Pfizer slid in premarket trading asOxford study found two vaccine doses wouldn’t protect from Omicron infection.A new study from researchers at the University of Oxford has found two doses of either the Pfizer or AstraZeneca COVID-19 vaccine may not be enough to protect against infection from the Omicron variant. The data offers no indication of protection from severe disease, but shows two doses will not be enough to prevent Omicron infection in most people.