A fourth Covid jab is not yet needed, say UK experts, because booster doses continue to provide high protection against severe disease from the Omicron variant among older adults.
UK Health Security Agency data show three months after boosting, protection against hospitalisation remains at about 90 per cent for people aged 65 and over, the BBC reported.
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.