South Africa Halts AstraZeneca Vaccine After Trial Shows Only 22% Efficacy

South Africa will temporarily halt the rollout of AstraZeneca Plc’s vaccine and accelerate its supply of shots from Johnson & Johnson and Pfizer Inc. after a trial showed the shot had limited efficacy against a new variant of the virus first identified in the country late last year.

The South African arm of the trial found that the shot from Astra and the University of Oxford had only 22% efficacy against mild and moderate illness, lead researcher Shabir Madhi said on Sunday. There was no conclusive data showing whether the vaccine protects against severe illness, mainly because of the relative youth of the 2,000 trial participants, he said.

“We need to recalibrate our expectations,” Madhi said. “The results are very much a reality check.”

The data has cast doubt over the usefulness of the Astra-Oxford shot, which was the first coronavirus vaccine to arrive in South Africa last week and due to be rolled out by mid-February to vaccinate health workers. More than 90% of new cases in the country have the more contagious B.1.351 variant, which has been found in at least 30 other countries worldwide. Still, it would be “reckless” to dispose of the vaccine, which can be updated, Madhi said.

“Our scientists must tell us what do we do with AstraZeneca and how quickly can we bring it back to stream,” Health Minister Zweli Mkhize said. “The plan is to find out from scientists on how to deal with this going forward.”

The J&J vaccine is approved for study use in South Africa and will now be deployed to inoculate health staff “as part of a research project,” the government said in a statement Monday.

Scientists and governments globally are wrestling with a growing number of mutations of Covid-19, taking steps to tweak the current flock of vaccines to create booster shots that could be used later this year to ensure continued protection beyond initial vaccination. Sarah Gilbert, who led the team that created the Oxford-Astra vaccine, said Sunday that work was already underway to adapt the vaccine to deal specifically with the South African variant, with plans for it to be available by autumn.

From the trial of about 2,000 participants, investigators were able to analyze data from 1,749 volunteers, all aged 18 to 65 with a median age of 31, according to the data presented by Madhi. About 68% of volunteers were of black African descent, 14% were white and 16% mixed race.

Madhi said that due to the age of the participants and low prevalence of underlying health conditions making them less likely to have a serious case of Covid-19, “the study was not really designed to determine whether a vaccine would protect against severe Covid or not.” If the vaccine does protect against severe disease and hospitalization, it could still be key to helping prevent deaths and health systems from becoming overrun.

Authorities plan to accelerate the arrival of other products to vaccinate health workers, according to Glenda Gray, president of the South African Medical Research Council. The government has secured 9 million doses from Johnson & Johnson and 20 million doses from Pfizer Inc., which were expected to arrive from June and May respectively.

Vaccines for health workers from both drugmakers should now arrive within four weeks, according to Mkhize. The country expects a resurgence of infections in winter, which starts in June.

The start of South Africa’s vaccination program is only likely to be slightly delayed but it may be rolled out slower than initially planned, Salim Abdool Karim, co-chair of the nation’s Covid-19 ministerial advisory committee, told a World Health Organization briefing on Monday. The country may consider issuing AstraZeneca shots in stages until a clearer picture of its efficacy emerges, he said.

Africa’s most industrialized economy has also secured an additional 4.3 million vaccines from the Covax facility, which are due in March. The program has allocated about three to five million doses of the Astra shot to the nation, the health ministry said last week, with supply starting in mid-February.

With almost 1.5 million confirmed cases and more than 46,000 deaths, South Africa is the hardest-hit country on the continent.

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