South Africa suspends AstraZeneca COVID-19 vaccines after study finds limited impact on variant

South Africa has temporarily suspended use of a coronavirus vaccine developed by AstraZeneca and Oxford University after preliminary findings showed the jab had little impact on curbing mild-to-moderate illness due to a variant strain.

The announcement from South Africa’s Health Minister Dr. Zweli Mkhize on Sunday followed shortly after the country received 1 million doses of the AstraZeneca vaccine, which was intended to rollout this week.

Researchers investigated the effectiveness of the vaccine given the resurgence of cases driven by a more transmissible and likely more virulent variant called B.1.351.


Findings stemmed from a Phase 2 trial with 2,000 healthy participants aged 18 to 65. Volunteers either had two doses of vaccine or a placebo. Prof. Shabir Madhi with the University of the Witwatersrand ultimately suggested that the vaccine did not protect against mild-to-moderate COVID-19. However, scientists still remain hopeful that the vaccine may offer protection against severe courses of disease.

Madhi said before the variant emerged, the vaccine was showing “tremendous potential” in reducing mild-to-moderate illness with about 75% effectiveness, until the end of October.

Results show that variant cases later cropped up among 19 of 748 vaccinated participants, and 20 cases occurred among 714 participants given the placebo, suggesting the vaccine was not effective in protecting against mild-to-moderate illness. These results translate to a vaccine efficacy of 10.4%, though this figure may fluctuate with a larger trial size.


A spokesperson for AstraZeneca told Fox News that the study couldn’t determine vaccine efficacy among severe cases given its trial design, as the researchers also noted.

“This was a small study with predominantly young (average 31 years) healthy adults, where severe disease is not predominant,” reads the emailed statement from AstraZeneca. “No severe disease or hospitalisation was observed in the vaccine or control participants. We believe our vaccine will protect against severe disease caused by the new B.1.351 variant, as neutralising antibody activity is equivalent to that seen with other COVID-19 vaccines that have demonstrated activity against more severe disease, and particularly when the dosing interval is optimised to 8-12 weeks. We are working closely with the South African Ministry of Health on how best to support the evaluation of COVID-19 Vaccine AstraZeneca against severe disease of the B.1.351 variant, and how to bring this vaccine to the South African people.”


Mkhize called the findings “disappointing,” because the country was ready to roll out the vaccines, but he said health care workers will instead receive vaccines developed by Johnson & Johnson and Pfizer. The health minister said scientists are determining the best approach for the AstraZeneca vaccines, and will return with a proposal.

Johnson & Johnson recently announced that its single-shot coronavirus vaccine was 66% effective in preventing moderate-to-severe COVID-19 in a global trial, and 57% effective in South Africa at 28 days post-vaccination. Early results suggest Pfizer’s vaccine will remain effective against the variant, though the company is working on a variant booster shot to better protect against strains.

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