Pfizer has asked the FDA for an emergency use authorization to administer its vaccine to children aged 5 to 11 based primarily on a study that enrolled 2,268 children. This sample size is severely underpowered to determine if the vaccine will save more children than it kills because less than one out of every 250,000 children in the U.S. aged 5 to 14 have died from Covid-19 since the start of the pandemic. Also, the Pfizer study is not a randomized controlled trial, which is the "gold standard" for clinical research because they provide "a rigorous tool to examine cause-effect," which "is not possible with any other study design."