High seroprevalence for SARS-CoV-2 infection in South America, but still not enough for herd immunity!

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.

High seroprevalence of severe acute respiratory syndrome coronavirus 2 among healthcare workers in Yaoundé, Cameroon after the first wave of Covid-19 pandemic and associated factors

BACKGROUND

Healthcare workers (HWs) are at a high risk of exposure to emerging health threats. Following the first wave of the coronavirus disease 2019 pandemic in Cameroon, we explored the presence and persistence of naturally acquired antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the factors associated with seropositivity in HWs.

METHODS

Staff at two referral hospitals in Yaoundé or two Health District Hospitals in Obala and Mbalmayo were included in a 6-month prospective cohort analysis or cross-sectional survey, respectively. Seroprevalence and associated factors were determined, and Kaplan-Meier curves and Cox proportional hazards models were used to assess antibody persistence or positive seroconversion over time.

RESULTS

From August 2020 to March 2021, 426 HWs (median age: 31 years, interquartile range: 27-37 years; 66.4% female) were enrolled. The overall seroprevalence of anti-SARS-CoV-2 antibodies was 54.0% (95% confidence interval [CI]: 49.1-58.8) and was significantly different between study sites (p = 0.04). Of the 216 HWs included in the 6-month cohort, 109 (50.5%) HWs were seropositive at inclusion; the probability of persistent antibodies or of becoming seropositive was 93.8% (95% CI: 84.2-100) and 78.9% (95% CI: 61.7-88.4), respectively. Seroconversion was associated with study site and occupation but not with infection prevention and control (IPC) practices.

CONCLUSIONS

We observed high seroprevalence of SARS-CoV-2 antibody and seroconversion among HWs associated with occupational risk. This suggests low compliance to the COVID-19 control measures. Continued training and implementation of IPC measures and accelerated preparedness are needed to better tackle future threats.

Severe acute respiratory syndrome coronavirus 2 seroprevalence among patients with pulmonary tuberculosis

OBJECTIVE

The objective of this study was to estimate the seroprevalence of severe acute respiratory syndrome coronavirus 2 antibodies in patients with tuberculosis.

METHODS

This cross-sectional study was conducted at an outpatient tuberculosis clinic in Alvorada, RS, Brazil, with data collection between October and December 2020. Outpatients aged>18 years with active pulmonary tuberculosis, no prior history of coronavirus disease 2019, and no suspected coronavirus disease 2019 were included in the study. Whole blood samples were collected to perform the severe acute respiratory syndrome coronavirus 2 antibodies test.

RESULTS

During the study period, 52 patients met the inclusion and were included in the analysis. Severe acute respiratory syndrome coronavirus 2 antibodies were positive in 16 (30.8%) patients. Male sex was more frequent among patients with negative severe acute respiratory syndrome coronavirus 2 antibodies than in patients with positive severe acute respiratory syndrome coronavirus 2 antibodies (86.1 vs. 56.3%, p=0.031). Contact with coronavirus disease 2019 case was more common in patients with positive severe acute respiratory syndrome coronavirus 2 antibodies compared with patients with negative severe acute respiratory syndrome coronavirus 2 antibodies (87.5 vs. 8.3%, p<0.0001). In a multivariate analysis, in a model including the variables such as male sex and contact with coronavirus disease 2019 case, only contact with coronavirus disease 2019 was independently associated with positive severe acute respiratory syndrome coronavirus 2 antibodies (OR 77.0, 95%CI 11.5-512.4, p<0.0001).

CONCLUSION

This study revealed a seroprevalence of 30.8% severe acute respiratory syndrome coronavirus 2 among patients with tuberculosis.

Population-Level Immunity for Transient Suppression of COVID-19 Waves in Japan from April 2021 to September 2022

Multiple COVID-19 waves have been observed worldwide, with varying numbers of positive cases. Population-level immunity can partly explain a transient suppression of epidemic waves, including immunity acquired after vaccination strategies. In this study, we aimed to estimate population-level immunity in 47 Japanese prefectures during the three waves from April 2021 to September 2022. For each wave, characterized by the predominant variants, namely, Delta, Omicron, and BA.5, the estimated rates of population-level immunity in the 10-64-years age group, wherein the most positive cases were observed, were 20%, 35%, and 45%, respectively. The number of infected cases in the BA.5 wave was inversely associated with the vaccination rates for the second and third injections. We employed machine learning to replicate positive cases in three Japanese prefectures to validate the reliability of our model for population-level immunity. Using interpolation based on machine learning, we estimated the impact of behavioral factors and vaccination on the fifth wave of new positive cases that occurred during the Tokyo 2020 Olympic Games. Our computational results highlighted the critical role of population-level immunity, such as vaccination, in infection suppression. These findings underscore the importance of estimating and monitoring population-level immunity to predict the number of infected cases in future waves. Such estimations that combine numerical derivation and machine learning are of utmost significance for effective management of medical resources, including the vaccination strategy.

Safety of International Professional Sports Competitions During the COVID-19 Pandemic: The Association Football Experience

Major sporting events were suspended during the most acute phase of the COVID-19 pandemic. Competitions are resuming with enhanced hygiene protocols and altered mechanics. While risks for players and staff have been studied, the impact of large-scale tournaments on the communities that host them remains largely unstudied. CONMEBOL Copa América is one of the first wide-scale international tournaments to be conducted in its original format since the beginning of the COVID-19 pandemic. The tournament saw 10 national teams compete in four Brazilian cities during a period of heightened viral transmission. The analysis of over 28,000 compulsory PCR tests showed that positive cases did not lead to the uncontrolled spread of the disease among staff and players. More importantly, the data indicate that locally hired staff were not exposed to increased risk while working. The Copa América experience shows that international sporting competitions can be conducted safely even under unfavourable epidemiological situations.

Effectiveness of the BBIBP-CorV vaccine in preventing infection and death in health care workers in Peru 2021

BACKGROUND

During 2021, Peru started the vaccination against SARS-CoV-2 using the BBIBP-CorV inactivated virus vaccine for health care workers (HCW). We aim to evaluate the effectiveness of the BBIBP-CorV vaccine to prevent SARS-CoV-2 infection and deaths among HCWs.

METHODS

Retrospective cohort study, from February 9 to June 30, 2021, using national registries of health care workers, laboratory tests for SARS-CoV-2 and deaths. We calculated the vaccine effectiveness for preventing laboratory-confirmed SARS-CoV-2 infection, COVID-19-mortality, and all-cause mortality among partially immunized and fully immunized HCWs. An extension of Cox proportional hazards regression was used to model the mortality results, and Poisson regression was used to model SARS-CoV-2 infection.

RESULTS

The study included 606,772 eligible HCWs, the mean age was 40 (IQR: 33.0, 51.0). In fully immunized HCW, the effectiveness for preventing all-cause mortality was 83.6 (95% CI: 80.2 to 86.4), 88.7 (95% CI: 85.1 to 91.4) for preventing COVID-19 mortality, and 40.3 (95% CI 38.9 to 41.6) for preventing SARS-CoV-2 infection.

CONCLUSION

The BBIBP-CorV vaccine showed high levels of effectiveness for preventing all-cause and COVID-19 deaths among fully immunized HCW. These results were consistent within different subgroups and sensitivity analyses. However, the effectiveness for preventing infection was suboptimal in this particular setting.

COVID-19 in Latin America: A Snapshot in Time and the Road Ahead

Since its initial detection in Brazil in February 2020, SARS-CoV-2 and the associated COVID-19 pandemic have continued to devastate Latin America. Specific comorbidities, as well as sociodemographic and lifestyle factors that may be more prevalent in underserved areas, have been identified as risk factors for COVID-19 infection or associated adverse outcomes. Dynamics of infections and deaths in Latin America have varied by country and temporally, as has SARS-CoV-2 variant prevalence; however, more recently, the Delta and subsequent Omicron variants have become ubiquitous. Successful pandemic responses have involved robust infection mitigation measures, testing, and smart deployment of healthcare resourcing. While in some Latin American countries up to 90% of the population is fully vaccinated (i.e., 2 doses) against COVID-19, other countries have failed to reach the World Health Organization's 70% target. Continued focus on comprehensive surveillance, strategies to maximize vaccine availability and uptake, and mitigation of collateral damage on other aspects of public health and social services are critical for managing the COVID-19 pandemic. This review summarizes the COVID-19 experience in Latin America, including epidemiology and vaccination. Key learnings and future considerations for the ongoing pandemic response are also discussed.

Achieving herd immunity in South America

South America, once an epicenter of COVID-19, has stayed on the road of continued management of the pandemic. The region initially struggled to cope with the pandemic as it experienced spiraling numbers of infections and overwhelmed public health systems. South America has risen in its pandemic response to be the region with the highest global vaccination rate. The region posed a strong vaccination drive, with over 76% of its population fully vaccinated with the initial protocol. South America leveraged its deeply rooted vaccination culture and public health confidence among its population. Herd immunity is an integral concept in population infectious disease management. Attaining herd immunity is presently not feasible with available vaccines, but the high vaccination rate in the region depicts the acceptance of vaccination as a strategy for population protection. The availability of effective transmission-blocking vaccines, the continuous implementation of strategies that will enable the undisrupted supply of the vaccines, equity in access to the vaccines, improved vaccine acceptance, and trust in the vaccination and public health systems will help shepherd the region towards herd immunity. Local vaccine production backed with investment in infrastructure and international collaboration for research and knowledge development will also drive population safety.

[Social determinants associated with self-reporting of symptoms and access to COVID-19 testing and diagnosis in the Plurinational State of BoliviaDeterminantes sociais associados ao autorrelato de sintomas, acesso a testagem e diagnóstico de COVID-19 no Estado Plurinacional da Bolívia]

Objective

To identify the prevalence of self-reporting of symptoms and access to testing and diagnosis of coronavirus-19 disease (COVID-19), as well as its association with social determinants of health (SDH).

Methods

Cross-sectional study with a sample of 11 728 men and 12 612 women over the age of 17, based on the National Household Survey 2020. The dependent variables were the self-reporting of symptoms, access to testing, and a positive COVID-19 test. The independent variables were age, educational level, area of residence and geographic area, ethnicity, type of household, income per capita, occupation, and health insurance. Prevalences, bivariate associations, and binomial logistical regression models (odds ratio (OR), and 95% confidence interval (CI95%) were calculated.

Results

Of the total individuals included, 16% reported symptoms, 10% a test, and 4.2% a positive COVID-19 test. Inequalities were observed in the reporting of COVID-19 symptoms, with a higher probability in women whose income had fallen (OR: 1.7; CI95%: 1.2-2.4) and unemployed persons (OR: 1.2; CI95%: 1.1-1.4 for men and OR: 1.3; CI95%: 1.5-1.5 for women). In contrast, with respect to access to diagnostic tests, the highest probability was observed in people with higher education (OR: 2.4; CI95%: 1.9-2.9 for men and OR: 2.7; CI95%: 2.2-3.4 for women), whose income was maintained (OR: 1.5; CI95%: 1.3-1.9 for men and OR: 1.7; CI95%: 1.4-2.0 for women) and those in the highest quartile of per capita household income (OR: 2.0; CI95%: 1.6-2.5 for men and OR: 1.6; CI95%: 1.3-2.0 for women). The probability of reporting symptoms and getting tested, and being diagnosed with COVID-19 increased with age for people with health insurance and those living in the llanos region; however, it decreased for residents of rural areas.

Conclusions

There are inequalities in access to testing and the reporting of COVID-19 symptoms.

Impact of SARS-CoV-2 vaccination in healthcare workers in a network of clinics in Latin America

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Frontline employees have been severely affected by COVID-19.

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This study assessed the effect of vaccination among healthcare staff in Colombia.

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COVID-19 infections in Colombia increased dramatically during early 2021.

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Vaccination rollout in frontline personnel reduced the incidence of new cases among healthcare workers, in contrast to the general population.

Objectives

Healthcare workers (HCWs) have been severely affected in terms of both morbidity and mortality since the beginning of the COVID-19 pandemic. During the first few months of 2021, Colombia experienced a surge in positive cases. This study aimed to evaluate the effect of vaccination on the incidence of new positive cases in HCWs.

Design

This was a retrospective cohort study of frontline employees in a network of clinics in Colombia, who were prioritized for COVID-19 vaccination from February to March 2021.

Results

Our findings were consistent with recent reports. During early 2020, the incidence of HCWs positively diagnosed with COVID-19 in Colombia was higher than that for the general population. With the start of the national vaccination program, the incidence among HCWs decreased from April 2021, while that for the general population remained relatively unchanged. Our study identified lower infection rates among HCWs during April (odds ratio [OR], 0.72 [95% CI 0.58–0.90]; p < 0.01) and May (odds ratio [OR], 0.25 [95% CI 0.18–0.36]; p < 0.01).

Conclusions

COVID-19 vaccination rollout in Colombia during early 2021 led to a decrease in the incidence of new positive cases among HCWs, in contrast to a continuing surge in the general population. Our findings suggested that COVID-19 vaccination provided adequate immunity, which guaranteed protection to HCWs.

COVID-19 Prevalence among Healthcare Workers. A Systematic Review and Meta-Analysis

Understanding the burden of SARS-CoV-2 infections among healthcare workers is a critical component to inform occupational health policy and strategy. We conducted a systematic review and meta-analysis to map and analayse the available global evidence on the prevalence of SARS-CoV-2 infections among healthcare workers. The random-effects adjusted pooled prevalence of COVID-19 among those studies that conducted the test using the antibody (Ab) method was 7% [95% CI: 3 to 17%]. The random-effects adjusted pooled prevalence of COVID-19 among those studies that conducted the test using the PCR method was 11% [95% CI: 7 to 16%]. We found the burden of COVID-19 among healthcare workers to be quite significant and therefore a cause for global health concern. Furthermore, COVID-19 infections among healthcare workers affect service delivery through workers’ sick leave, the isolation of confirmed cases and quarantine of contacts, all of which place significant strain on an already shrunken health workforce.

Prevalence and Factors Associated with Parents' Non-Intention to Vaccinate Their Children and Adolescents against COVID-19 in Latin America and the Caribbean

We aimed to estimate the prevalence and factors associated with parents' non-intention to vaccinate their children and adolescents against COVID-19 in Latin America and the Caribbean (LAC). We performed a secondary analysis using a database generated by the University of Maryland and Facebook (Facebook, Inc., Menlo Park, CA, USA). We included adult (18 and over) Facebook users residing in LAC who responded to the survey between 20 May 2021 and 14 July 2021. We included sociodemographic characteristics, comorbidities, mental health, economic and food insecurity, compliance with mitigation strategies against COVID-19, and practices related to vaccination against this disease. We estimated the crude (cPR) and adjusted (aPR) prevalence ratios with their respective 95%CI. We analyzed a sample of 227,740 adults from 20 LAC countries. The prevalence of parents' non-intention to vaccinate their children and adolescents against COVID-19 was 7.8% (n = 15,196). An age above 35 years old, educational level above college, compliance with physical distancing, use of masks, having economic insecurity, having had COVID-19, anxiety symptoms, depressive symptoms, having a chronic condition or two or more comorbidities, and being vaccinated were associated with a lower prevalence of non-intention to vaccinate children and adolescents against COVID-19. Living in a town, a village, or a rural area was associated with a higher prevalence of non-intention to vaccinate children and adolescents against COVID-19. Approximately nine out of ten parents in LAC intended to vaccinate their children and adolescents against COVID-19. Our results allow for understanding parents' intentions to vaccinate children and adolescents and help promote and develop education strategies for national vaccination plans against COVID-19.

Seroprevalence of anti-SARS-CoV-2 IgG at the first epidemic peak in French Guiana, July 2020

BACKGROUND

While Latin America has been heavily affected by the pandemic, only a few seroprevalence studies have been conducted there during the first epidemic wave in the first half of 2020.

METHODOLOGY/PRINCIPAL FINDINGS

A cross-sectional survey was performed between 15 July 2020 and 23 July 2020 among individuals who visited 4 medical laboratories or 5 health centers for routine screening or clinical management, with the exception of symptomatic suggestive cases of covid-19. Samples were screened for the presence of anti-SARS-CoV-2 IgG directed against domain S1 of the SARS-CoV-2 spike protein using the anti-SARS-CoV-2 enzyme-linked immunosorbent assay (ELISA) from Euroimmun.

CONCLUSIONS/SIGNIFICANCE

The overall seroprevalence was 15.4% [9.3%-24.4%] among 480 participants, ranging from 4.0% to 25.5% across the different municipalities. The seroprevalence did not differ according to gender (p = 0.19) or age (p = 0.51). Among SARS-CoV-2 positive individuals, we found that 24.6% [11.5%-45.2%] reported symptoms consistent with COVID-19. Our findings revealed high levels of infection across the territory but a low number of resulting deaths, which can be explained by French Guiana's young population structure.

Seroprevalence of SARS-CoV-2 antibodies in the general population of Oman: results from four successive nationwide sero-epidemiological surveys

OBJECTIVE

To assess the seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in Oman and longitudinal changes in antibody levels over time within the first 11 months of the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

This nationwide cross-sectional study was conducted as a four-cycle serosurvey using a multi-stage stratified sampling method from July to November 2020. A questionnaire was used and included demographics, history of acute respiratory infection and list of symptoms, COVID-19 contact, previous diagnosis or admission, travel history and risk factors.

RESULTS

In total, 17,457 participants were surveyed. Thirty percent were female and 66.3% were Omani. There was a significant increase in seroprevalence throughout the study cycles, from 5.5% (4.8-6.2%) in Cycle 1 to 22% (19.6-24.6%) in Cycle 4. There was no difference in seroprevalence between genders, but significant differences were found between age groups. There was a transition of seroprevalence from being higher in non-Omanis than Omanis in Cycle 1 [9.1% (7.6-10.9%) vs 3.2% (2.6-3.9%)] to being higher in Omanis than non-Omanis in Cycle 4 [24.3% (21.0-27.9%) vs 16.8% (14.9-18.9%)]. There was remarkable variation in the seroprevalence of SARS-CoV-2 according to governorate. Close contacts of people with COVID-19 had a 96% higher risk of having the disease [adjusted odds ratio (AOR) 1.96, 95% confidence intervals (CI) 1.64-2.34]. Labourers had 58% higher risk of infection compared with office workers (AOR 1.58, 95% CI 1.04-2.35).

CONCLUSION

This study showed a wide variation in the spread of SARS-CoV-2 across governorates in Oman, with higher estimated seroprevalence in migrants in the first two cycles. Prevalence estimates remain low and are insufficient to provide herd immunity.