JOHANNESBURG: One of the South African government's top advisers on COVID-19 vaccines said on Friday that the Pfizer shot was "still a very good vaccine", despite a study showing the dominant local virus variant may reduce its protective antibodies.

Barry Schoub, chairman of the Ministerial Advisory Committee on vaccines, told Reuters that the two-thirds reduction in protective antibodies mentioned in the study "means there is quite a significant remnant neutralising potency".

The advisory committee held its regular weekly meeting on Thursday and discussed the laboratory study, which was published in the New England Journal of Medicine this week.

While it has not been established in a clinical trial that the Pfizer vaccine protects against the more contagious 501Y.V2 variant first identified late last year, "we can have a reasonable extrapolation because it's such a potent stimulator of the immune system and the fact that in the laboratory it was only reduced by two-thirds", Schoub said.

Authorities would monitor closely those who get the Pfizer vaccine, he added.

South Africa is counting on the Pfizer shot, developed with German partner BioNTech, to step up its vaccination programme after administering its first Johnson & Johnson doses on Wednesday.

AstraZeneca vaccinations are on hold after a small local trial found the shot offered minimal protection against mild to moderate illness from the 501Y.V2 variant.

Health Minister Zweli Mkhize said on Wednesday that South Africa was expecting 500,000 doses of the Pfizer vaccine initially and about 7 million doses by June.

South Africa, with nearly 1.5 million cases and over 48,000 deaths, has recorded almost half the COVID-19 fatalities and over a third of confirmed infections in Africa. It lagged richer Western nations in launching its immunisation campaign.