Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

ObjectivesThe 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.MethodsThe 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.ResultsFor 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.ConclusionAlthough 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.

Original publication




Journal article


International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases

Publication Date





138 - 146


Department of Infectious Diseases, Christian Medical College, Vellore, Tamil Nadu, India.


Humans, Antibodies, Viral, Risk Factors, Seroepidemiologic Studies, India, COVID-19, SARS-CoV-2