The Omicron Covid variant makes all major vaccines ‘markedly’ weaker at preventing infection after two doses, another lab study has found.
Columbia University researchers tested the mutant strain against the blood of people vaccinated with two doses of the four big brands — Pfizer, Moderna, Johnson & Johnson and AstraZeneca.
They also looked at people given a booster of one of the two mRNA vaccines as part of their study, which has not been peer-reviewed or published in a scientific