AstraZeneca announced Saturday that preliminary data from a small test group indicates its vaccine offers only limited protection against mild illness caused by the South African variant of COVID-19.
As a result, Health Minister Zweli Mkhize, said in a briefing Sunday that South Africa will temporarily halt a planned rollout of the vaccine until there is more information on the vaccine’s efficacy. The country planned to administer an initial shipment of one million doses of the vaccine to health-care workers later this month.
“We do believe our vaccine could protect against severe disease,” an AstraZeneca spokesperson said, adding He the company has not been able “to properly ascertain its effect against severe disease and hospitalization given that subjects were predominantly young healthy adults.”
None of the participants in the study, 2,026 people with a median age of 31, required hospitalization or died from the virus, according to The Financial Times of London, which first reported the results.
Nevertheless, it was clear the vaccine provided very little protection against 501Y.V2, the South African variant of the SARS-CoV-2 virus, at least for those who contract the mild or moderate form of the illness.
Researchers said in their study led by South Africa’s University of the Witwatersrand and Oxford University, “a two-dose regimen of the ChAdOx1 nCoV-19 vaccine provides minimal protection against mild-moderate COVID-19 infection from the B.1.351 coronavirus variant first identified in South Africa.
The pre-print of the study was first published online late Sunday night.
“Efficacy against severe COVID-19 infection from this variant was not assessed. The analyses being submitted in the pre-print show the vaccine had high efficacy against the original coronavirus strain in South Africa.”
A further observation noted that researchers from the University of Witwatersrand and others in South Africa and the University of Oxford, UK “found that viral neutralization by sera induced by the ChAdOx1 nCoV-19 coronavirus vaccine against the B.1.351 coronavirus variant were substantially reduced when compared with the original strain of the coronavirus.
“These early data have been submitted for scientific peer-review, appear to confirm the theoretical observation that mutations in the virus seen in South Africa will allow ongoing transmission of the virus in vaccinated populations, as has been recently reported even in those with prior infection due to earlier circulating variants.”