Video report by ITV News Reporter Martha Fairlie
A Covid-19 vaccine has proven 90% effective in immunising against the virus, based on results from final "stage three" human trials.
The work of US drug giant Pfizer and German biotech firm BioNTech, developers said results showed "initial evidence of our vaccine’s ability to prevent Covid-19."
The FTSE 100 has jumped more than 5.5%, adding £82 billion to the value of its shares in the market’s best day since March, following the news.
According to Boris Johnson's spokesperson, the UK has procured 40 million doses of the Pfizer vaccine - with 10 million of those being manufactured and available to the UK by the end of the the year.
Dr Albert Bourla, Pfizer chairman and CEO, described it as "a great day for science and humanity".
He continued: "We are a significant step closer to providing people around the world with a much-needed breakthrough to help bring an end to this global health crisis.
"We look forward to sharing additional efficacy and safety data generated from thousands of participants in the coming weeks."
ITV News Science Editor Tom Clarke has more on the vaccine candidate
Downing Street welcomed the results from the vaccine tests as “promising” but urged caution.
The Prime Minister’s official spokesman said: “The results are promising and while we are optimistic of a breakthrough, we must remember there are no guarantees.
“We will know whether the vaccine is both safe and effective once the safety data has been published and only then can licensing authorities consider making it available to the public.
“In the meantime, the NHS stands ready to begin a vaccination programme for those most at risk once a Covid-19 vaccine is available before being rolled out more widely.
England’s chief medical officer Chris Whitty said there was “reason for optimism for 2021” following the announcement and hailed the "power of science" against the virus.
He added: "It is essential we continue to suppress COVID, but it is a reason for optimism for 2021.”
Kate Bingham, Chair of the UK Vaccines Task force, previously told ITV News the UK government had ordered 30 million doses of this particular vaccine.
Ian Jones, professor of virology at the University of Reading, said the Pfizer trial data shows “really impressive protection and no reported adverse events”. He said: “Of all the current vaccines currently in development the BioNtech product always looked like the most bang-per-buck as it is entirely focused on the part of the virus that binds to the human cell, the receptor binding domain." He added: “The trial data show excellent results in both of those areas, really impressive protection and no reported adverse events." The longevity of the response in all age groups, he said, will "not be known for some time" - a point echoed by Professor Azra Ghani, chair of infectious disease epidemiology at Imperial College London.
She welcomed the results but said that long-term efficacy data would come over coming weeks and months. “These new results represent the first demonstration of substantial efficacy of a vaccine candidate against Covid-19 disease, which is very welcome news," she said.
“It is important to bear in mind that these are early results based on a relatively small number of cases. “In addition, the efficacy estimate is based on seven days of follow-up of participants following the second dose; further data in the coming weeks and months will provide a better picture of longer-term vaccine efficacy.”
Need for caution
Dr Michael Head, senior research fellow in global health, University of Southampton, said the results appear “excellent” but he urged caution.
“This cautiously sounds like an excellent result from the phase three trials, but we should remain a little cautious,” he said.
“The provisional findings are made available in a press release and the study is ongoing. However, if the final results show an effectiveness of anywhere near 90% with response in elderly and ethnic minority populations, that is an excellent result for a first generation vaccine.
“This has been seen before – the rapidly-produced Ebola vaccine generated very high levels of effectiveness and exceeded all expectations. Equally, billions of dollars and numerous clinical trials have struggled to produce any form of vaccination against HIV. Science can be unpredictable.”
He added that if the vaccine is approved for use by regulators then there could be difficulties posed by logistics and distribution due to the temperature that the vaccine needs to be stored at.
“If this Pfizer vaccine candidate is licensed, there will be difficulties around logistics and distribution,” Dr Head added.
“It has been reported that the vaccine requires storage at -70 degrees centigrade and that is not necessarily routinely available in most health centres even in the UK, let alone globally.”