One reason Pfizer and Moderna may have had trouble with their COVID-19 vaccine trials for the under-5 crowd is that the under-5 crowd already has such robust immunity that the vaccines might not have much of an effect on the children’s immune systems. A drug with a negligible effect is not going to get approved.

How safe are young children? A grand total of 2,203 children under 5 have been hospitalized with COVID-19 in the course of the pandemic. That number, according to hospital officials, is mostly children hospitalized for something else who incidentally test positive for COVID-19. Some of those are children who tested positive and then a week later broke an arm.

If those hospital officials are correct about “most” pediatric COVID-19 hospitalizations being caused by something else, then the coronavirus has sent less than 1,100 children under 5 to the hospital. That’s out of about 2 million children under the age of 5. That’s less than 1 in 1,000, and it’s probably far, far less considering the expansive definition of “COVID hospitalizations.”