Assessing the burden of COVID-19 on the basis of medically attended case numbers is sub optimal given its reliance on testing strategy, changing case definitions, and disease presentation. Population-based serosurveys measuring anti-SARS-CoV-2 antibodies provide one method for estimating infection rates and monitoring the progression of the epidemic.Sero-prevalance, or sero-surveys, would help understand the proportion of population exposed to SAR-CoV-2 infection including symptomatic.Depending on the level of sero-prevalence of the infection, appropriate public health interventions can be planned and implemented for prevention and control of the disease.Periodic sero-surveys are useful to guide the policy makers. For instance, a survey in high risk or vulnerable populations such as healthcare worker, front line workers, immune-compromised individuals, individuals in containment zones, etc. would show who has been infected in the past and if they have now recovered.Sero surveys are important when the containment strategy has failed and the only way forward remains the Herd Immunity.Recent results highlight that the vast majority of the population is still immunologically naive to this new virus. serological studies are crucial for providing new insights about transmission and the otherwise hidden immunological state of the population.