effective in protecting kids ages 5 to 11. clinical trials showed an efficacy rate of 90%, that's pretty good. an fda panel will consider pfizer's request for approval for that age group next week. as of today, booster shots are available to millions more americans. the cdc officially green lit the moderna and johnson & johnson shots yesterday along with mixing and matching of boosters. here is what the director of the cdc said earlier on "today." >> the vast majority of people will probably select the one that they originally received and did really well with. but there may be some people who would prefer a different vaccine or if you go into a pharmacy and they don't have the vaccine that you originally got, it really is fine to get a different vaccine. >> and nbc news correspondent miguel almaguer has more. >> reporter: yasmin, with the cdc's director's signoff overnight, those booster shots can start going into arms immediately. well over 30 million americans now qualify for a booster shot of moderna or johnson & johnson.