Three doses of a Covid-19 vaccine is the “optimal care” but two doses of the Pfizer/BioNTech or Moderna vaccines or one of the Johnson & Johnson vaccine remains the US government's official definition of fully vaccinated, top US infectious disease expert Anthony Fauci has said.

“For official requirements, it's still two shots of the mRNA (Pfizer/BioNTech or Moderna) and one shot of the J&J for the official determination of what's required or not. But I think if you look at the data, the more and more it becomes clear that if you want to be optimally protected you really should get a booster,” Reuters quoted Fauci as telling the ABC's “This Week With George Stephanopoulos.”