Pfizer Covid-19 vaccine '90 per cent more effective in preventing disease' according to study results

The results are based on the first interim analysis of Phase 3 of the study, and evaluated 94 confirmed cases of Covid-19 in trial participants.

The study enrolled 43,538 participants, with 42% having diverse backgrounds, and no serious safety concerns have been observed, the companies report.

They add that safety and additional efficacy data continue to be collected.

The case split between vaccinated individuals and those who received the placebo indicates a vaccine efficacy rate above 90%, at seven days after the second dose.

Researchers say this means that protection is achieved 28 days after the initiation of the vaccination, which consists of two doses.

However, they caution that as the study continues the final vaccine efficacy percentage may vary.

Dr Albert Bourla, Pfizer chairman and chief executive, said: “Today is a great day for science and humanity.

“The first set of results from our Phase 3 Covid-19 vaccine trial provides the initial evidence of our vaccine’s ability to prevent Covid-19.”

He added: “We will continue to collect further data as the trial continues to enrol for a final analysis planned when a total of 164 confirmed Covid-19 cases have accrued.

“I would like to thank everyone who has contributed to make this important achievement possible.”

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.

“The questions around its use were about the ability to manufacture at scale and the possible toxicity associated with a directly injected RNA product.

“The trial data show excellent results in both of those areas, really impressive protection and no reported adverse events.

“The only things we will not know for some time is the longevity of the response in all age groups, but assuming antibody titres are high that should be at least as good as any other vaccine currently in trial.”