Pfizer-BioNTech's COVID-19 vaccine won't be available anytime soon for kids younger than 5. In early tests, the lower dose given to 2- to 5-year-olds didn't produce as much immune protection as did shots given to other age groups … The company hopes a third dose of vaccine eight weeks after the first two shots will provide the desired effectiveness ... But that means waiting until late March or early April for results …