RESUMO
Over the past two years, the COVID-19 pandemic has seen multiple waves with high morbidity and mortality. Lockdowns and other prompt responses helped India's situation become less severe. Although Malegaon in the Indian state of Maharashtra has a high population density, poor hygienic standards, and oppositional local community views toward national pandemic addressing measures, it is nevertheless reasonably safe. To understand the possible reasons serosurvey was conducted to estimate the anti-SARS-CoV-2 neutralizing antibody levels in the Malegaon population. Also, we did SUTRA mathematical modeling to the Malegaon daily data on COVID-19 attributable events and compared it with the National and state level. The case fatality rate (CFR) in Malegaon city for the first, second, and third waves was 3.25%, 2.25%, and 0.39%, respectively. The crude death rate (CDR) for Maharashtra ranked first for the initial two waves and India for the third wave. Malegaon, meanwhile, finished second in the first two waves but fared best in the third. The Vaccination coverage for the first dose before the second wave was only 0.34% but had risen to 64.46% by 12 Oct 2022. By then, the second and booster dose coverage was 27.55% and 2.38%, respectively. Serosurvey did between 12 and 18 Jan 2022 showed a 93.93% anti-SARS-CoV-2 neutralizing antibody presence. SUTRA modeling elucidated the high levels of antibodies due to the pandemic-reach over 102% by the third wave. The serosurvey and the model explain why the pandemic severity in terms of duration and CFR during the subsequent waves, especially third wave, was milder compared to the first wave in spite of low vaccination rates. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01096-3.
RESUMO
BACKGROUND: Given the high incidence of asymptomatic or subclinical SARS-CoV-2 infection, reported cases likely underestimate the overall prevalence and infectivity of COVID-19. Serological test for IgG can provide a better measure of disease activity by identifying asymptomatic or subclinical infection. This study was conducted to estimate the seroprevalence of SARS-CoV-2 infection and to the determinants of SARS-CoV-2 infection in the hotspot area of COVID-19. METHOD: It was a community-based, cross-sectional study using multistage sampling with a sample size of 360. After informed consent, the demographic information, past history of SARI/ILI, contact, COVID-19 status were collected. The blood samples were taken from one family member for anti-SARS-CoV-2 IgG antibody by ELISA testing kit. RESULTS: Majority of the study subjects had no history of SARI (86%) or any contact with COVID-19 case (98%). Overall seroprevalence of anti-SARS-CoV-2 of IgG antibody was 40% (95% CI 35-45%), infection fatality rate (IFR) was 0.7%. Seroprevalence varied significantly depending on religious background; with Muslims (53%) seroprevalence compared to other religious groups. Seroprevalence of homemaker/unemployed (49%) and laborer (55%) was significantly higher compared to business (30%) and service occupation (21%). Subjects with overcrowding conditions and poor ventilation was significantly associated with higher seroprevalence with odds ratio of 2.5 and 2.3, respectively. CONCLUSION: The antibody testing detects a large number of asymptomatic cases or previously infected cases which would have been missed by clinical history. Thus, the number of undiagnosed cases was found significantly higher even with rigorous implementation of lockdown.
