Community seroprevalence and risk factors for SARS CoV-2 infection in different subpopulations in Vellore, India and its implications for future prevention

Sero-Surveillance to Evaluate Trends in the Transmission of SARS-CoV-2 in a Central Indian District

Background and objective The actual community burden of SARS-CoV-2 is undervalued, as the estimates are just the symptomatic infections. The acute phase of the pandemic has waned, and the analytical comparison of infection spread through repeated sero-epidemiological studies is important in the formulation of effective public health strategies. This study investigated the level of seroprevalence of IgG antibodies for the SARS-CoV-2 virus in the Nagpur district, Maharashtra, India. Materials and methods The present cross-sectional survey was conducted over three months from September to November 2021 by carrying out a door-to-door survey involving 6129 participants. Among them, 3131 were from municipal areas, while the rest were from non-municipal regions. Data collection was facilitated using Google Forms (Google LLC, Mountain View, California, United States). Venous blood samples were collected, and SARS-CoV-2 antibodies were detected using the COVID KAVACH IgG enzyme-linked immunosorbent assay (ELISA) kit (developed by the National Institute of Virology (NIV), Pune, India). The information collected was then cleaned, coded, and analyzed using Epi Info software (Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA). Results The seroprevalence rate was found to be 80% in the whole district. Females had a higher seroprevalence rate in both areas than males. The population aged 60 years and above had the highest seroprevalence rate in both zones. The vaccinated group demonstrated a greater number of individuals testing positive for SARS-CoV-2 compared to the unvaccinated group. Conclusion The significant increase in the seroprevalence estimates in relation to the prior survey is because of the significant surge in COVID-19 vaccination coverage after the first wave of the pandemic. The findings of the study imply the dynamic nature of the pandemic and the different degrees of immunity obtained within the community. Ongoing surveillance and research are essential for refining effective strategies to manage and mitigate future pandemics effectively.

Tracking Immunity: An Increased Number of COVID-19 Boosters Increases the Longevity of Anti-RBD and Anti-RBD-Neutralizing Antibodies

BACKGROUND/OBJECTIVES

Since the World Health Organization declared COVID-19 a pandemic in March 2020, the virus has caused multiple waves of infection globally. Arizona State University (ASU), the largest four-year university in the United States, offers a uniquely diverse setting for assessing immunity within a large community. This study aimed to test our hypothesis that an increased number of exposures to SARS-CoV-2 RBD through vaccination/boosters/infection will increase SARS-CoV-2 antibody seroprevalence by increasing the longevity of anti-RBD and anti-RBD-neutralizing antibodies.

METHODS

A serosurvey was conducted at ASU from 30 January to 3 February 2023. Participants completed questionnaires about demographics, respiratory infection history, symptoms, and COVID-19 vaccination status. Blood samples were analyzed for anti-receptor binding domain (RBD) IgG and anti-nucleocapsid (NC) antibodies, offering a comprehensive view of immunity from both natural infection and vaccination.

RESULTS

The seroprevalence of anti-RBD IgG antibodies was 96.2% (95% CI: 94.8-97.2%), and 64.9% (95% CI: 61.9-67.8%) of participants had anti-NC antibodies. Anti-RBD IgG levels correlated strongly with neutralizing antibody levels, and participants who received more vaccine doses showed higher levels of both anti-RBD IgG and neutralizing antibodies. Increasing the number of exposures through vaccination and/or infection resulted in higher and long-lasting antibodies.

CONCLUSIONS

The high levels of anti-RBD antibodies observed reflect substantial vaccine uptake within this population. Ongoing vaccination efforts, especially as new variants emerge, are essential to maintaining protective antibody levels. These findings underscore the importance of sustained public health initiatives to support broad-based immunity and protection.

Perceptions and compliance with COVID-19 preventive measures in Southern and Central regions of Mozambique: A quantitative in-person household survey in the districts of Manhiça and Quelimane

The COVID-19 pandemic has prompted countries to swiftly implement rigorous preventive measures on a population-wide scale worldwide. However, in low-income countries like Mozambique this was difficult, coupled with a generalised lack of knowledge on how the population understood and complied with these measures. This study assessed community perceptions and implementation of anti-COVID-19 measures recommended by Mozambican authorities in Manhiça and Quelimane districts, including confinement, social distancing, frequent handwashing, mask wearing, and quarantine as the key practices to evaluate. We conducted a cross-sectional quantitative survey in October 2020 and February 2021, interviewing heads of households, face-to-face. The data collected included self-evaluation of compliance and existence of handwashing facilities and face-masks in the households, aided by observations. We present descriptive statistics on perceptions and compliance at individual and household levels. Out of the 770 participants, nearly all (98.7%) were aware of Coronavirus disease, including the term COVID-19 (89.2%). Knowledge varied between districts, with Manhiça participants showing higher levels of sufficient ability to define the disease. The symptoms most mentioned were dry cough (17.8%), fever (15.7%), flu-like symptoms (14.2%), breathing difficulties (13.6%), and headache (13.1%). Participants recognized various transmission modes, including touching infected objects and inhaling infected air. Preventive measures like handwashing with soap or sanitizing hands with alcohol, wearing masks, and social distancing were acknowledged, but the understanding varied. Compliance with these measures was generally low, with fewer than half of respondents reporting adherence to them. Only 30.4% of households had handwashing facilities (of which only 41.0% had water), and masks were often limited to one per person aged 6 years or more. Community members in Manhica and Quelimane were aware of COVID-19 but had limited understanding of what the preventive measures meant, and had lower levels of compliance. Understanding and addressing the factors affecting the proper implementation of these measures is crucial for improving community adherence in preventing infectious diseases with epidemic potential.

Contribution of infection and vaccination to population-level seroprevalence through two COVID waves in Tamil Nadu, India

This study employs repeated, large panels of serological surveys to document rapid and substantial waning of SARS-CoV-2 antibodies at the population level and to calculate the extent to which infection and vaccination separately contribute to seroprevalence estimates. Four rounds of serological surveys were conducted, spanning two COVID waves (October 2020 and April-May 2021), in Tamil Nadu (population 72 million) state in India. Each round included representative populations in each district of the state, totaling ≥ 20,000 persons per round. State-level seroprevalence was 31.5% in round 1 (October-November 2020), after India's first COVID wave. Seroprevalence fell to 22.9% in round 2 (April 2021), a roughly one-third decline in 6 months, consistent with dramatic waning of SARS-Cov-2 antibodies from natural infection. Seroprevalence rose to 67.1% by round 3 (June-July 2021), with infections from the Delta-variant induced second COVID wave accounting for 74% of the increase. Seroprevalence rose to 93.1% by round 4 (December 2021-January 2022), with vaccinations accounting for 63% of the increase. Antibodies also appear to wane after vaccination. Seroprevalence in urban areas was higher than in rural areas, but the gap shrunk over time (35.7 v. 25.7% in round 1, 89.8% v. 91.4% in round 4) as the epidemic spread even in low-density rural areas.

Assessment of immunoglobin G (spike and nucleocapsid protein) response to COVID-19 vaccination in Palestine

INTRODUCTION

Many countries have begun immunization programs and established protocols to combat pandemics caused by the SARS-CoV-2 virus. Six months after vaccination, the antibody titers produced by the immunization begin to decline, and individuals whose first immunization (either one or two doses) did not provide adequate protection may require a booster dose.

METHODS

A quantitative cross-sectional survey of 18-year-olds and older was undertaken in the West Bank from June 15 to June 27, 2022. Each participant had 5 mL of blood drawn to be tested for IgG-S, IgG-N, and blood group.

RESULTS

All participants had positive IgG-S results; IgG-S values ranged between 77 and 40,000 AU/ml, with a mean value of 1254 AU/ml. The value of IgG-N ranged from 0 to 139.3 U/ml for all participants, with a mean value of 22.4 U/ml. 64 (37.2%) of the participants demonstrated positive IgG-N screening results, with mean values of 51.2 U/ml. Female participants' mean IgG concentration was higher than male participants. Furthermore, the results revealed that smokers had lower levels of vaccine-induced antibodies than nonsmokers. High significance was found in the time from the last vaccine till the blood sample test (T = 3.848, P < .001), and the group between 6 and 9 months was found to have higher mean values than the 9-months group (M = 15952).

CONCLUSIONS

Participants vaccinated with a higher number of vaccines tend to have higher IgG-S. To elevate total antibodies, booster doses are essential. Additional researchers are needed to examine the positive correlation between IgG-S and IgG-N.