Supplementary Table 1.

Districts for the serosurvey by strata based on incidence of reported COVID-19 cases

Stratum	District selected in the stratum
Zero	Vizianagaram, Pakur, Beed, Ganjam, Bijapur, Balrampur, Kabeerdham, Gonda, Karbi, Anglong, Udalguri, Kullu, Latehar, Chitradurga, Rayagada, Alipurduar
Low	Alipurduar, Parbhani, Nanded, Madhubani, Simdega, Koraput, Purnia, Rajsamand, Bareilly, Jangoan, Begusarai, Jalor Garhwal, Kurukshetra, Kamareddy, Unnao, Mau, Kamrup Metropolitan, Muzaffarpur, Sabar, Kantha, Gurdaspur, Bankura, Jhargram
Medium	24 Paraganas South, Pulwama, Tiruvannamalai, Sangli, Ahmad Nagar, Arwal, Thrisur, Gwalior, Auraiya, Jalgaon, Ernakulam, Nalgonda, Ludhiana, Surguja, Palakkad, Medinipur East
High	Coimbatore, Chennai, Buxar, Ujjain, Dausa, Gautam Buddha Nagar, Patiala, Krishna, Sri Potti Sriramulu Nellore, Jalandhar, Saharanpur, Jyotiba Phule Nagar, Narmada, Mahisagar, Bangalore, Gulbarga, Dewas