FDA greenlights Moderna boosters, mix-and-match shots

The U.S. Food and Drug Administration has given the O.K. to Covid-19 vaccine "booster" shots made by Cambridge biotech Moderna Inc. Moderna (Nasdaq: MRNA) is now able to make and distribute boosters — third shots identical to each of the first two in the series, but half the amount — for patients 65 and older, adults with underlying medical conditions and adults who are at a high risk for Covid-19 because of their occupations or time in institutional settings. The decision comes a few days…