Calls for people to have booster shots have intensified around the world as countries rush to contain the spread of the Omicron variant amid record case rates.
Researchers at Imperial College London published a study last week indicating a booster shot could provide up to 80% protection against the Omicron variant.
The modelling, which involved both AstraZeneca and Pfizer vaccines, showed vaccine effectiveness of between 0% and 20% after two doses, and between 55% and 80% after a booster dose. The study was based on limited information on Omicron.
Whereas two Covid jabs do not offer strong protection against symptomatic infection from Omicron, those who have received a booster jab remain up to 70% protected.
The analysis shows that the AstraZeneca and Pfizer vaccines provide much lower levels of protection against symptomatic infection from Omicron than Delta, making the double-jabbed vulnerable to the variant.
In a study published in The Lancet medical journal on Monday, researchers found the protection afforded by two doses of the AstraZeneca vaccine began to wane three months after the second jab. However, the Omicron variant was not circulating at the time of the study.
