No need for 4th Covid jab yet: UK experts
Protection against mild symptomatic infection is more short-lived, the data revealed.
That drops to around 30 per cent by about three months, it added.
According to the Agency, figures also show why it is important to get a booster dose if you have only had two doses so far.
With just two vaccine doses, protection against severe disease drops to around 70 per cent after three months and to 50 per cent after six months.
The Joint Committee on Vaccination and Immunisation (JCVI), which advises on vaccine policy, said the priority, therefore, remains to get first, second and third doses to those who have not already had them.
This is despite some countries such as Israel starting to give fourth Covid shots to manage the highly infectious Omicron variant that is causing rising numbers of infections around the globe.