News ‘Our best defense’: Pfizer says third dose of its COVID vaccine protects against omicron December 8, 2021Karen Weintraub, USA TODAYComments Off on ‘Our best defense’: Pfizer says third dose of its COVID vaccine protects against omicron A third dose of the Pfizer-BioNTech vaccine appears to be as effective against omicron as two doses were against the original variant.