A three-dose course of AstraZeneca’s COVID-19 vaccine is effective against the omicron coronavirus variant, the pharmaceutical company said on Thursday, citing data from an Oxford University lab study.

The study, yet to be published in a peer-reviewed medical journal, showed antibody levels against imicron after the booster shot were higher than antibodies in people who had been infected with and recovered naturally from COVID-19.

After a three-dose course of the vaccine, neutralizing levels against omicron were similar to those against the virus’s delta variant after two doses, the company added.

The Anglo-Swedish drugmaker said researchers at Oxford University who carried out the study were independent from those who worked on the vaccine, Vaxzevria, with AstraZeneca.