Population-Based Serosurvey for Severe Acute Respiratory Syndrome Coronavirus 2 Transmission, Chennai, India
Sriram Selvaraju, Muthusamy Santhosh Kumar, Jeromie Wesley Vivian Thangaraj, Tarun Bhatnagar, Saravanakumar Velusamy, C. P. Girish Kumar, Krithikaa Sekar, Ezhilarasan Ilayaperumal, R. Sabarinathan, M Jagadeesan, Masanam Sriramulu Hemalatha, Manoj Vasant Murhekar, the Chennai COVID Sero-Surveillance Team
Abstract
We conducted a household-based cross-sectional survey among usual residents >10 years of age in GCC. To estimate a seroprevalence of 2%, with 20% relative precision, design effect of 2.5, and 95% CI, we needed a sample size of 11,710 persons, which we rounded to 12,000. We used a multistage cluster sampling method to select the survey participants. In the first stage, we selected 51 wards by using probability proportion to population size method. In the second stage, we randomly selected 6 streets from each ward from which to recruit participants. The survey team selected a random starting point in each street and visited contiguous households to enroll >40 consenting persons >10 years of age. When no one was home or household members were unavailable, the team proceeded to the next house and completed the survey until >40 persons were enrolled from each street. We included all eligible persons in the household who consented.