Pfizer's coronavirus vaccine should be safe for most Americans, but 4 groups have to wait for more data before getting shots

Margaret Keenan, the first person to be given the Pfizer coronavirus vaccine outside clinical trials.
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A recent FDA review found there was "insufficient data" to conclude whether Pfizer's coronavirus vaccine is safe for kids under 16, pregnant women, and immunocompromised people.
Experts also worry about vaccinating people who previously got COVID-19, particularly if these people have lingering symptoms.
Some of these vulnerable groups were included in Pfizer's late-stage clinical trials,