hong Kong.

Environment- and epigenome-wide association study of obesity in 'Children of 1997' birth cohort

Background

Increasing childhood obesity is a global issue requiring potentially local solutions to ensure it does not continue into adulthood. We systematically identified potentially modifiable targets of obesity at the onset and end of puberty in Hong Kong, the most economically developed major Chinese city.

Methods

We conducted an environment-wide association study (EWAS) and an epigenome-wide association study of obesity to systematically assess associations with body mass index (BMI) and waist-hip ratio (WHR) in Hong Kong's population-representative 'Children of 1997' birth cohort. Univariable linear regression was used to select exposures related to obesity at ~11.5 years (BMI and obesity risk n ≤ 7119, WHR n = 5691) and ~17.6 years (n = 3618) at Bonferroni-corrected significance, and multivariable regression to adjust for potential confounders followed by replicated multivariable regression (n = 308) and CpG by CpG analysis (n = 286) at ~23 years. Findings were compared with evidence from published randomized controlled trials (RCTs) and Mendelian randomization (MR) studies.

Results

At ~11.5 and~17.6 years the EWAS identified 14 and 37 exposures associated with BMI, as well as 7 and 12 associated with WHR, respectively. Most exposures had directionally consistent associations at ~23 years. Maternal second-hand smoking, maternal weight, and birth weight were consistently associated with obesity. Diet (including dairy intake and artificially sweetened beverages), physical activity, snoring, binge eating, and earlier puberty were positively associated with BMI at ~17.6 years, while eating before sleep was inversely associated with BMI at ~17.6 years. Findings for birth weight, dairy intake, and binge eating are consistent with available evidence from RCTs or MR studies. We found 17 CpGs related to BMI and 17 to WHR.

Conclusions

These novel insights into potentially modifiable factors associated with obesity at the outset and the end of puberty could, if causal, inform future interventions to improve population health in Hong Kong and similar Chinese settings.

Funding

This study including the follow-up survey and epigenetics testing was supported by the Health and Medical Research Fund Research Fellowship, Food and Health Bureau, Hong Kong SAR Government (#04180097). The DNA extraction of the samples used for epigenetic testing was supported by CFS-HKU1.

Resurgence of Omicron BA.2 in SARS-CoV-2 infection-naive Hong Kong

Hong Kong experienced a surge of Omicron BA.2 infections in early 2022, resulting in one of the highest per-capita death rates of COVID-19. The outbreak occurred in a dense population with low immunity towards natural SARS-CoV-2 infection, high vaccine hesitancy in vulnerable populations, comprehensive disease surveillance and the capacity for stringent public health and social measures (PHSMs). By analyzing genome sequences and epidemiological data, we reconstructed the epidemic trajectory of BA.2 wave and found that the initial BA.2 community transmission emerged from cross-infection within hotel quarantine. The rapid implementation of PHSMs suppressed early epidemic growth but the effective reproduction number (R_e) increased again during the Spring festival in early February and remained around 1 until early April. Independent estimates of point prevalence and incidence using phylodynamics also showed extensive superspreading at this time, which likely contributed to the rapid expansion of the epidemic. Discordant inferences based on genomic and epidemiological data underscore the need for research to improve near real-time epidemic growth estimates by combining multiple disparate data sources to better inform outbreak response policy.

Potential health and economic impact associated with achieving risk factor control in Chinese adults with diabetes: a microsimulation modelling study

Background

The prevalence of diabetes has risen sharply in China. Improving modifiable risk factors such as glycaemia and blood pressure could substantially reduce disease burden and treatment costs to achieve a healthier China by 2030.

Methods

We used a nationally representative population-based survey of adults with diabetes in 31 provinces in mainland China to assess the prevalence of risk factor control. We adopted a microsimulation approach to estimate the impact of improved control of blood pressure and glycaemia on mortality, quality-adjusted life-years (QALYs), and healthcare cost. We applied the validated CHIME diabetes outcomes model over a 10-year time horizon. Baseline scenario of status quo was evaluated against alternative strategies based on World Health Organization and Chinese Diabetes Society guidelines.

Findings

Among 24,319 survey participants with diabetes (age 30-70), 69.1% (95% CI: 67.7-70.5) achieved optimal diabetes control (HbA1c <7% [53 mmol/mol]), 27.7% [26.1-29.3] achieved blood pressure control (<130/80 mmHg) and 20.1% (18.6-21.6) achieved both targets. Achieving 70% control rate for people with diabetes could reduce deaths before age 70 by 7.1% (5.7-8.7), reduce medical costs by 14.9% (12.3-18.0), and gain 50.4 QALYs (44.8-56.0) per 1000 people over 10 years compared to the baseline status quo. The largest health gains were for strategies including strict blood pressure control of 130/80 mmHg, particularly in rural areas.

Interpretation

Based on a nationally representative survey, few adults with diabetes in China achieved optimal control of glycaemia and blood pressure. Substantial health gains and economic savings are potentially achievable with better risk factor control especially in rural settings.

Funding

Chinese Central Government, Research Grants Council of the Hong Kong Special Administrative Region, China [27112518].

Estimating the transmission dynamics of SARS-CoV-2 Omicron BF.7 in Beijing after adjustment of the zero-COVID policy in November-December 2022

We tracked the effective reproduction number (R_t) of the predominant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant Omicron BF.7 in Beijing in November-December 2022 by fitting a transmission dynamic model parameterized with real-time mobility data to (i) the daily number of new symptomatic cases on 1-11 November (when China's zero-COVID interventions were still strictly enforced) and (ii) the proportion of individuals who participated in online polls on 10-22 December and self-reported to have been test-positive since 1 November. After China's announcement of 20 measures to transition from zero-COVID, we estimated that R_t increased to 3.44 (95% credible interval (CrI): 2.82-4.14) on 18 November and the infection incidence peaked on 11 December. We estimated that the cumulative infection attack rate (IAR; that is, proportion of the population infected since 1 November) in Beijing was 75.7% (95% CrI: 60.7-84.4) on 22 December 2022 and 92.3% (95% CrI: 91.4-93.1) on 31 January 2023. Surveillance programs should be rapidly set up to monitor the evolving epidemiology and evolution of SARS-CoV-2 across China.

Diminishing benefits of urban living for children and adolescents' growth and development

Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1-6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5-19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was <1.1 kg m-2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified.

Impact of host genetic polymorphisms on response to inactivated influenza vaccine in children

In randomized controlled trials of influenza vaccination, 550 children received trivalent-inactivated influenza vaccine, permitting us to explore relationship between vaccine response and host single nucleotide polymorphisms (SNPs) in 23 candidate genes with adjustment of multiple testing. For host SNPs in TLR7-1817G/T (rs5741880), genotype GT was associated with lower odds (OR: 0.22, 95% CI: 0.09, 0.53) of have post-vaccination hemagglutination-inhibiting (HAI) titers ≥40, compared with genotype GG and TT combined under the over-dominant model. For host SNPs in TLR8-129G/C (rs3764879), genotype GT was associated with lower odds (OR: 0.47; 95% CI: 0.28, 0.80) of have post vaccination HAI titers ≥40 compared with genotype GG and AA combined under the over-dominant model. Our results could contribute to the development of better vaccines that may offer improved protection to all recipients.

Real-world COVID-19 vaccine effectiveness against the Omicron BA.2 variant in a SARS-CoV-2 infection-naive population

The SARS-CoV-2 Omicron variant has demonstrated enhanced transmissibility and escape of vaccine-derived immunity. Although first-generation vaccines remain effective against severe disease and death, robust evidence on vaccine effectiveness (VE) against all Omicron infections, irrespective of symptoms, remains sparse. We used a community-wide serosurvey with 5,310 subjects to estimate how vaccination histories modulated risk of infection in infection-naive Hong Kong during a large wave of Omicron BA.2 epidemic in January-July 2022. We estimated that Omicron infected 45% (41-48%) of the local population. Three and four doses of BNT162b2 or CoronaVac were effective against Omicron infection 7 days after vaccination (VE of 48% (95% credible interval 34-64%) and 69% (46-98%) for three and four doses of BNT162b2, respectively; VE of 30% (1-66%) and 56% (6-97%) for three and four doses of CoronaVac, respectively). At 100 days after immunization, VE waned to 26% (7-41%) and 35% (10-71%) for three and four doses of BNT162b2, and to 6% (0-29%) and 11% (0-54%) for three and four doses of CoronaVac. The rapid waning of VE against infection conferred by first-generation vaccines and an increasingly complex viral evolutionary landscape highlight the necessity for rapidly deploying updated vaccines followed by vigilant monitoring of VE.

Risk of within-hotel transmission of SARS-CoV-2 during on-arrival quarantine in Hong Kong: an epidemiological and phylogenomic investigation

Background

On-arrival quarantine has been one of the primary measures to prevent the introduction of SARS-CoV-2 into Hong Kong since the start of the pandemic. Most on-arrival quarantines have been done in hotels, with the duration of quarantine and testing frequency during quarantine modified over time along with other pandemic control measures. However, hotels are not designed with infection control in mind. We aimed to systematically study the potential risk of acquisition of SARS-CoV-2 infection among individuals undergoing hotel quarantine.

Methods

We examined data on each laboratory-confirmed COVID-19 case identified in on-arrival quarantine in a hotel in Hong Kong between 1 May 2020 and 31 January 2022. We sequenced the whole genomes of viruses from cases that overlapped with other confirmed cases in terms of the hotel of stay, date of arrival and date of testing positive. By combining multiple sources of evidence, we identify probable and plausible transmission events and calculate the overall risk of transmission.

Findings

Among 221 imported cases that overlapped with other cases detected during hotel quarantine with available sequence data, phylogenomic analyses identified five probable and two plausible clusters of within-hotel transmission. Only two of these clusters were recognised at the time. Including other clusters reported in Hong Kong, we estimate that 8-11 per 1000 cases identified in hotel quarantine may be infected by another unlinked case during quarantine, or 2-3 per 100,000 overseas arrivals.

Interpretation

We have identified additional undetected occurrences of COVID-19 transmission within hotel quarantine in Hong Kong. Although hotels provide suboptimal infection control as improvised quarantine facilities, the risk of contracting infection whilst in quarantine is low. However, these unlikely events could have high consequences by allowing the virus to spread into immunologically naïve communities. Additional vigilance should be taken in the absence of improved controls to identify such events. If on-arrival quarantine is expected to be used for a long time, quarantine facilities could be purpose-built to minimise the risk of transmission.

Funding

Health and Medical Research Fund, Hong Kong.

Effectiveness of BNT162b2 and CoronaVac COVID-19 vaccination against asymptomatic and symptomatic infection of SARS-CoV-2 omicron BA.2 in Hong Kong: a prospective cohort study

BACKGROUND

COVID-19 vaccines provide protection against symptomatic infection that might require medical attention and against severe outcomes; however, there is a paucity of evidence regarding the effectiveness of the BNT162b2 and CoronaVac vaccines and their booster regimens against asymptomatic or mild omicron infections in the community. We aimed to measure the effectiveness of BNT162b2 and CoronaVac vaccines against asymptomatic and symptomatic SARS-CoV-2 omicron infections, during a period of omicron BA.2 predominance in Hong Kong.

METHODS

In this prospective cohort study in a population that was generally infection-naive before the large omicron BA.2 wave between January and late May, 2022, we established a public health surveillance platform to monitor the evolving activity of SARS-CoV-2 infections in the community. We recruited a cohort of individuals aged 5 years and older between March 1 and March 7, 2022, from the general population. Individuals were enrolled from all 18 districts of Hong Kong, according to a predefined age-stratified quota, primarily by random digit dialing (generating suitable eight-digit local telephone numbers by randomly picking sets of the first four digits from a sampling frame, and randomly generating the last four digits), and supplemented by our existing cohorts (which included cohorts for studying influenza vaccination from school-based vaccination programmes and cohorts for SARS-CoV-2 seroprevalence from the community), to ensure representativeness of the population in Hong Kong. Participants did weekly rapid antigen testing with a self-collected pooled nasal and throat swab, regardless of symptom and exposure status, from March 1 to April 15, 2022. Individuals reporting a history of SARS-CoV-2 infection confirmed by laboratory PCR testing before enrolment were excluded from the vaccine effectiveness analysis to avoid potential bias due to infection-induced immunity. The primary outcomes of the study were the incidence of SARS-CoV-2 infection, including asymptomatic and symptomatic infections, and the vaccine effectiveness of BNT162b2 and CoronaVac vaccines. The effectiveness of one, two, and three doses of vaccination was estimated with a Cox proportional hazards regression model with time-dependent covariates, allowing for changes in vaccination status over time, after adjustment for demographic factors and pre-existing medical conditions.

FINDINGS

Of the 8636 individuals included in the analysis, 7233 (84%) received at least two doses of vaccine, 3993 (46%) received booster doses, and 903 (10%) reported SARS-CoV-2 infection. Among these infections 589 (65·2%) were symptomatic and 314 (34·8%) were asymptomatic at the time of testing. Statistically significant protection against asymptomatic and symptomatic SARS-CoV-2 omicron infection was found only for those who received a BNT162b2 or CoronaVac booster dose, with a vaccine effectiveness of 41·4% (23·2 to 55·2; p=0·0001) and 32·4% (9·0 to 49·8; p=0·0098), respectively. The vaccine effectiveness of BNT162b2 and CoronaVac boosters was further increased to 50·9% (95% CI 31·0-65·0; p<0·0001) and 41·6% (15·0-59·8; p=0·0049), respectively, for symptomatic omicron infections. A similar pattern of vaccine effectiveness (55·8%, 22·9-74·6; p=0·0040) was also conferred after receipt of a BNT162b2 booster by individuals who received a CoronaVac primary vaccination series.

INTERPRETATION

Two doses of either vaccine did not provide significant protection against COVID-19 infection. However, receipt of a BNT162b2 booster or CoronaVac booster was associated with a significantly lower risk of omicron BA.2 infection and symptomatic infection. Our findings confirm the effectiveness of booster doses to protect against mild and asymptomatic infection.

FUNDING

Henry Fok Foundation and Hong Kong Health Bureau.

Real-world effectiveness of early molnupiravir or nirmatrelvir-ritonavir in hospitalised patients with COVID-19 without supplemental oxygen requirement on admission during Hong Kong's omicron BA.2 wave: a retrospective cohort study

BACKGROUND

Data on the effectiveness of oral antivirals in patients with mild-to-moderate COVID-19 are urgently needed. This retrospective cohort study aimed to evaluate the clinical and virological outcomes associated with molnupiravir or nirmatrelvir-ritonavir use in hospitalised patients with mild-to-moderate COVID-19 during a pandemic wave dominated by the omicron BA.2 subvariant.

METHODS

We analysed data from a territory-wide retrospective cohort of patients in Hong Kong who were hospitalised with a confirmed diagnosis of SARS-CoV-2 infection between Feb 26 and April 26, 2022. Data were extracted from the Hospital Authority, the Department of Health, and the Hong Kong Death Registry. Patients were eligible for inclusion if their admission date was within 3 days before or after confirmation of their COVID-19 diagnosis. Those who were admitted to hospital more than 5 days after symptom onset, were younger than 18 years, had a history of oral antiviral use before admission, required supplemental oxygen on admission, had drug-related contraindications to nirmatrelvir-ritonavir use, or had severe renal or severe liver impairment were excluded. Patients who received the oral antivirals molnupiravir or nirmatrelvir-ritonavir were matched with controls using propensity-score matching in a ratio of 1:1. The primary outcome was all-cause mortality and secondary outcomes included a composite outcome of disease progression (all-cause mortality, initiation of invasive mechanical ventilation [IMV], intensive care unit [ICU] admission, or the need for oxygen therapy) and each of these individual disease progression outcomes, and time to reaching a low viral burden (RT-PCR cycle threshold value ≥30). For each event outcome, crude incidence rates were calculated and hazard ratios (HRs) estimated using Cox regression models.

FINDINGS

We identified 40 776 patients hospitalised with SARS-CoV-2 infection during the study period, with a mean follow-up of 41·3 days (total 925 713 person-days). After exclusions and propensity-score matching, we included 1856 molnupiravir recipients and 1856 matched controls, and 890 nirmatrelvir-ritonavir recipients and 890 matched controls. A lower risk of all-cause mortality was observed in molnupiravir recipients (crude incidence rate per 10 000 person-days 19·98 events [95% CI 16·91-23·45]) versus matched controls (38·07 events [33·85-42·67]; HR 0·48 [95% CI 0·40-0·59], p<0·0001) and in nirmatrelvir-ritonavir recipients (10·28 events [7·03-14·51]) versus matched controls (26·47 events [21·34-32·46]; HR 0·34 [0·23-0·50], p<0·0001). Oral antiviral recipients also had lower risks of the composite disease progression outcome (molnupiravir HR 0·60 [95% CI 0·52-0·69], p<0·0001; nirmatrelvir-ritonavir 0·57 [0·45-0·72], p<0·0001) and need for oxygen therapy (molnupiravir 0·69 [0·57-0·83], p=0·0001; nirmatrelvir-ritonavir 0·73 [0·54-0·97], p=0·032) compared with controls. Time to achieving a low viral burden was significantly shorter among oral antiviral recipients than matched controls (molnupiravir HR 1·38 [95% CI 1·15-1·64], p=0·0005; nirmatrelvir-ritonavir 1·38 [1·07-1·79], p=0·013). Significant differences in initiation of IMV and ICU admission were not found.

INTERPRETATION

During a wave of SARS-CoV-2 omicron BA.2, initiation of novel oral antiviral treatments in hospitalised patients not requiring oxygen therapy on admission showed substantial clinical benefit. Our findings support the early use of oral antivirals in this population of patients.

FUNDING

Health and Medical Research Fund (Health Bureau, Government of the Hong Kong Special Administrative Region).

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

Seroepidemiology of enterovirus A71 infection in prospective cohort studies of children in southern China, 2013-2018

Enterovirus A71 (EV-A71)-related hand, foot, and mouth disease (HFMD) imposes a substantial clinical burden in the Asia Pacific region. To inform policy on the introduction of the EV-A71 vaccine into the National Immunization Programme, we investigated the seroepidemiological characteristics of EV-A71 in two prospective cohorts of children in southern China conducted between 2013 and 2018. Our results show that maternal antibody titres declined rapidly in neonates, with over half becoming susceptible to EV-A71 at 1 month of age. Between 6 months and 2 years of age, over 80% of study participants were susceptible, while one third remained susceptible at 5 years old. The highest incidence of EV-A71 infections was observed in children aged 5-6 months. Our findings support EV-A71 vaccination before 6 months for birth cohorts in southern China, potentially with a one-time catch-up vaccination for children 6 months-5 years old. More regionally representative longitudinal seroepidemiological studies are needed to further validate these findings.

Real-world effectiveness of molnupiravir and nirmatrelvir plus ritonavir against mortality, hospitalisation, and in-hospital outcomes among community-dwelling, ambulatory patients with confirmed SARS-CoV-2 infection during the omicron wave in Hong Kong: an observational study

BACKGROUND

Little is known about the real-world effectiveness of oral antivirals against the SARS-CoV-2 omicron (B.1.1.529) variant. We aimed to assess the clinical effectiveness of two oral antiviral drugs among community-dwelling COVID-19 outpatients in Hong Kong.

METHODS

In this observational study, we used data from the Hong Kong Hospital Authority to identify an unselected, territory-wide cohort of non-hospitalised patients with an officially registered diagnosis of SARS-CoV-2 infection between Feb 26 and June 26, 2022, during the period in which the omicron subvariant BA.2.2 was dominant in Hong Kong. We used a retrospective cohort design as primary analysis, and a case-control design as sensitivity analysis. We identified patients with COVID-19 who received either molnupiravir (800 mg twice daily for 5 days) or nirmatrelvir plus ritonavir (nirmatrelvir 300 mg and ritonavir 100 mg twice daily for 5 days, or nirmatrelvir 150 mg and ritonavir 100 mg if estimated glomerular filtration rate was 30-59 mL/min per 1·73 m2). Outpatient oral antiviral users were matched with controls using propensity score (1:10) according to age, sex, date of SARS-CoV-2 infection diagnosis, Charlson Comorbidity Index score, and vaccination status. Study outcomes were death, COVID-19-related hospitalisation, and in-hospital disease progression (in-hospital death, invasive mechanical ventilation, or intensive care unit admission). Hazard ratios (HRs) were estimated by Cox regression for the primary analysis, and odds ratios in oral antiviral users compared with non-users by logistic regression for the sensitivity analysis.

FINDINGS

Among 1 074 856 non-hospitalised patients with COVID-19, 5383 received molnupiravir and 6464 received nirmatrelvir plus ritonavir in the community setting. Patients were followed up for a median of 103 days in the molnupiravir group and 99 days in the nirmatrelvir plus ritonavir group. Compared with nirmatrelvir plus ritonavir users, those on molnupiravir were older (4758 [85·9%] vs 4418 [88.7%] aged >60 years) and less likely to have been fully vaccinated (1850 [33·4%] vs 800 [16·1%]). Molnupiravir use was associated with lower risks of death (HR 0·76 [95% CI 0·61-0·95]) and in-hospital disease progression (0·57 [0·43-0·76]) than non-use was, whereas risk of hospitalisation was similar in both groups (0·98 [0·89-1·06]). Nirmatrelvir plus ritonavir use was associated with lower risks of death (0·34 [0·22-0·52]), hospitalisation (0·76 [0·67-0·86]), and in-hospital disease progression (0·57 [0·38-0·87]) than non-use was. We consistently found reduced risks of mortality and hospitalisation associated with early oral antiviral use among older patients. The findings from the case-control analysis broadly supported those from the primary analysis.

INTERPRETATION

During Hong Kong's wave of SARS-CoV-2 omicron subvariant BA.2.2, among non-hospitalised patients with COVID-19, early initiation of novel oral antivirals was associated with reduced risks of mortality and in-hospital disease progression. Nirmatrelvir plus ritonavir use was additionally associated with a reduced risk of hospitalisation.

FUNDING

Health and Medical Research Fund, Health Bureau, Government of Hong Kong Special Administrative Region, China.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

Performance of saline and water gargling for SARS-CoV-2 reverse transcriptase PCR testing: a systematic review and meta-analysis

The performance of gargling for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcriptase (RT)-PCR testing has not been previously reviewed. This review systematically assessed the performance of saline and water gargling for SARS-CoV-2 RT-PCR testing in the settings of diagnosing and monitoring viral shedding.We included original studies comparing the performance of gargling and (oropharyngeal-)nasopharyngeal swabs for SARS-CoV-2 RT-PCR testing. Studies conducted in either suspected individuals or confirmed cases were included and analysed separately. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were examined using random-effects models.Gargles achieved a high overall sensitivity (91%), specificity (97%), PPV (95%) and NPV (91%) for SARS-CoV-2 RT-PCR testing. Studies using saline gargle and water gargle have an overall sensitivity of 97% and 86%, respectively. The sensitivity values were largely maintained for saline and water gargling on stratified analysis, for both diagnosis (96% and 92%) and viral shedding monitoring (98% and 78%). A higher sensitivity was also reported by studies using sterile saline (100%), a smaller amount of gargling solution (92% versus 87%) and a longer gargling duration (95% versus 86%).Our results supported the use of gargling as a sampling approach for SARS-CoV-2 RT-PCR testing, which achieved a high sensitivity for both diagnosis and viral shedding monitoring purposes. Further investigation on the comparative performance of different gargling mediums is needed to draw a definitive conclusion.

Association of growth patterns during infancy and puberty with lung function, wheezing and asthma in adolescents aged 17.5 years: evidence from ‘Children of 1997’ Hong Kong Chinese Birth Cohort

Background

Rapid growth is related to adverse respiratory outcomes although possibly confounded or limited by growth modelling methods. We investigated the association of infant and pubertal growth with lung function, wheezing and asthma in a non-Western setting.

Methods

In Hong Kong’s ‘Children of 1997’ Chinese birth cohort (n = 8327), weight during infancy and weight, height and body mass index (BMI) during puberty were modelled using a super-imposition by translation and rotation model to identify (larger or smaller) size, (earlier or later) tempo and (slower or faster) velocity. Sex-specific associations with forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), FEV1/FVC (Global Lung function Initiative z-score) and self-reported wheezing and asthma at ∼17.5 years were assessed.

Results

For each fraction higher than average weight growth velocity during infancy, FVC was higher in boys (0.90 SD, 95% CI 0.35; 1.44) and girls (0.77 SD, 95% CI 0.24; 1.30), FEV1/FVC was lower (–0.74 SD, 95% CI –1.38; –0.10) and wheezing was higher (odds ratio 6.92, 95% CI 1.60; 29.99) in boys and an inverse association with FVC was observed for tempo but not for size. Associations for weight growth velocity in puberty were similar but weaker. Greater size and higher velocity of BMI growth was associated with higher FVC, lower FEV1/FVC and higher asthma and wheezing risk.

Conclusion

Accelerated infant and pubertal weight growth were associated with disproportionate lung size and airway growth, and higher risk of asthma; optimizing early-life growth patterns could be important.

Regression-Based Strategies to Reduce Refractive Error-Associated Glaucoma Diagnostic Bias When Using OCT and OCT Angiography

Purpose

The purpose of this study was to correct refractive error-associated bias in optical coherence tomography (OCT) and OCT angiography (OCTA) glaucoma diagnostic parameters.

Methods

OCT and OCTA imaging were obtained from participants in the Hong Kong FAMILY cohort. The Avanti/AngioVue OCT/OCTA system was used to measure the peripapillary nerve fiber layer thickness (NFLT), peripapillary nerve fiber layer plexus capillary density (NFLP-CD), macular ganglion cell complex thickness (GCCT), and macular superficial vascular complex vascular density (SVC-VD). Healthy eyes, including ones with axial ametropia, were enrolled for analysis.

Results

A total of 1346 eyes from 792 participants were divided into 4 subgroups: high myopia (<−6D), low myopia (−6D to −1D), emmetropia (−1D to 1D), and hyperopia (>1D). After accounting for age, sex, and signal strength, multivariable regression showed strong dependence in most models for NFLT, GCCT, and NFLP-CD on axial eye length (AL), spherical equivalent (SE) refraction, and apparent optic disc diameter (DD). Optical analysis indicated that AL-related transverse optical magnification variations predominated over anatomic variations and were responsible for these trends. Compared to the emmetropic group, the false positive rates were significantly (Chi-square test P < 0.003) elevated in both myopia groups for NFLT, NFLP-CD, and GCCT. Regression-based adjustment of these diagnostic parameters with AL or SE significantly (McNemar test P < 0.03) reduced the elevated false positive rates.

Conclusions

Myopic eyes are biased to have lower NFLT, GCCT, and NFLP-CD measurements. AL- and SE-based adjustments were effective in mitigating this bias.

Translational Relevance

Adoption of these adjustments into commercial OCT systems may reduce false positive rates related to refractive error.

Slow Waning of Antibodies Following BNT162b2 as a Third Dose in Adults Who Had Previously Received 2 Doses of Inactivated Vaccine

We administered BNT162b2 as a third dose to 314 adults aged ≥30 years who had previously received 2 doses of inactivated vaccine. We collected blood samples before the third dose and again after 1 month and 6 months, and found robust antibody responses to the ancestral strain at 6 months after receipt of BNT162b2. Antibody responses to Omicron BA.2 by live virus neutralization were weaker after the third dose and had declined to a low level by 6 months.

Epidemiology of Infections with SARS-CoV-2 Omicron BA.2 Variant, Hong Kong, January-March 2022

Our analysis of data collected from multiple epidemics in Hong Kong indicated a shorter serial interval and generation time of infections with the SARS-CoV-2 Omicron variant. The age-specific case-fatality risk for Omicron BA.2.2 case-patients without complete primary vaccination was comparable to that of persons infected with ancestral strains in earlier waves.

The impact of road safety policies in a deregulated alcohol tax environment in Hong Kong: a 15-year time series analysis

BACKGROUND AND AIMS

Hong Kong reduced beer and wine tax in 2007, eliminated taxes on beer and wine and strengthened drink-driving legislation in 2008, and increased police traffic enforcement after the 2014 social unrest. This study aimed to measure the effects of implementing road safety policies on road traffic harm in the context of deregulated alcohol control policy in Hong Kong.

DESIGN

Population-based interrupted time series analysis using seasonal autoregressive integrated moving average (sARIMA) models. Multiple sensitivity analyses were conducted.

SETTING

Hong Kong, China and Singapore from January 2004 to December 2019.

CASES

A total of 313 728 road traffic injuries in Hong Kong and 163 773 road traffic injuries in Singapore as controls.

MEASUREMENTS

Monthly rates of road traffic injuries, non-fatal injuries and serious/fatal injuries from Hong Kong and Singapore Police Force.

FINDINGS

The elimination of alcohol taxes and the enactment of road safety legislation in 2008 were associated with immediate reductions in total road traffic injuries of 6.71% (95% CI, 1.99%-11.20%), serious/fatal injuries of 13.80% (95% CI, 1.85%-24.30%) and sustained declines in drink-driving and collisions involving drink-driving. The effects of the 2007 tax reduction were inconclusive. Progressively increasing traffic enforcement was associated with continuous reductions in road traffic injuries by 0.21% per month (95% CI, 0.13%-0.30%), and serious/fatal injuries by 1.10% per month (95% CI, 0.85%-1.35%). Effects at the corresponding timepoints in Singapore did not reach statistical significance; the results were inconclusive regarding confounding effects on both regions.

CONCLUSIONS

Despite weakened alcohol control and increased alcohol sales over the same period, road safety policies in Hong Kong are associated with net reductions in road traffic injuries, particularly serious/fatal injuries.

Strength and durability of antibody responses to BNT162b2 and CoronaVac

We studied 2780 adults in Hong Kong who received CoronaVac inactivated virus vaccine (Sinovac) and BNT162b2 mRNA vaccine ("Comirnaty", BioNTech/Fosun Pharma). We compared rates of antibody waning over time using an enzyme-linked immunosorbent assay for spike receptor binding domain and a surrogate virus neutralization test. We found stronger and more durable antibody responses to two doses of the mRNA vaccine, and slightly stronger initial antibody responses to each vaccine in younger adults and women. The weaker and less durable responses following CoronaVac support earlier provision of third doses to persons who previously received two doses of this vaccine.