Novel Coronavirus or SARS-CoV-2 has infected over 1.08 crore people in India but according to a latest sero survey conducted by the Indian Council of Medical Research (ICMR), around 29 crore people in the country have been infected with COVID-19. Why is there this huge difference in the confirmed COVID-19 cases and the sero prevalence? According to experts, the COVID-19 cases can be asymptomatic or there are chances that people didn't report of the infection. This is exactly where the role of sero survey comes in, to gauge the prevalence of the virus in a particular area. Here is everything you need to know about sero surveys.