SARS-CoV-2 prevalence associated to low socioeconomic status and overcrowding in an LMIC megacity: A population-based seroepidemiological survey in Lima, Peru

Evidence of rapid rise in population immunity from SARS-CoV-2 subclinical infections through pre-vaccination serial serosurveys in Pakistan

Background

Understanding factors associated with protective immunity against emerging viral infections is crucial for global health. Pakistan reported its first COVID-19 case on 26 February 2020, but experienced relatively low COVID-19-related morbidity and mortality between 2020 and 2022. The underlying reasons for this remain unclear, and our research aims to shed light on this crucial issue.

Methods

We conducted a serial population-based serosurvey over 16 months (rounds 1-4, July 2020 to November 2021) across households in urban (Karachi) and rural (Matiari) Sindh, sampling 1100 households and 3900 individuals. We measured antibodies in sera and tested a subset of respiratory samples for COVID-19 using polymerase chain reaction (PCR) and antigen tests, also measuring haemoglobin (Hb), C-reactive protein (CRP), vitamin D, and zinc in round 1.

Results

Participants showed 23% (95% confidence interval (CI) = 21.9-24.5) antibody seroprevalence in round 1, increasing across rounds 2-4 to 29% (95% CI = 27.4-30.6), 49% (95% CI = 47.2-50.9), and 79% (95% CI = 77.4-80.8), respectively. Urban residents had 2.6 times (95% CI = 1.9-3.6) higher odds of seropositivity than rural residents. Seropositivity did not differ between genders. Individuals aged 20-49 years had 7.5 (95% CI = 4.6-12.4) times higher odds of seropositivity compared to children aged 0-4 years. Most participants had no symptoms associated with COVID-19, with no reported mortality. Vitamin D deficiency was linked to seroprevalence. COVID-19 was confirmed in 1.8% of individuals tested via RT-PCR and antigen tests.

Conclusions

The data suggests a steady increase in humoral immunity in Pakistan, likely due to increased transmission and associated asymptomatic disease. Overall, this reflects the longitudinal trend of protection against severe acute respiratory syndrome coronavirus 2, leading to the relatively low morbidity and mortality observed in the population.

SARS-CoV-2 Infection and the Risk of New Chronic Conditions: Insights from a Longitudinal Population-Based Study

BACKGROUND

The post-acute impact of SARS-CoV-2 infections on chronic conditions remains poorly understood, particularly in general populations.

OBJECTIVES

Our primary aim was to assess the association between SARS-CoV-2 infections and new diagnoses of chronic conditions. Our two secondary aims were to explore geographic variations in this association and to assess the association between SARS-CoV-2 infections and the exacerbation of pre-existing conditions.

METHODS

This longitudinal study used data from 8086 participants of the Specchio-COVID-19 cohort in the canton of Geneva, Switzerland (2021-2023). Mixed-effects logistic regressions and geographically weighted regressions adjusted for sociodemographic, socioeconomic, and healthcare access covariates were used to analyze self-reported SARS-CoV-2 infections, new diagnoses of chronic conditions, and the exacerbation of pre-existing ones.

RESULTS

Participants reporting a SARS-CoV-2 infection were more likely to be diagnosed with a new chronic condition compared to those who did not report an infection (adjusted odds ratio [aOR] = 2.15, 95% CI 1.43-3.23, adjusted p-value = 0.002). Notable geographic variations were identified in the association between SARS-CoV-2 infections and new diagnoses. While a positive association was initially observed between SARS-CoV-2 infections and exacerbation of pre-existing chronic conditions, this association did not remain significant after adjusting p-values for multiple comparisons.

CONCLUSIONS

These findings contribute to understanding COVID-19's post-acute impact on chronic conditions, highlighting the need for targeted health management approaches and calling for tailored public health strategies to address the pandemic's long-term effects.

From risk factors to disease situations: A socio-spatial analysis of COVID-19 experiences in Lima, Peru

The goal of this qualitative research study, part of an interdisciplinary project, was to understand the overlapping geographical distribution of COVID-19 and tuberculosis burden in Lima. Using an ethnographic approach, we applied the concept of disease situations to explore how inhabitants' social and spatial situatedness affected their capacity to respond to the pandemic. Our results show that for some populations in Lima, the risk to develop COVID-19 did not emerge suddenly; it could be traced back to situations of living under subsistence models, relying on unstable sources of income, facing food insecurity, depending on certain mechanisms of social protection, residing in precarious living environments and lacking access to quality health care. These populations did not only have less resources to adjust to changes in daily life induced by the pandemic; they were also forced to constantly weigh the risk of COVID-19 against other pressing needs and potentially face increased risks when control measures were actually followed. Pre-existing social networks played fundamental roles as sources of emotional and material support. The lens of disease situations can help to identify and explain spatial and social configurations that enhance vulnerability, as well as resilience mechanisms that are in place to deal with crises. This perspective could inform the design of contextualised prevention and response strategies around health risks in cities as diverse as Lima, whilst building on existing resources at local levels.

Social epidemiology of urban COVID-19 inequalities in Latin America and Canada

BACKGROUND

The COVID-19 pandemic has spread through pre-existing fault lines in societies, deepening structural barriers faced by precarious workers, low-income populations, and racialized communities in lower income sub-city units. Many studies have quantified the magnitude of inequalities in COVID-19 distribution within cities, but few have taken an international comparative approach to draw inferences on the ways urban epidemics are shaped by social determinants of health.

METHODS

Guided by critical epidemiology, this study quantifies sub-city unit-level COVID-19 inequalities across eight of the largest metropolitan areas of Latin America and Canada. Leveraging new open-data sources, we use concentration indices to quantify income- and vulnerability-related inequalities in incidence, test positivity, and deaths over the first 125 weeks of the pandemic between January 2020 and May 2022.

RESULTS

Our findings demonstrate that incidence, deaths, and test positivity are all less concentrated in low-income sub-city units than would be expected, with incidence ranging concentration in lower income neighbourhoods in Toronto (CI = -0.07) to concentration in higher income neighbourhoods in Mexico City (CI = 0.33). Drawing on relevant studies and evaluations of data reliability, we conclude that the best available public surveillance data for the largest cities in Latin America are likely not reliable measures of the true COVID-19 disease burden. We also identify recurring trends in the evolution of inequalities across most cities, concluding that higher income sub-city units were frequent early epicentres of COVID-19 transmission across the Latin America and Canada.

CONCLUSIONS

Just as critical epidemiology points to individuals biologically embodying the material and social conditions in which we live, it may be just as useful to think of cities reifying their material and social inequities in the form of sub-city unit-level infectious disease inequities. By shifting away from a typical vulnerability-based social determinants of health frame, policymakers could act to redress and reduce externalities stemming from sub-city unit-level income inequality through redistributive and equity-promoting policies to shift the centre of gravity of urban health inequalities before the next infectious disease epidemic occurs.

Urban density, household overcrowding and the spread of COVID-19 in Australian cities

The UN-Habitat World Cities Report 2020 highlighted that overcrowded housing, not urban density, is the major contributing factor to the spread of COVID-19. The relatively successful ability of densely populated cities such as Seoul, Singapore, Tokyo and New York City to manage virus spread supports this. We hypothesise that, given the complexity of the interaction between people and place, the relative contribution of density and crowding to the spread of infectious diseases may be contingent on local factors. To directly compare the role of urban density and household overcrowding, we examine each in relation to COVID-19 incidence in the three largest cities in Australia, Sydney, Melbourne and Brisbane, as the pandemic unfolded from July 2021 to January 2022. Using ecological models adjusted for spatial autocorrelation and area-level measures of age and socio-economic factors, we assess the association between population density, overcrowding in homes, and COVID-19 infections in local neighbourhoods. Challenging prevailing assumptions, we find evidence for an effect of both density and overcrowding on COVID-19 infections depending on the city and area within cities; that is, depending on the local context. For example, in the southwestern suburbs of Sydney, the case rate decreases by between 0.4 and 6.4 with every one-unit increase in gross density however the case rate increases by between 0.01 and 9.6 with every one-unit increase in total overcrowding. These findings have important implications for developing pandemic response strategies: public health measures that target either density (e.g., lockdowns and restricted range of travel) or overcrowding (e.g., restricting number of people relative to dwelling, mask-wearing indoors, vaccination prioritisation) must be cognisant of the geographically local contexts in which they are implemented.

Prevalence of SARS-CoV-2 Antibodies in Kosovo-Wide Population-Based Seroepidemiological Study

BACKGROUND

Seroprevalence studies have proven to be an important tool in tracking the progression of the coronavirus disease 2019 (COVID-19) pandemic. The aim of this study was to measure the seroprevalence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the general population of Kosovo by gender, age group and region and among asymptomatic people.

METHOD

The Institute of Public Health of Kosovo conducted a cross-sectional population-based survey, aligned with the protocols of the WHO Unity Studies, from the beginning of May to the end of June 2021.

RESULTS

The survey covered a total of 2204 people with a response rate of 91.8% (41.9% [923] males and 51.2% [1281] females). In May to June 2021, the prevalence of antibodies in the overall population (IgG antibodies ≥ 1.1) was 37.0%. Seroprevalence was 34.4% in men and 38.9% in women (p < 0.05), with the highest percentage (48.7%) found in the 60-69 years' age group. The overall prevalence of acute IgM antibodies (IgM ≥ 1.1) was 1% (95% CI: 0.7%-1.5%), with no significant difference between genders and the highest prevalence among participants of 60-69 years of age (1.6%; 95% CI: 0.7%-3.6%).

CONCLUSION

A high prevalence of antibodies against SARS-CoV-2 was found in Kosovo before the start of the vaccination campaign. However, the results of the survey suggested that, by the end of June 2021, a desirable level of protection from the SARS-CoV-2 virus had not been reached.

Differences in SARS-COV-2 seroprevalence in the population of Cusco, Peru

Background

The spread of the coronavirus disease 2019 (COVID-19) in Peru has been reported at the regional level, few studies have evaluated its spread at the provincial level, in which the mechanisms could be different.

Methods

We conducted an analytical, cross-sectional, multistage observational population study to assess the seroprevalence of SARS-COV-2 at the provincial and urban/rural levels in a high-altitude setting. The sampling unit was the household, including a randomly selected family member. Sampling was performed using a data collection sheet on clinical and epidemiological variables. Chemiluminescence tests were used to detect total anti-SARS-COV-2 antibodies (IgG and IgM simultaneously). The percentages were adjusted to the sampling design.

Results

The overall prevalence in the region of Cusco was 25.9%, with considerably different prevalence between the 13 provinces (from 15.9% in Acomayo to 40.1% in Canchis) and between rural (21.1%) and urban (31.7%) areas. In multivariable model, living in a rural area was a protective factor (adjusted prevalence ratio [aPR], 0.68; 95% confidence interval [CI], 0.61-0.76).

Conclusions

Geographic diversity and population density determine different prevalence rates, typically lower in rural areas, possibly due to natural social distancing or limited interaction with people at risk.

Differences in family functioning before and during the COVID-19 pandemic: an observational study in Peruvian families

The COVID-19 pandemic has had a major impact on family relationships, as several families have lost family members due to COVID-19 pandemic and become physically and emotionally estranged due to lockdown measures and critically economic periods. Our study contrasted two hypotheses: (1) family functioning changed notably before and after the COVID-19 pandemic initiation in terms of cohesion, flexibility, communication and satisfaction; (2) balanced families have a greater capacity to strictly comply with quarantine (i.e., social confinement), compared to unbalanced families. We performed an observational study comparing family functioning between two independent groups, evaluated before and during the first wave of the COVID-19 pandemic in Peru. A total of 7,980 participants were included in the study. For the first hypothesis, we found that, during the pandemic, families became more balanced in terms of cohesion (adjusted before-during mean difference or β1 = 1.4; 95% CI [1.0-1.7]) and flexibility (β2 = 2.0; 95% CI [1.6-2.4]), and families were less disengaged (β3 = -1.9; 95% CI [-2.3 to -1.5]) and chaotic (β4 = -2.9; 95% CI [-3.3 to -2.4]). Regarding the second hypothesis, we confirmed that families with balanced cohesion (adjusted prevalence ratio or aPR = 1.16; 95% CI [1.12-1.19) and flexibility (aPR = 1.23; 95% CI [1.18-1.27]) allowed greater compliance with quarantine restrictions; while disengaged (aPR = 0.91; 95% CI [0.88-0.93]) and chaotic families (aPR = 0.89; 95% CI [0.87-0.92]) were more likely to partially comply or not comply with the quarantine. Finally, family communication (aPR = 1.17; 95% CI [1.11-1.24]) and satisfaction (aPR = 1.18; 95% CI [1.11-1.25]) also played a role in favouring quarantine compliance. This new evidence enlightens the family systems theory while informing future interventions for improving compliance with quarantine measures in the context of social confinement.

Regional clustering and waves patterns due to COVID-19 by the index virus and the lambda/gamma, and delta/omicron SARS-CoV-2 variants in Peru

Background

Coronavirus disease 2019 (COVID-19) impact varies substantially due to various factors, so it is critical to characterize its main differences to inform decision-makers about where to focus their interventions and differentiate mitigation strategies. Up to this date, little is known about the patterns and regional clustering of COVID-19 waves worldwide.

Methods

We assessed the patterns and regional clustering of COVID-19 waves in Peru by using the weekly mortality rates for each of the 25 regions as an outcome of interest. We obtained the death counts from the National Informatics System of Deaths and population estimates from the National Registry of Identification and Civil Status. In addition, we characterized each wave according to its duration, peak, and mortality rates by age group and gender. Additionally, we used polynomial regression models to compare them graphically and performed a cluster analysis to identify regional patterns.

Results

We estimated the average mortality rate at the first, second, and third waves at 13.01, 14.12, and 9.82 per 100,000 inhabitants, respectively, with higher mortality rates among elders and men. The patterns of each wave varied substantially in terms of duration, peak, impact, and wave shapes. Based on our clustering analysis, during the first wave caused by the index virus, the 25 regions of Peru presented six different wave patterns. However, the regions were clustered in two different wave patterns during the second and third, caused by alpha/lambda/delta and omicron.

Conclusions

The propagation of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) variants behaved in Peru with varying wave patterns and regional clustering. During the COVID-19 pandemic, the weekly mortality rates followed different spatiotemporal patterns with solid clustering, which might help project the impact of future waves of COVID-19.

SARS-CoV-2 seroprevalence on the north coast of Peru: A cross-sectional study after the first wave

BACKGROUND

Peru had the second-highest number of COVID-19 cases in Latin America. After the first wave, Peru registered more than 900,000 cases of COVID-19 and more than 36,000 confirmed deaths from the disease. Tumbes, a border area with poor sanitation and not enough water, had the fifth highest death rate. The cross-sectional analytic study aimed: a) to assess seroprevalence of COVID-19 after the first wave; b) to assess sociodemographic determinants and symptoms associated with a positive COVID-19 antibody lateral flow test.

METHODOLOGY/PRINCIPAL FINDINGS

We performed this study between November 11th and November 30th, 2020, in an informal settlement in Tumbes. Individuals older than two years were invited to participate in a systematic random sample from one in every four households. Finger-prick blood samples were collected, and a census and symptom survey were applied. Within the chosen house, one adult over 18 years of age was chosen for a PCR-RT molecular test. Overall seroprevalence was 25.59%, adjusted seroprevalence was 24.82% (95%CI 22.49-27.25). Women had higher adjusted seroprevalence (28.03% vs 21.11%; 95% CI 24.83-31.41, p = 0.002). Symptoms as fever (PR 1.89: 95% CI 1.44-2.48, p<0.001), general discomfort (PR 1.67; 95% CI 1.23-2.26, p = 0.001), cough (PR 2.0; 95% CI 1.60-2.50, p<0.001), nasal congestion (PR 1.46; 95% CI 1.03-2.09, p = 0.036), respiratory distress (PR 1.64; 95% CI 1.04-2.56, p = 0.031), headache (PR 1.54; 95% CI 1.09-2.17, p = 0.014), anosmia (PR 1.78; 95% CI 1.01-3.14, p = 0.046) and ageusia (PR 2.31; 95% CI 1.48-3.61, p<0.001) were associated with a positive covid-19 antibody lateral flow test.

CONCLUSIONS/SIGNIFICANCE

The COVID-19 transmission and distribution were highlighted by this cross-sectional study. The data will help the Ministry of Health improve its monitoring, surveillance, and monitoring of respiratory community sequelae in the future.

Dynamics of SARS-CoV-2 seroassay sensitivity: a systematic review and modelling study

BackgroundSerological surveys have been the gold standard to estimate numbers of SARS-CoV-2 infections, the dynamics of the epidemic, and disease severity. Serological assays have decaying sensitivity with time that can bias their results, but there is a lack of guidelines to account for this phenomenon for SARS-CoV-2.AimOur goal was to assess the sensitivity decay of seroassays for detecting SARS-CoV-2 infections, the dependence of this decay on assay characteristics, and to provide a simple method to correct for this phenomenon.MethodsWe performed a systematic review and meta-analysis of SARS-CoV-2 serology studies. We included studies testing previously diagnosed, unvaccinated individuals, and excluded studies of cohorts highly unrepresentative of the general population (e.g. hospitalised patients).ResultsOf the 488 screened studies, 76 studies reporting on 50 different seroassays were included in the analysis. Sensitivity decay depended strongly on the antigen and the analytic technique used by the assay, with average sensitivities ranging between 26% and 98% at 6 months after infection, depending on assay characteristics. We found that a third of the included assays departed considerably from manufacturer specifications after 6 months.ConclusionsSeroassay sensitivity decay depends on assay characteristics, and for some types of assays, it can make manufacturer specifications highly unreliable. We provide a tool to correct for this phenomenon and to assess the risk of decay for a given assay. Our analysis can guide the design and interpretation of serosurveys for SARS-CoV-2 and other pathogens and quantify systematic biases in the existing serology literature.

COVID-19 Pandemic Response Preparedness and Risk Perceptions Among Peruvian Veterinarians and Animal Care Workers

Peruvian veterinarians and animal care workers (VACW) are primary responders in the event of disasters or emergencies, yet they face unique concerns that could impede or block their essential functions in public health preparedness in comparison with VACWs in other countries. In this study, we used the Ready, Willing, and Able model via electronic survey to evaluate the perception of risks and barriers that Peruvian VACWs faced when deciding whether to continue working during the COVID-19 pandemic between July and December 2020. We used logistic regression models to evaluate associations between demographic characteristics, perceived role, and contact scores with 8 outcomes: knowledge of COVID-19; confidence in safety protocols; perceived threat; perceived job efficacy; perceived barriers; and readiness, willingness, and ability to respond to the COVID-19 pandemic. Less than 50% of respondents reported barriers to report to work during the pandemic. Respondents who reported higher contact with coworkers had an increased confidence in safety protocols (OR 5.16; 95% CI, 1.36 to 19.61) and willingness (OR 3.76; 95% CI, 1.14 to 12.47) to respond to the pandemic. Close contacts with essential workers and higher economic income were associated with higher reported knowledge of COVID-19. Respondents with higher perceived job efficacy had higher odds of reporting being ready, willing, and able to respond to COVID-19, while those who identified more barriers to report to work had lower odds of being ready, willing, and able to respond. The findings from this study, which showed differences from VACWs in the United States, can be used by individuals designing programs to improve pandemic and disaster preparedness in this essential, yet understudied and vulnerable, workforce.

COVID-19 in Latin America and the Caribbean: Two years of the pandemic

Worldwide, nations have struggled during the coronavirus disease 2019 (COVID-19) pandemic. However, Latin America and the Caribbean faced an unmatched catastrophic toll. As of March 2022, the region has reported approximately 15% of cases and 28% of deaths worldwide. Considering the relatively late arrival of SARS-CoV-2, several factors in the region were determinants of the humanitarian crisis that ensued. Pandemic unpreparedness, fragile healthcare systems, forthright inequalities, and poor governmental support facilitated the spread of the virus throughout the region. Moreover, reliance on repurposed and ineffective drugs such as hydroxychloroquine and ivermectin-to treat or prevent COVID-19-was publicised through misinformation and created a false sense of security and poor adherence to social distancing measures. While there were hopes that herd immunity could be achieved after the region's disastrous first peak, the emergence of the Gamma, Lambda, and Mu variants made this unattainable. This review explores how Latin America and the Caribbean fared during the first 2 years of the pandemic, and how, despite all the challenges, the region became a global leader in COVID-19 vaccination, with 63% of its population fully vaccinated.

SARS-CoV-2 infections in infants in Haiti 2020–2021; evidence from a seroepidemiological cohort

Few data are available on frequency of SARS-CoV-2 infection among very young children in low- to middle-income countries (LMIC), with the studies that are available biased towards higher income countries with low reported infection and seroconversion rates. Between February 2019 and March 2021, 388 dried blood spot (DBS) samples were obtained from 257 children less than 30 months of age as part of a prospective observational cohort study of pregnant women and their infants in Haiti; longitudinal samples were available for 107 children. In a subsequent retrospective analysis, DBS samples were tested by ELISA for antibody targeting the receptor binding domain of the SARS-CoV-2 S1 protein. Over the course of the study, 16·7% of the infants became seropositive. All seropositive samples were collected after March 19, 2020 (the date of the first reported COVID-19 case in Haiti) with the highest hazards measured in August 2020. Sampling date was the only covariate associated with the hazard of seroconversion. Our data provide an estimate of SARS-CoV-2 infection rates among very young children without prior SARS-CoV-2 exposure during the initial pandemic waves in Haiti, and demonstrate that these children mount a detectable serological response which is independent of patient age.

Performance of SARS-CoV-2 Antigens in a Multiplex Bead Assay for Integrated Serological Surveillance of Neglected Tropical and Other Diseases

Serosurveillance can provide estimates of population-level exposure to infectious pathogens and has been used extensively during the COVID-19 pandemic. Simultaneous, serological testing for multiple pathogens can be done using bead-based immunoassays to add value to disease-specific serosurveys. We conducted a validation of four SARS-CoV-2 antigens-full-length spike protein, two receptor binding domain proteins, and the nucleocapsid protein-on our existing multiplex bead assay (MBA) for enteric diseases, malaria, and vaccine preventable diseases. After determining the optimal conditions for coupling the antigens to microsphere beads, the sensitivity and specificity of the assay were determined on two instruments (Luminex-200 and MAGPIX) when testing singly (monoplex) versus combined (multiplex). Sensitivity was assessed using plasma from 87 real-time reverse transcription polymerase chain reaction (rRT-PCR) positive persons collected in March-May of 2020 and ranged from 94.3% to 96.6% for the different testing conditions. Specificity was assessed using 98 plasma specimens collected prior to December 2019 and plasma from 19 rRT-PCR negative persons and ranged from 97.4% to 100%. The positive percent agreement was 93.8% to 97.9% using 48 specimens collected > 21 days post-symptom onset, while the negative percent agreement was ≥ 99% for all antigens. Test performance was similar using monoplex or multiplex testing. Integrating SARS-CoV-2 serology with other diseases of public health interest could add significant value to public health programs that have suffered severe programmatic setbacks during the COVID-19 pandemic.

Sero-prevalence and risk factors for Severe Acute Respiratory Syndrome Coronavirus 2 infection in women and children in a rural district of Bangladesh: A cohort study

Background

Bangladesh reported its first COVID-19 case on March 8, 2020. Despite lockdowns and promoting behavioural interventions, as of December 31, 2021, Bangladesh reported 1.5 million confirmed cases and 27 904 COVID-19-related deaths. To understand the course of the pandemic and identify risk factors for SARs-Cov-2 infection, we conducted a cohort study from November 2020 to December 2021 in rural Bangladesh.

Methods

After obtaining informed consent and collecting baseline data on COVID-19 knowledge, comorbidities, socioeconomic status, and lifestyle, we collected data on COVID-like illness and care-seeking weekly for 54 weeks for women (n = 2683) and their children (n = 2433). Between March and July 2021, we tested all participants for SARS-CoV-2 antibodies using ROCHE's Elecsys® test kit. We calculated seropositivity rates and 95% confidence intervals (95% CI) separately for women and children. In addition, we calculated unadjusted and adjusted relative risk (RR) and 95% CI of seropositivity for different age and risk groups using log-binomial regression models.

Results

Overall, about one-third of women (35.8%, 95% CI = 33.7-37.9) and one-fifth of children (21.3%, 95% CI = 19.2-23.6) were seropositive for SARS-CoV-2 antibodies. The seroprevalence rate doubled for women and tripled for children between March 2021 and July 2021. Compared to women and children with the highest household wealth (HHW) tertile, both women and children from poorer households had a lower risk of infection (RR, 95% CI for lowest HHW tertile women (0.83 (0.71-0.97)) and children (0.75 (0.57-0.98)). Most infections were asymptomatic or mild. In addition, the risk of infection among women was higher if she reported chewing tobacco (RR = 1.19,95% CI = 1.03-1.38) and if her husband had an occupation requiring him to work indoors (RR = 1.16,  95% CI = 1.02-1.32). The risk of infection was higher among children if paternal education was >5 years (RR = 1.37, 95% CI = 1.10-1.71) than in children with a paternal education of ≤5 years.

Conclusions

We provided prospectively collected population-based data, which could contribute to designing feasible strategies against COVID-19 tailored to high-risk groups. The most feasible strategy may be promoting preventive care practices; however, collecting data on reported practices is inadequate. More in-depth understanding of the factors related to adoption and adherence to the practices is essential.

Regional clustering and waves patterns due to COVID-19 by the index virus and the lambda/gamma, and delta/omicron SARS-CoV-2 variants in Peru

Background: Coronavirus disease 2019 (COVID-19) impact varies substantially due to various factors, so it is critical to characterize its main differences to inform decision-makers about where to focus their interventions and differentiate mitigation strategies. Up to this date, little is known about the patterns and regional clustering of COVID-19 waves worldwide.  Methods: We assessed the patterns and regional clustering of COVID-19 waves in Peru by using the weekly mortality rates for each of the 25 regions as an outcome of interest. We obtained the death counts from the National Informatics System of Deaths and population estimates from the National Registry of Identification and Civil Status. In addition, we characterized each wave according to its duration, peak, and mortality rates by age group and gender. Additionally, we used polynomial regression models to compare them graphically and performed a cluster analysis to identify regional patterns.  Results: We estimated the average mortality rate at the first, second, and third wave at 13.01, 14.12, and 9.82 per 100,000 inhabitants, respectively, with higher mortality rates among elders and men. The patterns of each wave varied substantially in terms of duration, peak, impact, and wave shapes. Based on our clustering analysis, during the first wave caused by the index virus, the 25 regions of Peru presented six different wave patterns. However, the regions were clustered in two different wave patterns during the second and third, caused by alpha/lambda/delta and omicron.  Conclusions: The propagation of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) variants behaved in Peru with varying wave patterns and regional clustering. During the COVID-19 pandemic, the weekly mortality rates followed different spatiotemporal patterns with solid clustering, which might help project the impact of future waves of COVID-19.

Seroprevalence of SARS-CoV-2 infection and associated factors among Bangladeshi slum and non-slum dwellers in pre-COVID-19 vaccination era: October 2020 to February 2021

BACKGROUND

Seroprevalence studies have been carried out in many developed and developing countries to evaluate ongoing and past infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Data on this infection in marginalized populations in urban slums are limited, which may offer crucial information to update prevention and mitigation policies and strategies. We aimed to determine the seroprevalence of SARS-CoV-2 infection and factors associated with seropositivity in slum and non-slum communities in two large cities in Bangladesh.

METHODS

A cross-sectional study was carried out among the target population in Dhaka and Chattogram cities between October 2020 and February 2021. Questionnaire-based data, anthropometric and blood pressure measurements and blood were obtained. SARS-CoV-2 serology was assessed by Roche Elecsys® Anti-SARS-CoV-2 immunoassay.

RESULTS

Among the 3220 participants (2444 adults, ≥18 years; 776 children, 10-17 years), the overall weighted seroprevalence was 67.3% (95% confidence intervals (CI) = 65.2, 69.3) with 71.0% in slum (95% CI = 68.7, 72.2) and 62.2% in non-slum (95% CI = 58.5, 65.8). The weighted seroprevalence was 72.9% in Dhaka and 54.2% in Chattogram. Seroprevalence was positively associated with limited years of formal education (adjusted odds ratio [aOR] = 1.61; 95% CI = 1.43, 1.82), lower income (aOR = 1.23; 95% CI = 1.03, 1.46), overweight (aOR = 1.2835; 95% CI = 1.26, 1.97), diabetes (aOR = 1.67; 95% CI = 1.21, 2.32) and heart disease (aOR = 1.38; 95% CI = 1.03, 1.86). Contrarily, negative associations were found between seropositivity and regular wearing of masks and washing hands, and prior BCG vaccination. About 63% of the population had asymptomatic infection; only 33% slum and 49% non-slum population showed symptomatic infection.

CONCLUSION

The estimated seroprevalence of SARS-CoV-2 was more prominent in impoverished informal settlements than in the adjacent middle-income non-slum areas. Additional factors associated with seropositivity included limited education, low income, overweight and pre-existing chronic conditions. Behavioral factors such as regular wearing of masks and washing hands were associated with lower probability of seropositivity.

Assessing the burden of COVID-19 in developing countries: systematic review, meta-analysis and public policy implications

INTRODUCTION

The infection fatality rate (IFR) of COVID-19 has been carefully measured and analysed in high-income countries, whereas there has been no systematic analysis of age-specific seroprevalence or IFR for developing countries.

METHODS

We systematically reviewed the literature to identify all COVID-19 serology studies in developing countries that were conducted using representative samples collected by February 2021. For each of the antibody assays used in these serology studies, we identified data on assay characteristics, including the extent of seroreversion over time. We analysed the serology data using a Bayesian model that incorporates conventional sampling uncertainty as well as uncertainties about assay sensitivity and specificity. We then calculated IFRs using individual case reports or aggregated public health updates, including age-specific estimates whenever feasible.

RESULTS

In most locations in developing countries, seroprevalence among older adults was similar to that of younger age cohorts, underscoring the limited capacity that these nations have to protect older age groups.Age-specific IFRs were roughly 2 times higher than in high-income countries. The median value of the population IFR was about 0.5%, similar to that of high-income countries, because disparities in healthcare access were roughly offset by differences in population age structure.

CONCLUSION

The burden of COVID-19 is far higher in developing countries than in high-income countries, reflecting a combination of elevated transmission to middle-aged and older adults as well as limited access to adequate healthcare. These results underscore the critical need to ensure medical equity to populations in developing countries through provision of vaccine doses and effective medications.

Confirmed SARS-CoV-2 reinfections after a second wave with predominance of Lambda in Lima and Callao, Peru

Background

Coronavirus disease 2019 (COVID-19) infection is a major public health problem in the world and reinfections are becoming more frequent. Our main objective was to describe the epidemiological, clinical, and genomic characteristics of the confirmed cases of reinfection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the capital of Lima and Callao, Peru.

Methods

We searched in the Peruvian laboratory information system from April 2020 up to May 2021, looking for cases having 2 positive molecular tests for SARS-CoV-2 with more than 90 days between them. We performed genomic sequencing to the available pairs of samples and described the clinical characteristics, epidemiological impact, and genomic analysis of the confirmed reinfections.

Results

There were 1 694 164 people with a positive diagnostic test for SARS-CoV-2 in Lima/Callao during the study period. Of these, 1695 had 2 positive molecular tests with more than 90 days between them. Two hundred eleven had both samples available for genomic analysis according to our selection criteria, and these were retrieved and submitted to sequencing. Thirty cases were confirmed to be SARS-CoV-2 reinfections with 2 different lineages in the 2 episodes. The variant Lambda (C.37) was the most common during the second infection and accounted for 19 (63.3%) of the 30 cases.

Conclusions

We report 30 cases of confirmed SARS-CoV-2 reinfections. The Lambda variant was the most common cause of the second infections, in concordance with its predominant circulation during Peru’s second wave. This report describes the largest series of confirmed reinfections by SARS-CoV-2 in Latin America.

We describe the epidemiological, clinical, and genomic characteristics of the confirmed cases of reinfection by severe acute respiratory syndrome coronavirus 2 in Lima and Callao, durante la segunda ola en Peru. The Lambda variant (C.37) was the most common cause of the second infections.

Excess all-cause deaths stratified by sex and age in Peru: a time series analysis during the COVID-19 pandemic

BACKGROUND

In this study, we estimated excess all-cause deaths and excess death rates during the COVID-19 pandemic in 25 Peruvian regions, stratified by sex and age group.

DESIGN

Cross-sectional study.

SETTING

Twenty-five Peruvian regions with complete mortality data.

PARTICIPANTS

Annual all-cause official mortality data set from SINADEF (Sistema Informático Nacional de Defunciones) at the Ministry of Health of Peru for 2017-2020, disaggregated by age and sex.

MAIN OUTCOME MEASURES

Excess deaths and excess death rates (observed deaths vs expected deaths) in 2020 by sex and age (0-29, 30-39, 40-49, 50-59, 60-69, 70-79 and ≥80 years) were estimated using P-score. The ORs for excess mortality were summarised with a random-effects meta-analysis.

RESULTS

In the period between January and December 2020, we estimated an excess of 68 608 (117%) deaths in men and 34 742 (69%) deaths in women, corresponding to an excess death rate of 424 per 100 000 men and 211 per 100 000 women compared with the expected mortality rate. The number of excess deaths increased with age and was higher in men aged 60-69 years (217%) compared with women (121%). Men between the ages of 40 and 79 years experienced twice the rate of excess deaths compared with the expected rate. In eight regions, excess deaths were higher than 100% in men, and in seven regions excess deaths were higher than 70% in women. Men in eight regions and women in one region had two times increased odds of excess death than the expected mortality. There were differences in excess mortality according to temporal distribution by epidemiological week.

CONCLUSION

Approximately 100 000 excess all-cause deaths occurred in 2020 in Peru. Age-stratified excess death rates were higher in men than in women. There was strong excess in geographical and temporal mortality patterns according to region.

The SARS-CoV-2 pandemic in Germany may represent the sum of a large number of local but independent epidemics each initiated by individuals aged 10 - 19 years, middle aged males, or elderly individuals

Many epidemiological aspects of the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) pandemics, particularly those affecting children, are still sparsely elucidated. Data on the first pandemic phase during the year 2020 indicated that children might serve as a virus reservoir. We now analyzed data on more than 530 000 SARS‐CoV‐2 polymerase chain reaction (PCR) and 12 503 anti‐SARS‐CoV‐2 antibody tests performed in the west of Germany until Week 4 of 2021. We show that children of at least 10 years of age may play a prominent role in the pandemic showing highest PCR‐positive rates in the first (Weeks 28–35), second (Weeks 42–48), and third wave (Week 50 of 2020–Week 2 2021) of the second pandemic phase, although the waves were not mainly initiated by children. The waves' kinetics differed even in nearby cities. Low PCR‐positive rates were confined to areas of lower population density. PCR‐positive rates were higher among middle‐aged males compared with women and among very old females compared with males. From Week 25, seroprevalence rates slowly increased to 50%, indicating ongoing virus activity. In conclusion, the SARS‐CoV‐2 pandemics is characterized by many local but interacting epidemics, initiated and driven by different social groups. Children may not be the main initiators of virus spreading but older children may significantly affect the course of the pandemic. High population density is associated with higher SARS‐CoV‐2 incidence.

Nationally representative SARS-CoV-2 antibody prevalence estimates after the first epidemic wave in Mexico

Seroprevalence surveys provide estimates of the extent of SARS-CoV-2 infections in the population, regardless of disease severity and test availability. In Mexico in 2020, COVID-19 cases reached a maximum in July and December. We aimed to estimate the national and regional seroprevalence of SARS-CoV-2 antibodies across demographic and socioeconomic groups in Mexico after the first wave, from August to November 2020. We used nationally representative survey data including 9,640 blood samples. Seroprevalence was estimated by socioeconomic and demographic characteristics, adjusting by the sensitivity and specificity of the immunoassay test. The national seroprevalence of SARS-CoV-2 antibodies was 24.9% (95%CI 22.2, 26.7), being lower for adults 60 years and older. We found higher seroprevalence among urban and metropolitan areas, low socioeconomic status, low education and workers. Among seropositive people, 67.3% were asymptomatic. Social distancing, lockdown measures and vaccination programs need to consider that vulnerable groups are more exposed to the virus and unable to comply with lockdown measures.

SARS-CoV-2 seroprevalence surveys provide estimates of the extent of prior infection in a population. In this nationally representative survey from Mexico, the authors estimate seroprevalence after the first epidemic wave at ~25%, with variation by region, age, socioeconomic status, and education level.

Nationally representative SARS-CoV-2 antibody prevalence estimates after the first epidemic wave in Mexico

Seroprevalence surveys provide estimates of the extent of SARS-CoV-2 infections in the population, regardless of disease severity and test availability. In Mexico in 2020, COVID-19 cases reached a maximum in July and December. We aimed to estimate the national and regional seroprevalence of SARS-CoV-2 antibodies across demographic and socioeconomic groups in Mexico after the first wave, from August to November 2020. We used nationally representative survey data including 9,640 blood samples. Seroprevalence was estimated by socioeconomic and demographic characteristics, adjusting by the sensitivity and specificity of the immunoassay test. The national seroprevalence of SARS-CoV-2 antibodies was 24.9% (95%CI 22.2, 26.7), being lower for adults 60 years and older. We found higher seroprevalence among urban and metropolitan areas, low socioeconomic status, low education and workers. Among seropositive people, 67.3% were asymptomatic. Social distancing, lockdown measures and vaccination programs need to consider that vulnerable groups are more exposed to the virus and unable to comply with lockdown measures.

Seroprevalence, spatial distribution, and social determinants of SARS-CoV-2 in three urban centers of Chile

BACKGROUND

Seroprevalence studies provide an accurate measure of SARS-CoV-2 spread and the presence of asymptomatic cases. They also provide information on the uneven impact of the pandemic, pointing out vulnerable groups to prioritize which is particularly relevant in unequal societies. However, due to their high cost, they provide limited evidence of spatial spread of the pandemic specially in unequal societies. Our objective was to estimate the prevalence of SARS-CoV-2 antibodies in Chile and model its spatial risk distribution.

METHODS

During Oct-Nov 2020, we conducted a population-based serosurvey in Santiago, Talca, and Coquimbo-La Serena (2493 individuals). We explored the individual association between positive results and socio-economic and health-related variables by logistic regression for complex surveys. Then, using an Empirical Bayesian Kriging model, we estimated the infection risk spatial distribution using individual and census information, and compared these results with official records.

RESULTS

Seroprevalence was 10.4% (95% CI 7.8-13.7%), ranging from 2% (Talca) to 11% (Santiago), almost three times the number officially reported. Approximately 36% of these were asymptomatic, reaching 82% below 15 years old. Seroprevalence was associated with the city of residence, previous COVID-19 diagnosis, contact with confirmed cases (especially at household), and foreign nationality. The spatial model accurately interpolated the distribution of disease risk within the cities finding significant differences in the predicted probabilities of SARS-CoV-2 infection by census zone (IQR 2.5-15.0%), related to population density and education.

CONCLUSIONS

Our results underscore the transmission heterogeneity of SARS-CoV-2 within and across three urban centers of Chile. Socio-economic factors and the outcomes of this seroprevalence study enable us to identify priority areas for intervention. Our methodological approach and results can help guide the design of interdisciplinary strategies for urban contexts, not only for SARS-CoV-2 but also for other communicable diseases.

COVID-19 and inequities in the Americas: lessons learned and implications for essential health services

The COVID-19 pandemic has exacerbated social, economic, and health-related disparities, which disproportionately affect persons living in conditions of vulnerability. Such populations include ethnic groups who face discrimination and experience barriers to accessing comprehensive health care. The COVID-19 pandemic has exposed these health disparities, and disruptions of essential health services have further widened the gaps in access to health care. Noncommunicable diseases are more prevalent among groups most impacted by poor social determinants of health and have been associated with an increased likelihood of severe COVID-19 disease and higher mortality. Disruptions in the provision of essential health services for noncommunicable diseases, mental health, communicable diseases such as HIV, tuberculosis, and malaria, and maternal and child health services (including sexual and reproductive health), are projected to also increase poor health outcomes. Other challenges have been an increased frequency of interpersonal violence and food insecurity. Countries in the Americas have responded to the disruptions caused by the pandemic by means of health service delivery through telemedicine and other digital solutions and stepping up social service support interventions. As vaccinations for COVID-19 create the opportunity to overcome the pandemic, countries must strengthen primary health care and essential health services with a view to ensuring equity, if the region is to achieve universal health coverage in fulfillment of the Sustainable Development Goals.

Territorial Strategy of Medical Units for Addressing the First Wave of the COVID-19 Pandemic in the Metropolitan Area of Mexico City: Analysis of Mobility, Accessibility and Marginalization

BACKGROUND

The COVID-19 pandemic has caused an exponential increase in the demand for medical care worldwide. In Mexico, the COVID Medical Units (CMUs) conversion strategy was implemented.

OBJECTIVE

To evaluate the CMU coverage strategy in the Mexico City Metropolitan Area (MCMA) by territory.

MATERIALS

The CMU directory was used, as were COVID-19 infection and mobility statistics and Mexican 2020 census information at the urban geographic area scale. The degree of urban marginalization by geographic area was also considered.

METHOD

Using descriptive statistics and the calculation of a CMU accessibility index, population aggregates were counted based on coverage radii. In addition, two regression models are proposed to explain (1) the territorial and temporal trend of COVID-19 infections in the MCMA and (2) the mobility of the COVID-infected population visiting medical units.

RESULTS

The findings of the evaluation of the CMU strategy were (1) in the MCMA, COVID-19 followed a pattern of contagion from the urban center to the periphery; (2) given the growth in the number of cases and the overload of medical units, the population traveled greater distances to seek medical care; (3) after the CMU strategy was evaluated at the territory level, it was found that 9 out of 10 inhabitants had a CMU located approximately 7 km away; and (4) at the metropolitan level, the lowest level of accessibility to the CMU was recorded for the population with the highest levels of marginalization, i.e., those residing in the urban periphery.

Asymptomatic SARS-COV-2 carriage and sero-positivity in high risk contacts of COVID-19 cases'

Purpose

Identifying asymptomatic SARS-COV-2 carriage is one of the crucial factors in controlling the COVID 19 pandemic. The relationship between the asymptomatic viral carriage and the rate of seroconversion needs better understanding. The present study was conducted to identify the asymptomatic COVID-19 infection and seropositivity in high-risk contacts in the southern district of Delhi, India.

Methods

Following the screening of 6961 subjects, a total of 407 asymptomatic high-risk subjects were selected. Demographic data, socioeconomic status, and history of COVID-19 related symptoms in the last 4 months were recorded. Blood samples and Nasopharyngeal/oropharyngeal swabs were collected for the detection of SARS-COV-2 RNA and anti-SARS-COV-2 antibodies.

Results

55 asymptomatic high-risk subjects (13.5%) tested positive for SARS-COV-2 infection and among them, 70.9% remained asymptomatic throughout their course of infection. The seropositivity among the subjects was 28.9% (n ​= ​118) and was found significantly higher among lower-middle socioeconomic strata (p ​= ​0.01). The antibody levels were significantly higher (p ​= ​0.033) in individuals with a previous history of COVID-19 like symptoms as compared to the subjects, who had no such history. Asymptomatic healthcare workers showed a significantly increased rate of SARS-COV-2 infection (p ​= ​0.004) and seropositivity (p ​= ​0.005) as compared to the non-healthcare workers. Subjects, who were exposed to infection at their workplace (non-hospital setting) had the least RT-PCR positivity rate (p ​= ​0.03).

Conclusions

A large proportion of SARS-COV-2 infection remains completely asymptomatic. The rate of asymptomatic carriage and seropositivity is significantly higher in healthcare workers as compared to the general population. The level of SARS-COV-2 antibodies is directly related to the appearance of symptoms. These observations may contribute to redefining COVID 19 screening, infection control, and professional health practice strategies.

SARS-CoV-2 infections in households in a peri-urban community of Lima, Peru: A prospective cohort study

Background

We assessed the prevalence and incidence of SARS‐CoV‐2 infections in a prospective study of households in Lima, Peru.

Methods

Households with a child, a young adult 18–50 years, and an adult age >50 years in peri‐urban Lima were followed with twice‐a‐week household visits during a 2‐month period. Nasal swabs and saliva specimens were collected twice weekly, and nasopharyngeal swabs were collected weekly from each participant, regardless of symptoms. Laboratory‐confirmed SARS‐CoV‐2 infection was defined by two RT‐PCR tests from any of the collected specimens within a week. Blood samples collected at enrollment and end of follow‐up were tested with rapid serological tests. We calculated the prevalence and incidence of laboratory‐confirmed SARS‐CoV‐2 infections.

Results

We enrolled 132 participants from 44 households: 44 children, 44 young adults, and 44 older adults. A total of 13 SARS‐CoV‐2 infections were detected in eight households, for an overall period prevalence of 9.85% (95% confidence interval [CI]: 5.35–16.25). Most (61.54%) infections were symptomatic. Eight of 11 (72.73%) SARS‐CoV‐2 detections corresponded to the Lambda variant. During 218.79 person‐months at risk of follow‐up, there were six new SARS‐CoV‐2 infections detected (2.74 per 100 person‐month, 95% CI: 1.25–6.04). At enrollment, 59 of 128 participants tested had positive SARS‐CoV‐2 IgG serology (46.09%, 95% CI: 37.25–55.12). Five of six new infections occurred among participants with negative baseline serology.

Conclusions

We demonstrated high incidence of SARS‐CoV‐2 infections in households, especially among subjects without evidence of prior infection, most of them not detected by the Ministry of Health system.

High SARS-CoV-2 Seroprevalence in Rural Peru, 2021: a Cross-Sectional Population-Based Study

Latin America has been severely affected by the COVID-19 pandemic. The COVID-19 burden in rural settings in Latin America is unclear. We performed a cross-sectional, population-based, random-selection SARS-CoV-2 serologic study during March 2021 in the rural population of San Martin region, northern Peru. In total, 563 persons from 288 houses across 10 provinces were enrolled, reaching 0.2% of the total rural population of San Martin. Screening for SARS-CoV-2 IgG antibodies was done using a chemiluminescence immunoassay (CLIA), and reactive sera were confirmed using a SARS-CoV-2 surrogate virus neutralization test (sVNT). Validation of the testing algorithm using prepandemic sera from two regions of Peru showed false-positive results in the CLIA (23/84 sera; 27%) but not in the sVNT, highlighting the pitfalls of SARS-CoV-2 antibody testing in tropical regions and the high specificity of the two-step algorithm used in this study. An overall 59.0% seroprevalence (95% confidence interval [CI], 55 to 63%) corroborated intense SARS-CoV-2 spread in San Martin. Seroprevalence rates between the 10 provinces varied from 41.3 to 74.0% (95% CI, 30 to 84%). Higher seroprevalence was not associated with population size, population density, surface area, mean altitude, or poverty index in Spearman correlations. Seroprevalence and reported incidence diverged substantially between provinces, suggesting regional biases of COVID-19 surveillance data. Potentially, limited health care access due to environmental, economic, and cultural factors might lead to undetected infections in rural populations. Additionally, test avoidance to evade mandatory quarantine might affect rural regions more than urban regions. Serologic diagnostics should be pursued in resource-limited settings to inform country-level surveillance and vaccination strategies and to support control measures for COVID-19.

IMPORTANCE Latin America is a global hot spot of the COVID-19 pandemic. Serologic studies in Latin America have been mostly performed in urban settings. Rural populations comprise 20% of the total Latin American population. Nevertheless, information on COVID-19 spread in rural settings is scarce. Using a representative population-based seroprevalence study, we detected a high seroprevalence in rural populations in San Martin, northern Peru, in 2021, reaching 41 to 74%. However, seroprevalence and reported incidence diverged substantially between regions, potentially due to limited health care access or test avoidance due to mandatory quarantine. Our results suggest that rural populations are highly affected by SARS-CoV-2 even though they are sociodemographically distinct from urban populations and that highly specific serological diagnostics should be performed in resource-limited settings to support public health strategies of COVID-19 control.

Household overcrowding and risk of SARS-CoV-2: analysis of the Virus Watch prospective community cohort study in England and Wales

Background: Household overcrowding is associated with increased risk of infectious diseases across contexts and countries. Limited data exist linking household overcrowding and risk of COVID-19. We used data collected from the Virus Watch cohort to examine the association between overcrowded households and SARS-CoV-2. Methods: The Virus Watch study is a household community cohort of acute respiratory infections in England and Wales. We calculated overcrowding using the measure of persons per room for each household. We considered two primary outcomes: PCR-confirmed positive SARS-CoV-2 antigen tests and laboratory-confirmed SARS-CoV-2 antibodies. We used mixed-effects logistic regression models that accounted for household structure to estimate the association between household overcrowding and SARS-CoV-2 infection. Results:26,367 participants were included in our analyses. The proportion of participants with a positive SARS-CoV-2 PCR result was highest in the overcrowded group (9.0%; 99/1,100) and lowest in the under-occupied group (4.2%; 980/23,196). In a mixed-effects logistic regression model, we found strong evidence of an increased odds of a positive PCR SARS-CoV-2 antigen result (odds ratio 2.45; 95% CI:1.43-4.19; p-value=0.001) and increased odds of a positive SARS-CoV-2 antibody result in individuals living in overcrowded houses (3.32; 95% CI:1.54-7.15; p-value<0.001) compared with people living in under-occupied houses. Conclusion:Public health interventions to prevent and stop the spread of SARS-CoV-2 should consider the risk of infection for people living in overcrowded households and pay greater attention to reducing household transmission.

Maternal-fetal immunologic response to SARS-CoV-2 infection in a symptomatic vulnerable population: A prospective cohort

BACKGROUND

COVID-19 disproportionally affects pregnant women and their newborn, yet little is known about the variables that modulate the maternal-fetal immune response to infection.

METHODS

We prospectively studied socioeconomic, biologic and clinical factors affecting humoral immunity in 87 unvaccinated pregnant women admitted to hospital in the Buenos Aires metropolitan area for symptoms consistent with COVID-19 disease.

RESULTS

The number of days between symptom onset and childbirth predicted maternal and newborn virus Spike protein Receptor Binding Domain (RBD)-specific IgG. These findings suggest newborns may benefit less when mothers deliver soon after COVID-19 infection. Similarly, a longer time between symptom onset and birth predicted higher in utero transfer of maternal IgG and its concentration in cord blood. Older gestational ages at birth were associated with lower maternal IgG: cord blood IgG ratios. Eighty seven percent of women with confirmed SARS-CoV-2 infection developed RBD-specific IgA responses in breast milk within 96 h of childbirth. IgA was not significantly associated with time from infection but correlated with maternal serum IgG and placental transfer.

CONCLUSIONS

These results demonstrate the combined role of biologic, clinical and socioeconomic variables associated with maternal SARS-CoV-2 RBD-specific antibodies and supports early vaccination strategies for COVID-19 in socioeconomically vulnerable pregnant women.

From pandemic response to portable population health: A formative evaluation of the Detroit mobile health unit program

This article describes our experience developing a novel mobile health unit (MHU) program in the Detroit, Michigan, metropolitan area. Our main objectives were to improve healthcare accessibility, quality and equity in our community during the novel coronavirus pandemic. While initially focused on SARS-CoV-2 testing, our program quickly evolved to include preventive health services. The MHU program began as a location-based SARS-CoV-2 testing strategy coordinated with local and state public health agencies. Community needs motivated further program expansion to include additional preventive healthcare and social services. MHU deployment was targeted to disease "hotspots" based on publicly available SARS-CoV-2 testing data and community-level information about social vulnerability. This formative evaluation explores whether our MHU deployment strategy enabled us to reach patients from communities with heightened social vulnerability as intended. From 3/20/20-3/24/21, the Detroit MHU program reached a total of 32,523 people. The proportion of patients who resided in communities with top quartile Centers for Disease Control and Prevention Social Vulnerability Index rankings increased from 25% during location-based "drive-through" SARS-CoV-2 testing (3/20/20-4/13/20) to 27% after pivoting to a mobile platform (4/13/20-to-8/31/20; p = 0.01). The adoption of a data-driven deployment strategy resulted in further improvement; 41% of the patients who sought MHU services from 9/1/20-to-3/24/21 lived in vulnerable communities (Cochrane Armitage test for trend, p<0.001). Since 10/1/21, 1,837 people received social service referrals and, as of 3/15/21, 4,603 were administered at least one dose of COVID-19 vaccine. Our MHU program demonstrates the capacity to provide needed healthcare and social services to difficult-to-reach populations from areas with heightened social vulnerability. This model can be expanded to meet emerging pandemic needs, but it is also uniquely capable of improving health equity by addressing longstanding gaps in primary care and social services in vulnerable communities.

Inferring the COVID-19 infection fatality rate in the community-dwelling population: a simple Bayesian evidence synthesis of seroprevalence study data and imprecise mortality data

Estimating the coronavirus disease-2019 (COVID-19) infection fatality rate (IFR) has proven to be particularly challenging –and rather controversial– due to the fact that both the data on deaths and the data on the number of individuals infected are subject to many different biases. We consider a Bayesian evidence synthesis approach which, while simple enough for researchers to understand and use, accounts for many important sources of uncertainty inherent in both the seroprevalence and mortality data. With the understanding that the results of one's evidence synthesis analysis may be largely driven by which studies are included and which are excluded, we conduct two separate parallel analyses based on two lists of eligible studies obtained from two different research teams. The results from both analyses are rather similar. With the first analysis, we estimate the COVID-19 IFR to be 0.31% [95% credible interval (CrI) of (0.16%, 0.53%)] for a typical community-dwelling population where 9% of the population is aged over 65 years and where the gross-domestic-product at purchasing-power-parity (GDP at PPP) per capita is $17.8k (the approximate worldwide average). With the second analysis, we obtain 0.32% [95% CrI of (0.19%, 0.47%)]. Our results suggest that, as one might expect, lower IFRs are associated with younger populations (and may also be associated with wealthier populations). For a typical community-dwelling population with the age and wealth of the United States we obtain IFR estimates of 0.43% and 0.41%; and with the age and wealth of the European Union, we obtain IFR estimates of 0.67% and 0.51%.

Epidemiological Analysis of COVID-19 Cases in Native Amazonian Communities from Peru

Despite early control measures, SARS-CoV-2 reached all regions of Peru during the first wave of the pandemic, including native communities of the Peruvian Amazon. Here, we aimed to describe the epidemiological situation of COVID-19 in the Amazonas region of Peru using an open database of 11,124 COVID-19 cases reported from 19 March to 29 July 2020, including 3278 cases from native communities. A high-incidence area in northern Amazonas (Condorcanqui) reported a cumulative incidence of 63.84/1000 inhabitants with a much lower death rate (0.95%) than the national average. Our results showed at least eight significant factors for mortality, and the Native Amazonian ethnicity as a protective factor. Molecular confirmatory tests are necessary to better explain the high incidence of antibody response reported in these communities.

Estimation of all-cause excess mortality by age-specific mortality patterns for countries with incomplete vital statistics: a population-based study of the case of Peru during the first wave of the COVID-19 pandemic

BACKGROUND

All-cause excess mortality is a comprehensive measure of the combined direct and indirect effects of COVID-19 on mortality. Estimates are usually derived from Civil Registration and Vital Statistics (CRVS) systems, but these do not include non-registered deaths, which may be affected by changes in vital registration coverage over time.

METHODS

Our analytical framework and empirical strategy account for registered mortality and under-registration. This provides a better estimate of the actual mortality impact of the first wave of the COVID-19 pandemic in Peru. We use population and crude mortality rate projections from Peru's National Institute of Statistics and Information (INEI, in Spanish), individual-level registered COVID-19 deaths from the Ministry of Health (MoH), and individual-level registered deaths by region and age since 2017 from the National Electronic Deaths Register (SINADEF, in Spanish).We develop a novel framework combining different estimates and using quasi-Poisson models to estimate total excess mortality across regions and age groups. Also, we use logistic mixed-effects models to estimate the coverage of the new SINADEF system.

FINDINGS

We estimate that registered mortality underestimates national mortality by 37•1% (95% CI 23% - 48•5%) across 26 regions and nine age groups. We estimate total all-cause excess mortality during the period of analysis at 173,099 (95% CI 153,669 - 187,488) of which 108,943 (95% CI 96,507 - 118,261) were captured by the vital registration system. Deaths at age 60 and over accounted for 74•1% (95% CI 73•9% - 74•7%) of total excess deaths, and there were fewer deaths than expected in younger age groups. Lima region, on the Pacific coast and including the national capital, accounts for the highest share of excess deaths, 87,781 (95% CI 82,294 - 92,504), while in the opposite side regions of Apurimac and Huancavelica account for less than 300 excess deaths.

INTERPRETATION

Estimating excess mortality in low- and middle-income countries (LMICs) such as Peru must take under-registration of mortality into account. Combining demographic trends with data from administrative registries reduces uncertainty and measurement errors. In countries like Peru, this is likely to produce significantly higher estimates of excess mortality than studies that do not take these effects into account.

FUNDING

None.

SARS-CoV-2 seroprevalence in a high-altitude setting in Peru: adult population-based cross-sectional study

BACKGROUND

There are several ecological studies, but few studies of the prevalence of SARS-COV-2 at high altitude. We aimed to estimate the population-based seroprevalence of SARS-COV-2 in three settings of Cusco at the end of the first wave among adults.

METHODS

A population-based survey was conducted in September 2020, in three settings in the region of Cusco: (1) Cusco city at 3,300 meters above the sea level (m.a.s.l.), (2) the periphery of Cusco (Santiago, San Jerónimo, San Sebastián, and Wanchaq) at 3,300 m.a.s.l., and (3) Quillabamba city, located at 1,050 m.a.s.l. People aged ≥ 18 years within a family unit were included. The diagnosis of SARS-CoV-2 infection was based on identifying anti- SARS-CoV-2 total antibodies (IgM and IgG) in serum using the Elecsys Anti-SARS-CoV-2 chemiluminescence test.

RESULTS

We enrolled 1924 participants from 712 families. Of the total, 637 participants were anti-SARS-CoV-2 seropositive. Seroprevalence was 38.8% (95% CI [33.4%-44.9%]) in Cusco city, 34.9% (95% CI [30.4%-40.1%]) in the periphery of Cusco, and 20.3% (95% CI [16.2%-25.6%]) in Quillabamba. In 141 families (19.8%; 95% CI [17.0%-22.8%]) the whole members were positive to the test. Living with more than three persons in the same house, a positive COVID-19 case at home, and a member who died in the last five months were factors associated with SARS-COV-2 seropositivity. Dysgeusia/dysosmia was the symptom most associated with seropositivity (aPR = 2.74, 95% CI [2.41-3.12]); whereas always wearing a face shield (aPR = 0. 73; 95% CI [0.60-0.89]) or a facial mask (aPR = 0.76, 95% CI [0.63-0. 92) reduced that probability.

CONCLUSIONS

A great proportion of Cusco's city inhabitants presented anti-SARS-CoV-2 antibodies at the end of the first wave, with significant differences between settings. Wearing masks and face shields were associated with lower rate of seropositivity; however, efforts must be made to sustain them over time since there is still a high proportion of susceptible people.

Improving Social Justice in COVID-19 Health Research: Interim Guidelines for Reporting Health Equity in Observational Studies

The COVID-19 pandemic has highlighted the global imperative to address health inequities. Observational studies are a valuable source of evidence for real-world effects and impacts of implementing COVID-19 policies on the redistribution of inequities. We assembled a diverse global multi-disciplinary team to develop interim guidance for improving transparency in reporting health equity in COVID-19 observational studies. We identified 14 areas in the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) checklist that need additional detail to encourage transparent reporting of health equity. We searched for examples of COVID-19 observational studies that analysed and reported health equity analysis across one or more social determinants of health. We engaged with Indigenous stakeholders and others groups experiencing health inequities to co-produce this guidance and to bring an intersectional lens. Taking health equity and social determinants of health into account contributes to the clinical and epidemiological understanding of the disease, identifying specific needs and supporting decision-making processes. Stakeholders are encouraged to consider using this guidance on observational research to help provide evidence to close the inequitable gaps in health outcomes.

Integration of symptomatic, demographical and diet-related comorbidities data with SARS-CoV-2 antibody rapid diagnostic tests during epidemiological surveillance: a cross-sectional study in Jakarta, Indonesia

OBJECTIVES

Affordable options for COVID-19 epidemiological surveillance are needed. Virus detection by reverse transcription-PCR (RT-PCR) is sensitive but costly, and antigen-based rapid diagnostic tests (RDTs) are cheap but with reduced sensitivity; both detect current infection but not exposure. RDT-IgM/IgG antibodies to SARS-CoV-2 detect exposure but have poor sensitivity for current infection. We investigated if the integration of symptomatic, demographical and diet-related comorbidities data with antibody RDTs improves their potential to assess infection rates in addition to exposure, thereby broadening their utility for surveillance.

DESIGN

We conducted a cross-sectional study using data from community surveillance for SARS-CoV-2. Health workers collected nasopharyngeal swabs for RT-PCR and RDT antigen assessments and venous blood for RDT-IgM/IgG from symptomatic and asymptomatic persons. Data on age, gender, contact history, symptoms (ie, fever, cough, runny nose, sore throat, headache, dyspnoea and diarrhoea), diet-related comorbidities (ie, diabetes and hypertension) and chest radiology were collected.

SETTING

High-risk communities in Jakarta, Indonesia, in May 2020.

PARTICIPANTS

343 community members' data were included.

OUTCOME MEASURES

RDT-IgM/IgG sensitivity, specificity and predictive values and area under receiver operating characteristic curve for RT-PCR positivity using RDT results alone and in combination with other predictors, including symptom components derived from principal component analysis.

RESULTS

There were 24 PCR-confirmed infections. RDT-IgM/IgG-positive tests were associated with infection (OR 10.8, 95% CI 4.43 to 26.4, p<0.001) with an area under the curve (AUC) of 0.708% and 50% sensitivity, 91.5% specificity, 30.8% positive predictive value (PPV) and 96.1% negative predictive value (NPV). RDT results combined with age, gender, contact history, symptoms and comorbidities increased the AUC to 0.787 and yielded 62.5% sensitivity, 87.0% specificity, 26.6% PPV and 96.9% NPV.

CONCLUSIONS

SARS-CoV-2 RDT-IgM/IgG results integrated with other predictors may be an affordable tool for epidemiological surveillance for population-based COVID-19 exposure and current infection, especially in groups with outbreaks or high transmission.

SARS-CoV-2 in eight municipalities of the Colombian tropics: high immunity, clinical and sociodemographic outcomes

Background

Serological evaluation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an alternative that allows us to determine the prevalence and dynamics of this infection in populations. The goal of this study was to determine the clinical and sociodemographic dynamics of SARS-CoV-2 infection in a region of the Colombian Caribbean.

Methods

Between July and November 2020, a cross-sectional observational study was carried out in Córdoba, located in northeast Colombia in the Caribbean area. Eight municipalities with the largest populations were chosen and 2564 blood samples were taken. A commercial enzyme-linked immunosorbent assay was used with the recombinant protein antigen N of SARS-CoV-2. The people included in the study were asked for sociodemographic and clinical data, which were analysed by statistical methods.

Results

A seroprevalence of 40.8% was obtained for SARS-CoV-2 in the Córdoba region. In the bivariate analysis, no differences were observed in seropositivity against SARS-CoV-2 for gender or age range (p>0.05). Higher seropositivity was found in low socio-economic status and symptomatic patients (p<0.0001). A total of 30.7% of the asymptomatic patients were seropositive for SARS-CoV-2, which could be linked to the spread of this infection. In the multivariate analysis, seroconversion was related to poverty and clinical manifestations such as anosmia and ageusia (p<0.05).

Conclusions

The high seropositivity in Córdoba is due to widespread SARS-CoV-2 in this population. The relationship between seropositivity and socio-economic status suggests a higher exposure risk to the virus caused by informal economic activities in low-income groups. Clinical manifestations such as anosmia and ageusia could be clinical predictors of infection by the new emergent coronavirus.

Seroprevalence of SARS-CoV-2 Infection and Adherence to Preventive Measures in Cuenca, Ecuador, October 2020, a Cross-Sectional Study

A door-to-door survey was organised in Cuenca, Ecuador, to determine the prevalence of COVID-19 infection and adherence of the population to COVID-19 preventive measures. A total of 2457 persons participated in the study; 584 (23.7%) reported having experienced at least one flu-like symptom since the onset of the pandemic. The maximum SARS-CoV-2 seroprevalence in Cuenca was 13.2% (CI: 12-14.6%) (IgM or IgG positive). Considering PCR confirmed infections, the prevalence was 11% (CI: 10-12.4%). There was no significant difference in seroprevalence between rural and urban areas. Participants aged 35-49 years old, living with a COVID-19 positive person, at least six people in a household, physical contact with someone outside the household, a contact with a person outside the home with flu-like symptoms, using public transport, and not having enough resources for living, significantly increased the odds for SARS-CoV-2 seropositivity. Overall, there was good adherence to COVID-19 preventive measures. Having known someone who tested positive for COVID-19, having a primary or secondary level of education, and having enough resources for living, significantly increased the odds for higher adherence. In conclusion, despite good overall adherence of the population of Cuenca with COVID-19 preventive measures, our study suggests high ongoing COVID-19 transmission in Cuenca, particularly in certain parishes. Prevention should not only focus on behavioural change, but on intensified testing strategies in demographical risk groups.