The corona virus named COVID-19 was observed to affect people differently according to their blood type. Early suggestions noted that the gene that determines blood type is located near to genes important for immune reaction, but no explanation of the association was immediately available. The data report counts of COVID-19 patients from a hospital in Wuhan, China, categorized by blood type (A, B, AB, O) and age. Similar observations have been published from European sites as well, but the work from which these data are taken had not been refereed at that time.