In the final efficacy analysis of the vaccine's phase III trial, following the release of preliminary results on 9 November, the companies say the jab was 95% effective in preventing COVID-19, measured from 7 days after the second dose.
The vaccine's efficacy was consistent between people of different age, gender, race and ethnicity, with over 94% efficacy in adults over 65 years of age.
Pfizer and BioNTech said the vaccine has also met the safety criteria for emergency use authorisation and the data will now be submitted to the FDA and other regulatory agencies around the world. In the UK, the MHRA will be responsible for approving the jab.
Prof Trudie Lang, Director, The Global Health Network, Nuffield Department of Medicine, University of Oxford, said: 'Today’s update from Pfizer provides further encouraging news and more detail on the protection against disease that their vaccine is showing from this definitive phase III trial. The detail on achieving 94% protection in the elderly participants in the trial is particularly excellent news.
'The company are reporting that they now have enough efficacy data to submit for approval from the regulatory authorities, who will undertake a detailed assessment of both the efficacy and safety data. We will need to wait and learn over time how long the protection lasts, and to see whether this vaccine can also prevent transmission – meanwhile, this vaccine does look likely to have a strong role immediately once it is approved in protecting health workers and the vulnerable from disease.'
The final analysis of the vaccine's efficacy is based on 170 cases of COVID-19, only eight of which were in the vaccinated group. Of the 10 severe cases of COVID-19 observed in the trial, one occurred in the vaccine group.
The companies said no serious safety concerns were observed during the trial. The most common adverse events were fatigue, affecting 3.8% of trial participants following the second vaccine dose, and headache, affecting 2% of participants.
The news follows US biotech company Moderna Therapeutics publishing initial results from phase III trials of its vaccine on 16 November, which was shown to be 94.5% effective in preventing COVID-19. The Moderna vaccine uses the same mRNA approach as the Pfizer/BioNTech candidate, but requires only normal refrigeration rather than ultra-cold storage at -70C.
Despite the logistical challenges posed by its storage requirements, the Pfizer/BioNTech vaccine looks likely to be the first COVID-19 vaccine rolled out as part of a UK vaccination programme. The government already has advance orders in place for 40m doses.
Following publication of the first data from its phase III trial on 9 November, England's deputy CMO Professor Jonathan Van Tam said he was hopeful the UK would 'begin to see some vaccine by Christmas'. The companies have said that they expect to produce 50m doses of the vaccine in 2020 and up to 1.3bn by the end of next year.
The government has also placed an initial order for 5m doses of the Moderna vaccine, although it is unlikely these will be available in the UK before spring 2021.