Pfizer booster shots after being fully vaccinated with the AstraZeneca vaccine can increase protection from the omicron variant by up to 29 times, according to a new study.

The National Institute of Health observed 35 people aged 20 to 59 who were all boosted, finding that the levels of omicron-fighting antibodies increased two to three weeks after the third shot.

The level of omicron-fighting antibodies among 15 people who received the Pfizer vaccine after initially being fully vaccinated with AstraZeneca was nearly 29 times higher than with only two jabs.

Those antibodies in ten people who received Pfizer after mixing and matching the AstraZeneca vaccine with Pfizer for initial vaccination increased by ten-fold, while the level in those who received Pfizer for all three jabs shot up by 17-fold.

The survey also showed that a booster shot raises protection against the delta variant as well.