On Friday, Pfizer and BioNTech said that their vaccine had proved more than 90 percent efficacy in children between ages 5 and 11. However, the companies acknowledged the possibility of post-vaccination myocarditis among children, in the report.

"While benefits of vaccination were highly dependent on Covid-19 incidence, the overall analysis predicted that the numbers of clinically significant Covid-19-related outcomes prevented would clearly outweigh the numbers of vaccine-associated excess myocarditis cases over a range of assumptions for Covid-19 incidence," the FDA's report read.

Next week, FDA experts are set to hold a meeting on the recommendation to allow emergency use of the vaccine for children aged 5-11, with the approval for emergency use is expected in November.

At the moment, emergency use of the Pfizer vaccine is authorized for those older than 12, and fully sanctioned for people aged 16 and over. Since the beginning of the pandemic, at least 1.8 million children between ages 5 and 11 have contracted Covid-19 in the US, and at least 143 children succumbed to the disease.