Some comorbidities are risk factors for severe coronavirus disease (Covid-19) but it is unknown whether some increase susceptibility to Covid-19 in children. In this Mexican case-control study, contact with patients with Covid-19, or having obesity, or having diabetes, or hypertension or been immunosuppressed independently increased the risk for Covid-19 in the whole sample analysis. However, only contact history and obesity remained statistically significant in the separated analysis of girls and boys. The results suggest that obesity is not only associated with severe disease but also increases risk for Covid-19. Contrary to findings in adults, no difference between cases and controls was found for gender, presence of pneumonia or surrogates of severe disease including admission to intensive care unit, tracheal intubation or whether patient had died. This indicates that Covid-19 is less severe in children than adults. Future research is needed to establish the mechanisms involved in obesity and Covid-19 in children. © 2020 World Obesity Federation.