Oxford/AstraZeneca Covid-19 vaccine provides minimal protection against South African variant

The University of Oxford and AstraZeneca’s Covid-19 vaccine only provides minimal protection against the South African variant of Covid-19, according to data from a small-scale study.

Researchers from the University of Witwatersrand and others in South Africa worked alongside the University of Oxford to analyse how effective a two-dose regimen of the ChAdOx1 nCoV-19 vaccine is against a mild-moderate infection from the South African variant of Covid-19.

The study consisted of approximately 2,000 volunteers with an average age of 31 years old. Mild disease was defined as at least one symptom of Covid-19. The study did not analyse protection against moderate-severe disease, and the low risk of the target population meant that hospitalisation or death could not be assessed.  

Whilst the vaccine was found to have high efficacy against the original coronavirus strain in South Africa, protection as substantially reduced when tested against the B.1.351 coronavirus variant.

The University of Oxford has now said it begun work to produce a second generation of the vaccine which has been adapted to target variants of the coronavirus with mutations similar to B.1.351.

The researchers says that these early data confirm theories that mutations in the virus seen in South Africa will allow Covid-19 to spread through vaccinated populations.

Shabir Madhi, professor of Vaccinology and Director of the Vaccines & Infectious Diseases Analytics (VIDA) Research Unit at University of the Witwatersrand, and chief investigator on the trial in South Africa said: “Recent data from a study in South Africa sponsored by Janssen which assessed moderate to severe disease, rather than mild disease, using a similar viral vector, indicated that protection against these important disease endpoints was preserved.

“These findings recalibrate thinking about how to approach the pandemic virus and shift the focus from the goal of herd immunity against transmission to the protection of all at risk individuals in population against severe disease.”

Sarah Gilbert, professor of Vaccinology at the University of Oxford said: “Efforts are underway to develop a new generation of vaccines that will allow protection to be redirected to emerging variants as booster jabs, if it turns out that it is necessary to do so.”

“We are working with AstraZeneca to optimise the pipeline required for a strain change should one become necessary. This is the same issue that is faced by all of the vaccine developers, and we will continue to monitor the emergence of new variants that arise in readiness for a future strain change.”