Director of Public Health rates previous vaccines "five out of 10"
It's hoped the "next generation" of Covid vaccines will be more effective in the fight against the virus.
Director of Public Health, Professor Hugo van Woerden, says the fourth dose which will be offered to some this winter will likely be of this new generation.
The newer jabs are supposedly more generalised and able to fight off different variants of the virus - in a similar way to the yearly flu vaccine.
The UK's Joint Committee on Vaccination and Immunisation (JCVI) has recommended an Autumn booster programme.
On the Island, several groups are eligible for another booster, namely those aged 75 and over, those aged 12 and over who are immunosuppressed and those residing in care homes for older people.
Hugo van Woerden spoke to Manx Radio: