to authorize a second booster shot of its vaccine — that is, a fourth dose — for people aged 65 and older. Two days later, Moderna followed suit, but with a broader request to authorize a second booster for all adults over 18. The agency said on Tuesday that adults aged 50 and older could opt for a second booster shot of the vaccines made by Pfizer-BioNTech or Moderna, to be given at least four months after the first booster of any authorized or approved Covid vaccine. A second booster would be the third shot for those who received one dose of the Johnson & Johnson vaccine and a booster shot of an mRNA vaccine. In fact, other data from Israel suggests that a second booster has only marginal benefits in healthy young people.

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