• Drugmaker AstraZeneca is racing to adapt its Covid-19 vaccine in the face of new variants of the virus.
• The process has become more urgent after a small-scale study found that it was less effective at protecting against the more virulent strain discovered in South Africa.
• Vaccine makers are working on second-generation shots to target variants.

LONDON — Drugmaker AstraZeneca is racing to adapt its Covid-19 vaccine in the face of new variants of the virus, with the process becoming more urgent after a small-scale study found that it was less effective at protecting against the more virulent strain discovered in South Africa.

The country said it would suspend the use of the shot in its vaccination program after a study, published Sunday and not yet peer reviewed, found that the vaccine offered "minimal protection" against mild to moderate disease caused by the mutation found in South Africa.

Researchers from the University of Witwatersrand and others in South Africa, and the University of Oxford, noted that the study was small, involving only around 2,000 volunteers who had an average age of 31. Oxford University said "protection against moderate-severe disease, hospitalization or death could not be assessed in this study as the target population were at such low risk."

Vaccine makers had already started developing second-generation Covid vaccines aimed at targeting new variants of the virus, and experts say it shouldn't be too tricky to tweak existing vaccines in a matter of six weeks to cover mutations. Shares of AstraZeneca were trading 0.6% higher on London's FTSE 100 index Monday.

Sarah Gilbert, professor of vaccinology at the University of Oxford, which developed the vaccine with AstraZeneca, commented on Sunday that "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."

The variant, known formally as the B.1.351 mutation, was first detected in South Africa in October and has become dominant in the country.

Several cases have been found elsewhere, sending health authorities scrambling to stop the spread of the mutation that is proven to be more infectious. There had already been concerns that this variant could be more resistant to coronavirus vaccines developed over the last year.

As it suspended use of the AstraZeneca-Oxford University vaccine, the South African government will offer vaccines produced by Johnson & Johnson and Pfizer instead.

In late January, Johnson & Johnson reported that its single-dose shot was 57% effective in one of its clinical trials in South Africa where 95% of Covid infections were from the B.1.351 lineage. For comparison, the vaccine was found to be 72% effective in the U.S. trial.

Pfizer-BioNTech and Moderna have reported early indications that their vaccinations offer protection against new variants found in South Africa and the U.K.

On Friday, Oxford released details of a separate study that showed its vaccine was effective against a variant that was discovered in southeast England, and one that has now become the dominant strain in the U.K.

Andrew Pollard, professor of paediatric infection and immunity and chief investigator on the Oxford vaccine trial, said data from the trials of its vaccine in Britain "indicate that the vaccine not only protects against the original pandemic virus, but also protects against the novel variant, B.1.1.7, which caused the surge in disease from the end of 2020 across the UK."