The Oxford / AstraZeneca Covid-19 vaccine does not appear to protect against mild and moderate disease caused by the viral variant first identified in South Africa, according to a study to be published Monday.
While none of the more than 2,000 patients in the study died or were hospitalized, the findings, which have not yet been peer-reviewed, could complicate the race to roll out vaccines when new strains emerge.
In both the human and vaccinees’ blood tests, the shot showed significantly reduced efficacy against the 501Y.V2 viral variant, which is dominant in South Africa, according to the Financial Times randomized, double-blind study.
A two-dose regimen [the vaccine] did not show protection against mild to moderate Covid-19 due to [the South African variant]The study says, adding that efficacy against severe Covid-19, hospitalizations and deaths had not yet been established.
The so-called Kent variant – which Oxford University said Friday was just as susceptible to the vaccine as older variants of the virus – has now acquired the E484K mutation, which is present in the variants that spike the Covid-19 in Brazil and South Africa.
There are caveats to the study, as the sample size was relatively small. The study, led by the University of Witwatersrand in South Africa and the University of Oxford, enrolled 2,026 HIV-negative individuals, with a median age of 31. Half of the group received at least one dose of placebo, the other half received at least one dose of vaccine.
Tulio de Oliveira, head of the Network for Genomic Surveillance in South Africa, told the Financial Times the findings were a “wake-up call to contain the virus and increase the world’s response rate to Covid-19” .
Health authorities around the world hope that vaccines will reduce or completely eliminate the burden of hospitalization, thereby easing lockdowns.
While important, it is relatively less urgent to avoid symptomatic, but milder infection that does not progress to hospitalization.
Any setback to the efficacy of the Oxford / AstraZeneca vaccine would be especially critical for the developing world as the partners produce billions of doses during the nonprofit pandemic.
The vaccine still appears to be completely effective in preventing hospitalization and death from other variants of the coronavirus, data from other studies show.
AstraZeneca declined to comment, referring questions to Oxford. Oxford declined to comment on the results of the study, saying only that it was working with partners around the world, including in South Africa, to evaluate the effects of new variants on the first generation of its Covid vaccine.
“Oxford is working with AstraZeneca to optimize the pipeline required for a voltage change, should the need arise,” said the university. “This is the same problem faced by all vaccine developers, and we will continue to monitor the emergence of new variants emerging in preparation for a future strain change.”
The University of the Witwatersrand did not respond to requests for comment. The South African Ministry of Health did not immediately respond to a request for comment.
While all the Covid-19 vaccines to date have largely held up against the B.1.1.7 variant emerging in the UK, the strain originating in South Africa is more concerning. Both Johnson & Johnson and Novavax have said their vaccines were less effective against the strain in clinical trials conducted in South Africa. In trials, both vaccines provided complete protection against serious illness and death associated with Covid-19.
Moderna has said it will test a booster shot and a reconstituted vaccine to target the South African variant, after studies showed the vaccine was significantly less effective.
BioNTech / Pfizer said their vaccine was slightly less effective in a lab study of a pseudovirus with some mutations of the 501Y.V2 variant, but have not published results from tests against the variant itself.
The 501Y.V2 variant, dominant in South Africa, has recently been discovered in countries around the world, including the US and UK.
South Africa last week received 1 million doses of the AstraZeneca vaccine, the first Covid-19 vaccines to arrive in the country, as part of a 1.5 million dose order from India’s Serum Institute.