Effectiveness of social distancing interventions in containing COVID-19 incidence: International evidence using Kalman filter

From node to network: weaving a global perspective on efficacy and costs of non-pharmaceutical interventions

Non-pharmaceutical intervention (NPI) policies, ranging from mild measures to total isolation, were implemented worldwide during the COVID-19 pandemic. We adopt a systematic approach to guide policymakers in deploying NPI policies to mitigate the pandemic's effects while balancing their social and economic impacts. Our results show that each NPI has an optimal duration, beyond which its effectiveness plateaus. Stricter policies require longer durations, and when sustained for the optimal period, earlier implementation is more effective. However, when this duration is unattainable, timing becomes critical, as both early and late implementation reduce efficacy. Stringent policies with insufficient durations may perform worse than less restrictive measures applied over the same period, and an NPI policy aimed at minimizing overall healthcare burden under a fixed policy duration may significantly intensify peak-time strains. Finally, as the virus becomes more transmissible and less lethal, the effectiveness gap between stringent and less restrictive policies narrows, with targeted interventions for vulnerable groups outperforming universal strict measures.

Serological survey in a university community after the fourth wave of COVID-19 in Senegal

A cross-sectional survey was conducted at Polytechnic High School (PHS) to assess the spread of COVID-19 infection among students and staff. A random cluster sampling was conducted between May 19 and August 18, 2022, after the fourth wave of COVID-19 in Senegal. IgM and IgG SARS-CoV-2 antibodies were screened using WANTAI SARS-CoV-2 ELISA assays. Seroprevalence and descriptive statistics were calculated, and associations between seropositivity and different factors were determined using logistic regression. A total of 637 participants were recruited and the median age was 21 years [18-63]. 62.0% of the participants were female, and 36.89% were male, with a male-to-female ratio = 0.59. The overall IgG and IgM seroprevalence were 92% and 6.91% respectively. Among those who tested positive for IgM, 6.75% were also positive for IgG, and 0.15% were negative for IgG. Interestingly, 6.90% of participants tested negative for both IgM and IgG. We found a higher IgM seroprevalence in men than women (9.4% vs. 5.6%) and a lower IgM seroprevalence in (18-25) age group compared to (55-65) years. We revealed a significant difference according to IgG seroprevalence among participants who declared fatigue symptoms [92.06% (95% CI: 89.96-94.16)] compared to those who did not [80.39% (95% CI: 77.31-83.47)], p = 0.0027. IgM seropositivity was found to be associated with Body Mass Index (BMI) categories (O.R. 0.238, p = 0.043), ethnic group (O.R. 0.723, p = 0.046), and marital status (O.R. 2.399, p = 0.021). Additionally, IgG seropositivity was linked to vaccination status (O.R. 4.741, p < 0.001). Our study found that most students and staff at PHS were exposed to SARS-CoV-2, confirming the virus's circulation at the time of the survey. We also identified differences in individual susceptibility that need further clarification. Our results highlight the importance of seroepidemiological surveys to assess the true impact of the COVID-19 pandemic in a community and to monitor variations in antibody response.

Easing anxiety symptoms through leisure activities during social isolation: Findings from nationally representative samples

Public health interventions implemented during the COVID-19 pandemic may exacerbate anxiety symptoms for many. We conducted this study to better understand the role of leisure activity in promoting mental wellness during times of social isolation and reduced access to recreation facilities and mental health support services. We analyzed nationally representative survey data collected by Statistics Canada as part of the Canadian Perspectives Survey Series (CPSS) during May 4-10 (CPSS 2) and July 20 to 26, 2020 (CPSS 4). Data related to leisure activity and anxiety symptoms as measured by a score of more than 10 on the General Anxiety Disorder scale were examined using descriptive and log-binomial regression analyses. Survey sampling weights were applied in all analyses, and regression results were adjusted for sociodemographic characteristics. Exercise and communication with friends and loved ones were the most frequently reported leisure activity. Prevalence of moderate to severe anxiety symptoms reported by participants was lower in CPSS 4 compared to CPSS 2. Results of adjusted log-binomial regression analyses revealed lower prevalence of moderate to severe anxiety symptoms in those who engaged in exercise and communication, while those who meditated exhibited higher prevalence. In conclusion, leisure activities, such as exercise and communication with loved ones, can promote mental wellness. Future research should clarify the role of meditation for mental wellness promotion during periods of social isolation.

Public Acceptance of Measures to Control Infectious Diseases Under Different Scenarios of Severity and Transmissibility

OBJECTIVES

Public health measures to control future epidemic threats of contagious disease, such as new variants of COVID-19, may be usefully informed by evidence about how acceptable they are likely to be, and the circumstances that condition this acceptance. This study considers how the acceptability of nonpharmaceutical interventions (NPIs) might depend on scenarios about the severity and transmissibility of the disease.

METHODS

A telephone survey was conducted among a representative cross-sectional sample of the Spanish adult population. Each respondent was randomly assigned to 1 of 4 possible hypothetical scenarios about the severity and transmissibility of the disease. Participants' responses about the acceptability of 11 NPI under this scenario were analyzed using multivariate regression and latent class cluster analysis.

RESULTS

A high risk of severe disease increases the acceptability of mask wearing, social distancing outdoors, lockdown, and isolation of infected cases, close contacts, and the vulnerable. A scenario in which the disease is highly transmissible would increase the acceptability of NPI that restrict movement and isolation. Most respondents would broadly accept most NPI in situations when either the severity or transmissibility was high.

CONCLUSIONS

This study showed that people are more willing to accept NPIs such as mask wearing, social distancing outdoors, lockdown, and isolation in severe disease scenarios. A highly transmissible disease scenario increases the acceptability of NPIs that isolate. A majority would broadly accept NPIs to counter public health emergencies, whereas 3% to 9% of the population would always be strongly against.

Association of Individual Behaviors With Infection Prevention Measures and COVID-19 Development: A Japanese Cross-Sectional Study

During the COVID-19 pandemic, people often modified their behaviors and performed individual infection control practices despite the uncertain effectiveness of these in preventing COVID-19. A cross-sectional study using a nationwide internet survey (Japan COVID-19 Society Internet Survey) was conducted from September 2022 through October 2022. The questionnaire consisted of individual-level social distancing behaviors and infection prevention measures, and COVID-19 vaccination status. A multivariate logistic regression was performed to determine factors associated with the diagnosis of COVID-19 in the last two months of the survey date. In total, 19,296 respondents were selected for the primary analysis. Of 19,296 respondents, those with COVID-19 diagnosed in the last two months were 1,909 (9.9%). Factors independently associated with a recent history of COVID-19 were meeting colleagues in person ≧ 1 per week (adjusted odds ratio [aOR] 1.72). The response of "never or rarely" to the question of taking out (i.e., dining in) foods was marginally associated with a recent history of COVID-19 (aOR 1.27). Most individual, infection prevention practices and behavioral modifications during the omicron variant phase of the pandemic did not substantially impact COVID-19 prevention in the community.

Glycyrrhiza glabra L. Extracts and Other Therapeutics against SARS-CoV-2 in Central Eurasia: Available but Overlooked

In Central Eurasia, the availability of drugs that are inhibitors of the SARS-CoV-2 virus and have proven clinical efficacy is still limited. The aim of this study was to evaluate the activity of drugs that were available in Kazakhstan during the acute phase of the epidemic against SARS-CoV-2. Antiviral activity is reported for Favipiravir, Tilorone, and Cridanimod, which are registered drugs used for the treatment of respiratory viral infections in Kazakhstan. A licorice (Glycyrrhiza glabra) extract was also incorporated into this study because it offered an opportunity to develop plant-derived antivirals. The Favipiravir drug, which had been advertised in local markets as an anti-COVID cure, showed no activity against SARS-CoV-2 in cell cultures. On the contrary, Cridanimod showed impressive high activity (median inhibitory concentration 66 μg/mL) against SARS-CoV-2, justifying further studies of Cridanimod in clinical trials. Tilorone, despite being in the same pharmacological group as Cridanimod, stimulated SARS-CoV-2 replication in cultures. The licorice extract inhibited SARS-CoV-2 replication in cultures, with a high median effective concentration of 16.86 mg/mL. Conclusions: The synthetic, low-molecular-weight compound Cridanimod suppresses SARS-CoV-2 replication at notably low concentrations, and this drug is not toxic to cells at therapeutic concentrations. In contrast to its role as an inducer of interferons, Cridanimod is active in cells that have a genetic defect in interferon production, suggesting a different mechanism of action. Cridanimod is an attractive drug for inclusion in clinical trials against SARS-CoV-2 and, presumably, other coronaviruses. The extract from licorice shows low activity against SARS-CoV-2. At the same time, high doses of 2 g/kg of this plant extract show little or no acute toxicity in animal studies; for this reason, licorice products can still be considered for further development as a safe, orally administered adjunctive therapy.

Do more stringent policies reduce daily COVID-19 case counts? Evidence from Canadian provinces

The enactment of COVID-19 policies in Canada falls under provincial jurisdiction. This study exploits time-series variation across four Canadian provinces to evaluate the effects of stricter COVID-19 policies on daily case counts. Employing data from this time-period allows an evaluation of the efficacy of policies independent of vaccine impacts. While both OLS and IV results offer evidence that more stringent Non-Pharmaceutical Interventions (NPIs) can reduce daily case counts within a short time-period, IV estimates are larger in magnitude. Hence, studies that fail to control for simultaneity bias might produce confounded estimates of the efficacy of NPIs. However, IV estimates should be treated as correlations given the possibility of other unobserved determinants of COVID-19 spread and mismeasurement of daily cases. With respect to specific policies, mandatory mask usage in indoor spaces and restrictions on business operations are significantly associated with lower daily cases. We also test the efficacy of different forecasting models. Our results suggest that Gradient Boosted Regression Trees (GBRT) and Seasonal Autoregressive-Integrated Moving Average (SARIMA) models produce more accurate short-run forecasts relative to Vector Auto Regressive (VAR), and Susceptible-Infected-Removed (SIR) epidemiology models. Forecasts from SIR models are also inferior to results from basic OLS regressions. However, predictions from models that are unable to correct for endogeneity bias should be treated with caution.

The illusion of personal health decisions for infectious disease management: disease spread in social contact networks

Close contacts between individuals provide opportunities for the transmission of diseases, including COVID-19. While individuals take part in many different types of interactions, including those with classmates, co-workers and household members, it is the conglomeration of all of these interactions that produces the complex social contact network interconnecting individuals across the population. Thus, while an individual might decide their own risk tolerance in response to a threat of infection, the consequences of such decisions are rarely so confined, propagating far beyond any one person. We assess the effect of different population-level risk-tolerance regimes, population structure in the form of age and household-size distributions, and different interaction types on epidemic spread in plausible human contact networks to gain insight into how contact network structure affects pathogen spread through a population. In particular, we find that behavioural changes by vulnerable individuals in isolation are insufficient to reduce those individuals' infection risk and that population structure can have varied and counteracting effects on epidemic outcomes. The relative impact of each interaction type was contingent on assumptions underlying contact network construction, stressing the importance of empirical validation. Taken together, these results promote a nuanced understanding of disease spread on contact networks, with implications for public health strategies.

Impact of pre-pandemic travel mobility patterns on the spatial diffusion of COVID-19 in South Korea

Introduction

Physical mobility is critical for the spread of infectious diseases in humans. However, few studies have conducted empirical investigations on the impact of pre-pandemic travel mobility patterns on the diffusion of coronavirus disease 2019 (COVID-19). Therefore, this study examines its impact at the city-county level on the diffusion by the wave period during the two-year pandemic in South Korea.

Methods

This study first employs factor analysis by using the travel origin-destination data by travel mode at the county level as of 2019 to derive pre-pandemic travel mobility patterns. Next, the study identifies how they had affected the diffusion of COVID-19 over time by employing the negative binomial regression models on confirmed COVID-19 cases for each wave, including the entire pandemic period.

Results

The study derived five pre-pandemic mobility patterns: 1) rail-oriented mobility, 2) intra-county bus-oriented mobility, 3) road-oriented mobility, 4) high-speed rail-oriented mobility, and 5) inter-county bus-oriented mobility. Among them, the biggest risk to the diffusion of COVID-19 was the rail-oriented mobility before the pandemic if controlling such measures as accessibility, physical environment, and demographic and socioeconomic indicators. In addition, the order of the magnitudes for the impact of pre-pandemic travel mobility factors on its spatial diffusion had not changed during experiencing the three different wave periods during the two-year pandemic in South Korea.

Conclusions

The study concludes that the rail-oriented travel mobility pattern before the pandemic could pose the greatest threat factor to the spatial spread of COVID-19 at any scale and time. Policymakers should develop strategies to prevent the spatial spread of COVID-19 by reducing human mobility for daily living in areas with strong rail mobility patterns formed before the pandemic.