South Africa halted the use of the AstraZeneca-Oxford coronavirus vaccine on February 7 after evidence emerged that the vaccine did not protect clinical trial volunteers from mild or moderate illness caused by the more contagious virus variant that was first seen there.
Scientists in South Africa said Sunday that a similar problem held for people who had been infected by earlier versions of the coronavirus: The immunity they acquired naturally did not appear to protect them from mild or moderate cases when they were reinfected by the variant, known as B.1.351. The developments, coming nearly a week after 1 million doses of the AstraZeneca-Oxford vaccine arrived in South Africa, were an enormous setback for the country, where more than 46,000 people are known to have died from the virus.
The number of cases evaluated as part of the studies outlined by South African scientists Sunday was low, making it difficult to pinpoint just how effective or not the vaccine might be against the variant. And because the clinical trial participants who were evaluated were relatively young and unlikely to become severely ill, it was impossible for the scientists to determine if the variant interfered with the AstraZeneca-Oxford vaccine’s ability to protect against severe COVID-19, hospitalizations, or deaths.
The scientists said, however, that they believed the vaccine might protect against more severe cases, based on the immune responses detected in blood samples from people who were given it. If further studies show that to be the case, South African health officials will consider resuming the use of the AstraZeneca-Oxford vaccine, they said.