Source: United States & Canada – South China Morning PostThe United States on Tuesday authorised a fourth dose of either the Pfizer-BioNTech or Moderna Covid-19 vaccines for people 50 and older, as authorities warn of a possible new wave driven by the BA.2 subvariant.The Food and Drug Administration (FDA) said in a statement it had based its decision on emerging evidence that an additional booster, given four months after the last, improved protection against severe Covid-19 and was not associated with new safety concerns.Additionally, people with…Read More