South Africa halts AstraZeneca vaccine rollout over preliminary efficacy data
South Africa halted its rollout of the AstraZeneca-Oxford COVID-19 vaccine after preliminary data showed that it provided minimal protection against mild to moderate disease caused by the dominant variant circulating in the country.
The announcement was made Sunday by South Africa Health Minister Zweli Mkhize, MBChB.
According to researchers at the University of the Witwatersrand in Johannesburg, which is running a trial of the vaccine in South Africa, early data from a study of 2,000 patients aged between 18 and 65 years showed a substantial drop in the vaccine’s neutralizing activity against the SARS-CoV-2 variant first identified in South Africa, B.1.351, following the administration of two doses.
Researchers noted that the study did not assess the vaccine’s efficacy against severe disease from the variant. The vaccine demonstrated high efficacy against wild-type SARS-CoV-2, they said.
The results have not been published, other than in a news release from the university, but have been submitted as a pre-print paper prior to peer review, the release said.
“This study confirms that the pandemic coronavirus will find ways to continue to spread in vaccinated populations, as expected, but taken with the promising results from other studies in South Africa, such as those using a similar viral vector, vaccines may continue to ease the toll on health care systems by preventing severe disease,” Andrew Pollard, BBS, PhD, professor of pediatric infection and immunity and chief investigator on the Oxford vaccine trial, said in the release.
B.1.351 is one of several emerging SARS-CoV-2 variants circulating globally. It was identified in the United States for the first time last month and has been described by National Institute of Allergy and Infectious Diseases Director Anthony S. Fauci, MD, and others as the most worrisome SARS-CoV-2 variant. The U.S. has implemented travel restrictions in response to the variants, although experts have warned they will continue to spread even with these measures in place.
Experts have stressed that vaccination is the best countermeasure to the emerging variants. In a White House press briefing on Monday, Fauci said vaccines have proven to be effective against another variant first identified in the United Kingdom, which is projected to become the most dominant SARS-CoV-2 virus in the U.S. by March, and the hope is to get as many people vaccinated before the B.1.351 variant becomes dominant.
South Africa COVID-19 advisor Salim Abdool Karim, MB BCh, PhD, noted that future vaccines are expected to have broader coverage to offer protection against variants, but that they “will take a little longer to develop.”
“We can still proceed with our rollout [of the AstraZeneca-Oxford] vaccine but we need to do it wisely by taking a stepped approach,” he said, according to a transcript provided by the South Africa Department of Health.
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The data are quite concerning because they suggest that a two-dose regimen of the vaccine provided only minimal protection against mild/moderate COVID-19 infection with the B.1.351 variant. The authors did not assess the impact of the vaccine against severe disease, hospitalization and death. Overall this is concerning, but I need to see further data.
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