Approval of Pfizer vaccinations against the Wuhan Virus for kids under 5 years old has been delayed as Pfizer has opted to test more before looking for approval. The vaccines don’t seem to work as well as hoped against the Omicron variant. But this part of the reasoning in the linked article jumped out at me.

So few study subjects [those kids], whether vaccinated or unvaccinated, developed Covid-19 during testing thus far that the small number of Omicron cases made the vaccine appear less effective in an early statistical analysis, the people said.

There’s a hint there both about the kids’ baseline susceptibility and about the virus situation at large.