Pfizer, J&J Covid-19 vaccines more effective against Delta than Beta variant, say South African experts

The Covid-19 vaccines by US pharma majors Pfizer and Johnson & Johnson (J&J) that are being used in South Africa are more effective against the Delta variant of the coronavirus than the Beta strain, experts have said.

The Beta variant, which was first detected in South Africa, caused a second wave at the beginning of this year whereas the Delta variant, first detected in India, is driving the current third wave in South Africa, resulting in increased lockdown restrictions as the number of infections and deaths have already surpassed those of the previous two waves.

In a media briefing led by Acting Health Minister Mmamoloko Kubayi on Friday, experts said that results in both laboratory research and field studies had shown that the vaccines were effective against the Delta virus.

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“What we have seen in the in vitro work is that the J&J vaccine works better against the Delta variant and gets better over time where both the Delta and Beta variants are concerned,” said Professor Glenda Gray, President and CEO of the South African Medical Research Council.

Gray said there was no need yet to get a booster jab of the J&J vaccine.

Referring to the studies so far, she said that a single shot worked just as well as two doses given to health care workers over a period.

“Right up to eight months we may say that we have durable immune responses as measured in people who we are following up over time,” she said.

“Quite unequivocally, the single shot of J&J vaccine works against both the Delta and the Beta variants of concern at eight months. So this is just to reassure the public that we don’t need to boost the J&J vaccine just yet, but we need to keep following up the participants to see when the durability of the immune response wanes,” Gray said.

Professor Penny Moore of the University of Witwatersrand confirmed that existing laboratory data suggested that the vaccines currently being used in South Africa work better against the Delta variant than they have against the Beta variant.

“In a large measure, our epidemic now in South Africa is driven by the Delta variant, so it is very crucial that we understand how that variant reacts to the various vaccines that we have in South Africa.

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“Against the Pfizer vaccine, the antibodies were really good at 1,000 (but) with the AstraZeneca vaccine the antibodies dropped right down to 146, indicating that the vaccine would not work so well against the Beta variant. But when we look at the Delta variant which is now circulating in South Africa, the numbers have gone back up again,” Moore said.

WHO earlier expressed concern about possible new waves in Europe due to the Delta variant, which has been detected in over 25 countries around the globe.

The Delta variant is more transmissible than the previous two variants.

With vaccine stocks running out as vaccination campaigns are stepped up, the health minister said that South Africa will get delivery of 2.1 million more Pfizer doses this month, together with 500,000 Johnson & Johnson (J&J) vaccines that are still due for delivery.

The epicentre of South Africa’s third wave is the economic hub of Gauteng Province.

A two-week lockdown that started on Monday has prohibited travel into or out of the province except under special circumstances to contain the exponentially rising infections and deaths.

By Friday, South Africa had passed two million infections. With 381 deaths from Covid-19 related issues overnight, the current death toll has touched 61,029.