Move comes after trial data shows jab offered limited protection against mild-moderate disease caused by new variant.
The Oxford/AstraZeneca COVID vaccine prevents death and serious illness and is effective against the main variants of the virus in the United Kingdom, a government official has said after South Africa suspended its roll-out of the shots.
Pointing out that the dominant strains in the UK were not the so-called South African variant, junior health minister Edward Argar told UK broadcaster Sky News on Monday that the vaccine was highly effective and there was no evidence that it was not preventing hospitalisations and severe illness in the country.
A day earlier, South Africa halted its plans to roll out the Oxford/AstraZeneca vaccine after data indicated it may give only minimal protection against mild-to-moderate infection caused by the country’s dominant 501Y.V2 strain of coronavirus.
The move stoked fears of a much longer cat-and-mouse battle with the pathogen, with the South African government saying it would await advice from scientists on how best to proceed.
South Africa’s move followed an analysis by scientists at the University of Witwatersrand in Johannesburg and the UK’s University of Oxford.
Analysis of infections by the South Africa variant showed there was a 22 percent lower risk of developing mild-to-moderate COVID-19 among those who received at least one dose of the vaccine compared with those given a placebo.
“This study confirms that the pandemic coronavirus will find ways to continue to spread in vaccinated populations, as expected,” said Andrew Pollard, chief investigator on the Oxford vaccine trial.
“But, taken with the promising results from other studies in South Africa using a similar viral vector, vaccines may continue to ease the toll on health care systems by preventing severe disease.”
The researchers said protection against moderate to severe disease, hospitalisation or death could not be assessed in the study as the target population were low-risk.
Professor Shabir Madhi, lead investigator on the AstraZeneca trial in South Africa, said the vaccine’s similarity to another produced by Johnson & Johnson, which reduced severe disease by 89 percent, suggested it would still prevent serious illness or death.
“There’s still some hope that the AstraZeneca vaccine might well perform as well as the Johnson & Johnson vaccine in a different age group demographic,” Madhi told BBC radio.
The Oxford/AstraZeneca vaccine is seen as a critical tool as it is cheap and easier to store and transport than some of the others on the market.
While thousands of individual changes have arisen as the virus mutates on replication and evolves into new variants, only a tiny minority are likely to be important or change the virus in an appreciable way, according to the British Medical Journal.
The so-called British, South African and Brazilian variants are causing scientists concern, as they appear to be more contagious than others.
Sarah Gilbert, professor of vaccinology at the University of Oxford, said efforts were under way to develop a new generation of booster shot vaccines that will allow protection against emerging variants.
“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,” she said.
If vaccines do not work against new variants, the world could face a longer and more expensive battle against the pandemic than previously thought.
“The message from the Oxford team is that existing vaccines could indeed be tweaked and very quickly, without the need for a large clinical trial afterwards,” said Al Jazeera’s Neave Barker in London, describing Gilbert’s comments as a “ray of light”.