COVID-19 vaccine protection wanes after three months, study suggests
The findings - drawn from datasets in two countries - suggest that booster programmes are needed to help maintain protection from severe disease in those vaccinated with Oxford-Astra Zeneca, experts say.
On 26 November 2021, WHO designated the variant B.1.1.529 a variant of concern, named Omicron, on the advice of WHO's Technical Advisory Group on Virus Evolution (TAG-VE). This decision was based on the evidence presented to the TAG-VE that Omicron has several mutations that may have an impact on how it behaves, for example, on how easily it spreads or the severity of illness it causes.