Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Dec 10;18(12):e1003877.
doi: 10.1371/journal.pmed.1003877. eCollection 2021 Dec.

Seroprevalence of IgG antibodies against SARS-CoV-2 among the general population and healthcare workers in India, June-July 2021: A population-based cross-sectional study

Manoj V Murhekar  1 , Tarun Bhatnagar  1 , Jeromie Wesley Vivian Thangaraj  1 , V Saravanakumar  1 , Muthusamy Santhosh Kumar  1 , Sriram Selvaraju  2 , Kiran Rade  3 , C P Girish Kumar  1 , R Sabarinathan  1 , Smita Asthana  4 , Rakesh Balachandar  5 , Sampada Dipak Bangar  6 , Avi Kumar Bansal  7 , Jyothi Bhat  8 , Debjit Chakraborty  9 , Vishal Chopra  10 , Dasarathi Das  11 , Kangjam Rekha Devi  12 , Gaurav Raj Dwivedi  13 , Agam Jain  14 , S Muhammad Salim Khan  15 , M Sunil Kumar  16 , Avula Laxmaiah  17 , Major Madhukar  18 , Amarendra Mahapatra  11 , Talluri Ramesh  19 , Chethana Rangaraju  20 , Jyotirmayee Turuk  11 , Suresh Yadav  21 , Balram Bhargava  22 ; ICMR serosurveillance group
Collaborators, Affiliations

Seroprevalence of IgG antibodies against SARS-CoV-2 among the general population and healthcare workers in India, June-July 2021: A population-based cross-sectional study

Manoj V Murhekar et al. PLoS Med. .

Abstract

Background: India began COVID-19 vaccination in January 2021, initially targeting healthcare and frontline workers. The vaccination strategy was expanded in a phased manner and currently covers all individuals aged 18 years and above. India experienced a severe second wave of COVID-19 during March-June 2021. We conducted a fourth nationwide serosurvey to estimate prevalence of SARS-CoV-2 antibodies in the general population aged ≥6 years and healthcare workers (HCWs).

Methods and findings: We did a cross-sectional study between 14 June and 6 July 2021 in the same 70 districts across 20 states and 1 union territory where 3 previous rounds of serosurveys were conducted. From each district, 10 clusters (villages in rural areas and wards in urban areas) were selected by the probability proportional to population size method. From each district, a minimum of 400 individuals aged ≥6 years from the general population (40 individuals from each cluster) and 100 HCWs from the district public health facilities were included. The serum samples were tested for the presence of IgG antibodies against S1-RBD and nucleocapsid protein of SARS-CoV-2 using chemiluminescence immunoassay. We estimated the weighted and test-adjusted seroprevalence of IgG antibodies against SARS-CoV-2, along with 95% CIs, based on the presence of antibodies to S1-RBD and/or nucleocapsid protein. Of the 28,975 individuals who participated in the survey, 2,892 (10%) were aged 6-9 years, 5,798 (20%) were aged 10-17 years, and 20,285 (70%) were aged ≥18 years; 15,160 (52.3%) participants were female, and 21,794 (75.2%) resided in rural areas. The weighted and test-adjusted prevalence of IgG antibodies against S1-RBD and/or nucleocapsid protein among the general population aged ≥6 years was 67.6% (95% CI 66.4% to 68.7%). Seroprevalence increased with age (p < 0.001) and was not different in rural and urban areas (p = 0.822). Compared to unvaccinated adults (62.3%, 95% CI 60.9% to 63.7%), seroprevalence was significantly higher among individuals who had received 1 vaccine dose (81.0%, 95% CI 79.6% to 82.3%, p < 0.001) and 2 vaccine doses (89.8%, 95% CI 88.4% to 91.1%, p < 0.001). The seroprevalence of IgG antibodies among 7,252 HCWs was 85.2% (95% CI 83.5% to 86.7%). Important limitations of the study include the survey design, which was aimed to estimate seroprevalence at the national level and not at a sub-national level, and the non-participation of 19% of eligible individuals in the survey.

Conclusions: Nearly two-thirds of individuals aged ≥6 years from the general population and 85% of HCWs had antibodies against SARS-CoV-2 by June-July 2021 in India. As one-third of the population is still seronegative, it is necessary to accelerate the coverage of COVID-19 vaccination among adults and continue adherence to non-pharmaceutical interventions.

PubMed Disclaimer

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Flowchart of participant enrolment.
See this image and copyright information in PMC

References

    1. World Health Organization. WHO coronavirus (COVID-19) dashboard. Geneva: World Health Organization; 2021. [cited 2021 Jul 28]. Available from: https://covid19.who.int/table.
    1. Government of India. #IndiaFightsCorona COVID-19. New Delhi: Government of India; 2021 [cited 2021 Dec 8]. Available from: https://www.mygov.in/covid-19.
    1. World Health Organization. Population-based age-stratified seroepidemiological investigation protocol for coronavirus 2019 (COVID-19) infection, 26 May 2020, version 2.0. Geneva: World Health Organization; 2020. [cited 2021 Dec 8]. Available from: https://apps.who.int/iris/handle/10665/332188.
    1. Murhekar MV, Bhatnagar T, Selvaraju S, Rade K, Saravanakumar V, Vivian Thangaraj JW, et al.. Prevalence of SARS-CoV-2 infection in India: findings from the national serosurvey, May–June 2020. Indian J Med Res. 2020;152:48–60. doi: 10.4103/ijmr.IJMR_3290_20 - DOI - PMC - PubMed
    1. Murhekar MV, Bhatnagar T, Selvaraju S, Saravanakumar V, Thangaraj JWV, Shah N, et al.. SARS-CoV-2 antibody seroprevalence in India, August–September, 2020: findings from the second nationwide household serosurvey. Lancet Glob Health. 2021;9:e257–66. doi: 10.1016/S2214-109X(20)30544-1 - DOI - PMC - PubMed

Publication types

Substances