Over concerns that the AstraZeneca vaccine showed low efficacy in one clinical trial, the vaccine's inoculation program was halted in South Africa.
During the briefing, Shabir Madhi, Professor of Vaccinology at the University of the Witwatersrand and Chief Investigator on trial in South Africa, presented the efficacy levels of Oxford/AstraZeneca COVID-19 vaccine (AZD1222) against the COVID-19 variant Beta(B.1.351, also known as 501Y.V2). The beta variant was the first identified variant in South Africa. The AstraZeneca COVID-19 vaccine's efficacy has been demonstrated to be diminishing, he claimed. The clinical study on mild to moderate disease declined to 22 percent from 66 percent.
The University of the Witwatersrand in South Africa and the U.K.'s Oxford University released the non-peer-reviewed study on February 7, 2021. The results said, "a two-dose regimen of the ChAdOx1 nCoV-19 vaccine provides minimal protection against mild-moderate COVID-19 infection from the B.1.351." This means the AstraZeneca vaccine did not work against mild and moderate illnesses. The Beta variant's efficacy against severe COVID-19 infection was not evaluated.
The study consisted of approximately 2,000 volunteers, with an average age of 31 years, and mild disease was defined as at least one symptom of COVID-19.
The BBC reported on February 8 that South Africa's Health Minister Zweli Mkhize said the "government would wait for further advice on how best to proceed with the AstraZeneca vaccine." Meanwhile, he said, the government would begin offering vaccines made by Johnson & Johnson and Pfizer. The vaccine rollout was suspended on February 7 until further findings.
On March 16, a peer-reviewed study was published at the New England Journal of Medicine on "Efficacy of the ChAdOx1 nCoV-19 COVID-19 Vaccine against the B.1.351 Variant." It stated that the trial found "two doses of the ChAdOx1 nCoV-19 vaccine had no efficacy against the B.1.351 variant in preventing mild-to-moderate COVID-19."
The vaccine efficacy was estimated in a secondary analysis. Regardless of variants, the trial's primary goal was to achieve vaccination effectiveness of at least 60 percent in preventing COVID-19 infection of any severity. The study says the "demographic and clinical profile of the enrolled participants contributed to the absence of severe COVID-19 cases." Therefore the study says the trial findings are inconclusive concerning "whether the ChAdOx1 nCov-19 vaccine may protect against severe COVID-19 caused by infection with the B.1.351 variant."
Sarah Gilbert, Professor of Vaccinology at the University of Oxford, said vaccines are being developed and updated for the future to protect one from the variants. The company was developing a pipeline that would allow it to adapt and change the vaccine in response to future strains.
In February, the World Health Organization (WHO) issued a warning to South Africa, urging against its prompt action. The vaccine's effectiveness cannot be measured by comparing one outcome with another, it suggested. On Twitter, Dr. Zweli Mkhize, the Minister of Health, underlined that they are not stating they will never utilize AstraZeneca vaccines but that further research is needed.
Until writing, the AstraZeneca vaccine was not provided in South Arica due to concerns about its efficacy against developing variants.
The COVID-19 pandemic has given rise to a lot of potentially dangerous misinformation. For reliable advice on COVID-19, including symptoms, prevention, and available treatment, please refer to the World Health Organization or your national healthcare authority.