A call to action to the nearly one-million Kiwis yet to receive their first Covid booster jab

Data shows a first booster significantly improves the ability to neutralise variants, including Omicron, after a period of waning immunity following a second dose.

It comes as Medsafe grants provisional approval for two new Pfizer booster vaccines - one for Omicron BA1, and another for the BA4-and-5 sub-variants.

Vaccine Alliance Clinical Director, Doctor Maia Brewerton says many people believe a booster's unnecessary, if they've already been infected.

She says if it's been more than three months since infection -- a booster's critical to increase immune response.