STAT
The FDA on Thursday authorized the administration of an additional dose of one of the messenger RNA Covid-19 vaccines for people who have certain immunocompromising conditions amid growing evidence that they do not get adequate protection from the normal two-dose regimen of the Pfizer-BioNTech or Moderna vaccines. … It does not apply to the one-dose Johnson and Johnson vaccine, which has been used far less in this country than the mRNA products.