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. 2022 Mar:116:138-146.
doi: 10.1016/j.ijid.2021.12.356. Epub 2021 Dec 28.

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

Divya Dayanand  1 , Indhuja Irudhayanathan  1 , Debasree Kundu  1 , Abi Manesh  1 , Vinod Abraham  2 , Kundavaram Pp Abhilash  3 , Binila Chacko  4 , Mahesh Moorthy  5 , Prasanna Samuel  6 , Pimnara Peerawaranun  7 , Mavuto Mukaka  8 , Jayaraj Joseph  9 , Mohanasankar Sivaprakasam  9 , George M Varghese  10
Affiliations

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

Divya Dayanand et al. Int J Infect Dis. 2022 Mar.

Abstract

Objectives: The aim of this study was to inform public health policy decisions through the assessment of IgG antibody seroprevalence in the population and the risk factors for SARS-CoV-2 infection.

Methods: The seroprevalence of IgG antibodies among different subpopulations at the end of the first and second waves of the pandemic was estimated. Various risk factors associated with seropositivity, including sociodemography, IgG antibodies against endemic human coronavirus, and vaccination status, were also assessed.

Results: For all 2433 consenting participants, the overall estimated seroprevalences at the end of first and second waves were 28.5% (95% CI 22.3-33.7%) and 71.5% (95% CI 62.8-80.5%), respectively. The accrual of IgG positivity was heterogeneous, with the highest seroprevalences found in urban slum populations (75.1%). Vaccine uptake varied among the subpopulations, with low rates (< 10%) among rural and urban slum residents. The majority of seropositive individuals (75%) were asymptomatic. Residence in urban slums (OR 2.02, 95% CI 1.57-2.6; p < 0.001), middle socioeconomic status (OR 1.77, 95% CI 1.17-2.67; p = 0.007), presence of diabetes (OR 1.721, 95% CI 1.148-2.581; p = 0.009), and hypertension (OR 1.75, 95% CI 1.16-2.64; p = 0.008) were associated with seropositivity in multivariable analyses.

Conclusion: Although considerable population immunity has been reached, with more than two-thirds seropositive, improved vaccination strategies among unreached subpopulations and high-risk individuals are suggested for better preparedness in future.

Keywords: COVID; India; SARS-CoV-2; Seroprevalence.

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Conflict of interest statement

Declaration of Competing Interest The authors have no conflicts of interest to declare.

Figures

Figure 1
Figure 1
COVID-19 peaks in India during wave 1 and wave 2, with two sampling periods (modified from Covid19India.org, 2021). The x-axis represents the timeline in months and the y-axis gives the number of infected cases in lakhs. The study samples at the end of wave 1 were collected in January 2021, and those at the end of wave 2 were collected in July 2021.
Figure 2
Figure 2
Visual representation of community seroprevalence, with 95% confidence intervals, in various subpopulations at the end of wave 1 and wave 2. The x-axis represents IgG seropositivity as a percentage, and the y-axis shows the various subpopulations.
Figure 3
Figure 3
Seropositivity and vaccination status (participants who received one dose and those fully vaccinated) in the total study population and the various subpopulations. The rural areas and urban slums had the lowest vaccination levels — of 10.4% and 6.6%, respectively. Healthcare workers had the highest vaccination rate of 91.6%, followed by the urban affluent subpopulation, with a rate of 65.7%.
See this image and copyright information in PMC

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