“I’m near-ecstatic,” Bill Gruber, one of Pfizer’s senior vaccine scientists, said in an interview. “This is a great day for public health and for the potential to get us all out of the circumstances we’re now in.”
Other scientists tried to marry caution with their obvious excitement at the early results, warning that the full data was not yet available and that the trial was continuing.
“In the absence of any data from Pfizer and BioNTech, we have to take these very exciting claims at face value,” said Dr Simon Clarke, an associate professor of cellular microbiology at the University of Reading. “It seems highly unlikely that a major pharmaceutical company would get such eagerly awaited news wrong.”
Prof Peter Horby of Oxford University, who runs the Recovery Covid drug trial, said it seemed like an important moment.
“This news made me smile from ear to ear,” he said. “It is a relief to see such positive results on this vaccine and bodes well for Covid-19 vaccines in general. Of course we need to see more detail and await the final results, and there is a long, long way to go before vaccines will start to make a real difference, but this feels to me like a watershed moment.”
The company says gathering the required safety data will take until the third week of November. Data from the full trial will be looked at in December. Regulators are already looking at the results and are expected to go through the approval process as fast as is possible, commensurate with safety. Speedy licensing could mean the first doses being available by the end of the year.
There have been concerns that black and minority ethnic populations are particularly vulnerable to Covid. Approximately 42% of global participants and 30% of US participants in the trials have racially and ethnically diverse backgrounds and appear to have been as well – protected as everyone else, the company says. But one important unanswered question is how long the vaccine will last.
Pfizer/BioNTech’s mRNA vaccine, which uses the genetic code rather than any part of the virus itself, has been one of the race leaders. Interim results are also expected this month or in early December from trials for the Oxford University/AstraZeneca vaccine, which is based on a different technology.
The phase 3 trials have involved more than 43,000 people and are intended to establish whether the vaccine works. Volunteers are given either the Covid vaccine, which was administered in two shots about three weeks apart, or a placebo alternative such as the meningitis vaccine, and neither they nor their doctors know which they have had.
The interim analysis looks at how many of those who got infected with Covid-19 had had the new vaccine and how many had the placebo. So far, 94 people have become infected with Covid-19 – this is three times more than the company originally planned, but since the analysis shows that 90% had not received the vaccine, it implies that no more than eight people had received it.
To confirm its efficacy rate, Pfizer said it would continue the trial until there were 164 Covid-19 cases among participants in vaccinated and non-vaccinated groups. Given the recent rise in US infection rates, that number could be reached by early December, Gruber said.
The data is yet to be peer reviewed or published in a medical journal. Pfizer said it would do so once it had results from the entire trial.
To save time, the companies began manufacturing the vaccine before they knew whether it would work. They now expect to produce up to 50m doses, or enough vaccine to protect 25 million people, this year, and up to 1.3bn doses in 2021.
The US and UK both welcomed the development but urged patience.
“I congratulate the brilliant women and men who helped produce this breakthrough and to give us so much cause for hope,” the US president-elect, Joe Biden, said. “It is also important to understand that the end of the battle against Covid-19 is still months away … a mask remains a more potent weapon against the virus than a vaccine. Today’s news does not change this urgent reality.”
A spokesman for the British prime minister, Boris Johnson, said: “The results are promising, and while we’re optimistic of a breakthrough we must remember that there are no guarantees.”
Many countries already have orders for the Pfizer/BioNTech vaccine. The UK has bought 30m doses – enough for 15 million people because two doses are required. The EU has secured 200m doses, which it will distribute. The companies have a $1.95bn (£1.5bn) contract with the US government to deliver 100m vaccine doses beginning this year.
Low-income countries could face problems, however, because the vaccine needs ultra-cold chain; it must be stored at -80C. The BioNTech chief executive, Uğur Şahin, has said his company is researching whether the vaccine might be able to survive for up to five days at a normal fridge temperature of 4C.
In Germany, the government is planning to set up vaccination centres equipped with ultra-low-temperature freezers for the first phase of vaccinations.
Founded in 2008 and based in Mainz, BioNTech employs about 500 scientists. The company, which was set up by Şahin and his wife, Dr Özlem Türeci, as well as the Austrian oncologist Christopher Huber, originally set out to develop new types of immunotherapy for cancer, but has concentrated its capacities on the race for a Covid-19 vaccine.
Even before the first shutdown in the spring, the company had developed 20 candidates for a vaccine and then tested five, of which two showed particularly strong immune reactions.