Pfizer requests authorization for second booster

Drugmaker Pfizer is expected to request authorization this week for an additional COVID-19 booster dose for seniors. That would add a fourth dose to the regimen, which currently consists of a primary series of two shots, followed months later by a booster dose, in an effort to provide maximum protection to the over-65 population that has been hit hardest by the pandemic. The US Food and Drug Administration and the Centers for Disease Control must approve the request.