British scientists have warned the country's first coronavirus vaccine won’t be the “silver bullet” that ends the pandemic and could only alleviate symptoms instead of giving full immunity.
England’s chief medical officer Chris Whitty said he believed the vaccine may only be effective 40 to 60 per cent of the time - similar to the flu jab.
University of Oxford scientists have set the vaccine a minimum effectiveness of 50 per cent, claiming a jab that could cut the pandemic in half would be hugely beneficial.
However, a UK-based research institute said the government should “manage people’s expectations” and stressed the vaccine may not prevent people from catching Covid-19.
Charlie Weller, head of vaccines at the Wellcome Trust, told The Times the jab was "not going to be a perfect solution".
“They are likely not to provide full immunity or be fully effective for every age group and for every person. That’s a big ask — that you’re 100 per cent effective on every age group and every person, so it’s likely that we won’t get that,” she said.
She added: “We need to manage everyone's expectations on what these first frontrunners of vaccines can actually do.”
The warnings came as a US study claimed coronavirus could be mutating to get around mask-wearing and other forms of social distancing.
David Morens, a virologist at the National Institute of Allergy and Infectious Diseases, said a future vaccine may need to be “tinkered with” as there was a strong possibility the virus had become more contagious.
He said the virus had potentially improved in responding to social distancing as it worked its way through the population.
"Wearing masks, washing our hands, all those things are barriers to transmissibility or contagion, but as the virus becomes more contagious it statistically is better at getting around those barriers," he told the Washington Post.
Mr Morens warned of implications for future vaccines if the virus was able to mutate and combat immunity.
He said: “If that happened, we’d be in the same situation as with flu. We’ll have to chase the virus and, as it mutates, we’ll have to tinker with our vaccine.”