Covid-19 News South Africa

AstraZeneca shot on hold, data shows lower efficacy against SA variant

Plans to rollout the AstraZeneca vaccine have been paused after trials showed it to be less effective against mild to moderate forms of the B.1.351 coronavirus variant first identified in South Africa.

One-million doses of the AstraZeneca shot, intended for healthcare workers in the first phase of the country's vaccine programme, arrived amid much fanfare from the Serum Institute of India on 1 February.

The delay was announced by health minister, Zweli Mkhize, in a press conference on Sunday. "What does that mean for our vaccination programme which we said will start in February? The answer is it will proceed."

Instead, the vaccines developed by Johnson & Johnson (J&J) and Pfizer will come into play coming weeks while experts consider how the AstraZeneca shot can be deployed.

"From next week for the next four weeks we expect that there will be J&J vaccines, there will be Pfizer vaccines. So what will be available to the health workers will be those vaccines."

"The AstraZeneca vaccine will remain with us... Up until the scientists give us clear indications as to what we need to do," he added.

Trial

Shabir Madhi, professor of vaccinology at Wits University, who was part of the press conference, said the results from the AstraZeneca trials were “disappointing” and a reality check.

Recruiting over 2,000 participants started towards the end of the first wave, but while the study was under way the new variant started spreading in the country -especially in the Eastern Cape and became a dominant part of the second wave of the pandemic.

The evidence collected showed that the AstraZeneca vaccine was less effective against the new variant. Before 31 October, when the trial began – results showed promise and the likelihood of protecting against mild cases of the virus. Results had shown that the vaccine was 75% effective with a single dose in 14 days. These same results could not be replicated based on the new variant.

He said the question of whether the AstraZeneca vaccine would be effective against severe forms of the virus had not been answered as the study did not aim to answer that question. A larger study would be needed, Mahdi said.

He said had the virus not mutated, the results would have been promising.

Other options

Madhi said it was not all “doom and gloom” as vaccines like the one-dose vaccine offered by J&J offered more promising effectiveness against the SA variant and severe forms of the virus.

Professor Glenda Gray agreed that early results were more promising and the vaccine could be a “silver bullet”.

The single-dose vaccine was shown to be 85% effective in preventing severe disease and death in the 501Y.V2 variant.

“We are in advanced discussions to further evaluate the single shot Covid vaccine in South Africa in an accelerated manner,” said Gray.

The country would also get 9-million doses from Johnson & Johnson, 20-million from Pfizer and 12-million from the Covax facility.

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