The Food and Drug Administration authorized booster doses for the Moderna and Johnson & Johnson COVID-19 vaccines, following its authorization of a third Pfizer / BioNTech shot in September. The agency also said today that it will allow “mix-and-match” boosters — eligible people who are already fully vaccinated can get a booster dose of any of the three vaccines, regardless of which they started with. As with the Pfizer / BioNTech booster, the FDA cleared third Moderna shots for vulnerable gr...