South Africa Halts AstraZeneca Vaccine Rollout Over Effectiveness Doubts With New Variant

South Africa is pressing pause on its planned vaccine rollout using the Oxford-AstraZeneca vaccine. It had planned to start vaccinating front-line health care workers next week but is putting that on hold after a small clinical trial found that it provided “minimal protection” against mild to moderate coronavirus infections from the new variant that is dominant in the country. The variant, which accounts for more than 90 percent of the country’s COVID-19 cases, appears to be more infectious and there is evidence to suggest it could be more virulent as well. Known as B.1.351, the variant has spread to at least 32 countries, including the United States.

Before the more contagious variant had spread widely in South Africa, the vaccine had shown to have an efficacy of around 75 percent. But a later analysis that took into account only infections by this new variant found that the vaccine only provided a 22 percent lower risk of developing mild to moderate COVID-19 compared to the placebo. That is well below the 50 percent that is widely seen as the threshold to consider a vaccine to be effective. The study mostly involved young adults so it didn’t analyze whether it helped to prevent severe cases of COVID-19.

South Africa has received one million doses of the AstraZeneca vaccine. Now the government says it will wait to figure out what the best course of action will be. Meanwhile, it will fast track the rollout of the Johnson & Johnson vaccine that has shown to have more efficacy against the new variant, although at a lower rate than in the United States. Pfizer and Moderna have also said preliminary studies suggest their vaccines are less effective against B.1.351. The data have raised alarm bells around the world amid concerns that the new coronavirus variants that are emerging could make some of the vaccines less effective. Experts in South Africa said they have also found that people who had been infected with other versions of the coronavirus did not appear to have protection from being reinfected by the new variant.

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