Second booster doses of the Covid-19 vaccine will soon be available for those most at risk of getting very sick from an infection.

The Response Minister Chris Hipkins says several hundred thousand people will be eligible for the extra vaccination, including: older people, those living in aged and disabled care facilities, and the severely immunocompromised.

Mr Hipkins says the rollout will begin in mid June, after the Medicines Act is amended.

Vaccinologist associate professor Helen Petousis-Harris, who's a member of the Ministry of Health's COVID-19 Vaccine Technical Advisory Group spoke to Māni Dunlop.