Question on Vaccines

Why don't the Democrats direct their ire at the plodding pace of FDA approval for young kid vaccinations? The national association of pediatricians wrote a strongly worded letter to the FDA to basically let kids over age 5 get vaccinated already. What is the hold up? How are we doing this again? 

Am I the only one that sees no basic public health policy improvements between the Biden Admin and Trump? The only successful element of public health policy during COVID was the creation of the vaccine. Would mask policy have helped much? I'm not really sure.