Prevalence of SARS-CoV-2 infection in India: Findings from the national serosurvey, May-June 2020

• Main Authors: Manoj V Murhekar, Tarun Bhatnagar, Sriram Selvaraju, Kiran Rade, V Saravanakumar, Jeromie Wesley Vivian Thangaraj, Muthusamy Santhosh Kumar, Naman Shah, R Sabarinathan, Alka Turuk, Parveen Kumar Anand, Smita Asthana, Rakesh Balachandar, Sampada Dipak Bangar, Avi Kumar Bansal, Jyothi Bhat, Debjit Chakraborty, Chethana Rangaraju, Vishal Chopra, Dasarathi Das, Alok Kumar Deb, Kangjam Rekha Devi, Gaurav Raj Dwivedi, S Muhammad Salim Khan, Inaamul Haq, M Sunil Kumar, Avula Laxmaiah, Madhuka, Amarendra Mahapatra, Anindya Mitra, A R Nirmala, Avinash Pagdhune, Mariya Amin Qurieshi, Tekumalla Ramarao, Seema Sahay, Y K Sharma, Marinaik Basavegowdanadoddi Shrinivasa, Vijay Kumar Shukla, Prashant Kumar Singh, Ankit Viramgami, Vimith Cheruvathoor Wilson, Rajiv Yadav, C P Girish Kumar, Hanna Elizabeth Luke, Uma Devi Ranganathan, Subash Babu, Krithikaa Sekar, Pragya D Yadav, Gajanan N Sapkal, Aparup Das, Pradeep Das, Shanta Dutta, Rajkumar Hemalatha, Ashwani Kumar, Kanwar Narain, Somashekar Narasimhaiah, Samiran Panda, Sanghamitra Pati, Shripad Patil, Kamalesh Sarkar, Shalini Singh, Rajni Kant, Srikanth Tripathy, G S Toteja, Giridhara R Babu, Shashi Kant, J P Muliyil, Ravindra Mohan Pandey, Swarup Sarkar, Sujeet K Singh, Sanjay Zodpey, Raman R Gangakhedkar, D C S. Reddy, Balram Bhargava
• Format: Article
• Language: English
• Published: Wolters Kluwer Medknow Publications 2020-01-01
• Series: Indian Journal of Medical Research
• Subjects: antibody - covid-19 - elisa - igg - india - sars-cov-2 - seroepidemiology - seroprevalence - serosurveillance
• Online Access: http://www.ijmr.org.in/article.asp?issn=0971-5916;year=2020;volume=152;issue=1;spage=48;epage=60;aulast=Murhekar

Background & objectives: Population-based seroepidemiological studies measure the extent of SARS-CoV-2 infection in a country. We report the findings of the first round of a national serosurvey, conducted to estimate the seroprevalence of SARS-CoV-2 infection among adult population of India. Methods: From May 11 to June 4, 2020, a randomly sampled, community-based survey was conducted in 700 villages/wards, selected from the 70 districts of the 21 States of India, categorized into four strata based on the incidence of reported COVID-19 cases. Four hundred adults per district were enrolled from 10 clusters with one adult per household. Serum samples were tested for IgG antibodies using COVID Kavach ELISA kit. All positive serum samples were re-tested using Euroimmun SARS-CoV-2 ELISA. Adjusting for survey design and serial test performance, weighted seroprevalence, number of infections, infection to case ratio (ICR) and infection fatality ratio (IFR) were calculated. Logistic regression was used to determine the factors associated with IgG positivity. Results: Total of 30,283 households were visited and 28,000 individuals were enrolled. Population-weighted seroprevalence after adjusting for test performance was 0.73 per cent [95% confidence interval (CI): 0.34-1.13]. Males, living in urban slums and occupation with high risk of exposure to potentially infected persons were associated with seropositivity. A cumulative 6,468,388 adult infections (95% CI: 3,829,029-11,199,423) were estimated in India by the early May. The overall ICR was between 81.6 (95% CI: 48.3-141.4) and 130.1 (95% CI: 77.0-225.2) with May 11 and May 3, 2020 as plausible reference points for reported cases. The IFR in the surveyed districts from high stratum, where death reporting was more robust, was 11.72 (95% CI: 7.21-19.19) to 15.04 (9.26-24.62) per 10,000 adults, using May 24 and June 1, 2020 as plausible reference points for reported deaths. Interpretation & conclusions: Seroprevalence of SARS-CoV-2 was low among the adult population in India around the beginning of May 2020. Further national and local serosurveys are recommended to better inform the public health strategy for containment and mitigation of the epidemic in various parts of the country.