[Press release – not published yet] Lab study suggests a third dose (booster) of the Pfizer–BioNTech vaccine may be necessary to provide an adequate immune response to the Omicron variant.

Press release: Pfizer and Biontech provide update on Omicron variant

Commentaries:

Omicron likely to weaken COVID vaccine protection – Nature

Pfizer-BioNTech says COVID booster should protect against Omicron – CIDRAP

Expert reaction to press release from Pfizer-BioNTech about omicron and neutralising antibody titres after two and three vaccine doses – Science Media Centre

Covid: Pfizer says booster shot promising against Omicron – BBC

Pfizer-BioNTech Covid-19 shot loses power against Omicron variant, but booster restores protection – STAT