Britain on Monday indicated that scientists are exploring the possibility of an additional booster jab for later in the year in order to tackle any Covid-19 variants that may try to escape the immunity levels provided by the current vaccination programme, such as the South African variant.
UK Vaccine Deployment Minister Nadhim Zahawi said a "booster in autumn" could be required but urged the public to have full confidence in the vaccines currently being administered in the country – the Pfizer/BioNTech and Oxford/AstraZeneca – which have now covered 12 million people in the highest risk categories.
"Our brilliant scientists and medical advisers are now working on the potential for new versions of existing vaccines to offer further protections against Covid variants," said Zahawi, writing in 'The Daily Telegraph'.
"But we should bear in mind that recent studies show the vaccines being deployed right now across the UK appear to work well against the Covid-19 variants currently dominant in the UK.
"In terms of other variants, not in the UK, we need to be aware that even where a vaccine has reduced efficacy in preventing infection there may still be good efficacy against severe disease, hospitalisation, and death. This is vitally important for protecting the healthcare system," he said.
His intervention came as a small sample study conducted with the Oxford/AstraZeneca vaccine, which also has a tie-up with the Serum Institute of India, found in South Africa that it may not be as effective in preventing mild to moderate Covid-19 against the local variant. However, experts have stressed that the vaccine's protection against severe disease and death remains promising.
"This study confirms that the pandemic coronavirus will find ways to continue to spread in vaccinated populations, as expected, 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," said Andrew Pollard, Professor of Paediatric Infection and Immunity, and Chief Investigator on the Oxford vaccine trial.
"We are working with AstraZeneca to optimise the pipeline required for a strain change should one become necessary," added Sarah Gilbert, Professor of Vaccinology at the University of Oxford.
As part of the pre-print study of 2,000 volunteers, researchers from the University of Witwatersrand and others in South Africa and the University of Oxford found that viral neutralisation by the ChAdOx1 nCoV-19 coronavirus vaccine against the B.1.351 coronavirus variant, or the South African strain, were substantially reduced when compared with the original strain of the coronavirus. This indicates that the mutations in the virus seen in South Africa will allow ongoing transmission of the virus in vaccinated populations.
"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," said 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.
Earlier, Oxford University scientists have confirmed in a separate study that their ChAdOx1 nCoV-19 coronavirus vaccine has shown efficacy against the UK variant, dubbed the B.1.1.7 'Kent' coronavirus strain.
Prof. Gilbert explained that coronaviruses are less prone to mutation than influenza viruses, but it was always expected that as the pandemic continues, new variants will begin to become dominant amongst the viruses that are circulating and that eventually a new version of the vaccine, with an updated spike protein, would be required to maintain vaccine efficacy at the highest level possible.
Meanwhile, the UK government confirmed that more than 12 million people have now received at least one of the two-dose vaccines against Covid-19.
In its latest messaging, the government has also stressed that coronavirus vaccines will be offered to everyone living in the UK free of charge, regardless of their immigration status, and have urged people in the country illegally to know they will not be at risk of deportation if they come forward for a jab.
It comes as the daily death rates from the virus have shown a fall in the past few days, with 373 people dying on Sunday and taking the UK's death toll lose to 112,000.