A previous interim analysis concluded that the incidence of selected serious outcomes was not significantly higher one to 21 days post-vaccination compared with 22-42 days post-vaccination for mRNA Covid-19 vaccines. Moreover, a further analysis indicated a low incidence of myocarditis and pericarditis among individuals persons aged five to 39 years. While these data are reassuring, further safety monitoring data are needed for mRNA doses, particularly when administered to children aged six months to five years of age, hence the current study.
