Background: There were limited data on the true burden of COVID 19 infection in children since the majority of the infections are asymptomatic or paucisymptomatic. This study aimed to measure the prevalence of SARS CoV2 antibodies in children of the 5-to-18 years age group. Methods: A community-based cross-sectional study was conducted in the field practice area attached to a tertiary care hospital in Kerala. Two hundred four children of the 5-to-18 year age group were enrolled in our study. The data regarding sociodemographic details, symptoms suggestive of COVID 19, exposure to confirmed COVID 19 cases and history of COVID 19 positivity were collected from the study participants. 2 ml venous blood was collected from each participant, and the seroprevalence of SARS CoV2 combined antibodies was assessed using WANTAI antibody test kit. Results: The seroprevalence of SARS Cov2 antibodies in children of 5-to-18 years age group was 41.7% (95% CI,34.9% to 48.43%). The seroprevalence was high in the 13-to-15 year age group, almost similar in both gender and socio-economic groups. The seropositivity was significantly associated with history of confirmed COVID 19 positivity, children with a history of symptoms suggestive of COVID 19 and the presence of positive contact in the household ( P < 0.05). Seroprevalence was also significantly high in children whose mothers were health care workers. Conclusion: Approximately 41.7% of children showed seropositivity to COVID 19 infection. More than 50% of the children remain susceptible. Among seropositive, 56.5% were asymptomatic. Thus there is a need to test even asymptomatic children in COVID 19 positive households.