WASHINGTON, United States (AFP) — People who received Johnson & Johnson’s Covid-19 vaccine may benefit from a booster dose of Pfizer or Moderna, preliminary results of a US study published Wednesday showed. The study, funded by the National Institutes of Health (NIH), was eagerly awaited in the United States because it looked at the possibility of “mixing” vaccines — using a different vaccine than the initial doses for the booster shot — which is not […]