Latest trial result for Pfizer-BioNTech Covid vaccine shows 95pc efficacy

18 Nov 2020

Image: © Seda Servet/

While awaiting peer review, the latest phase-three trial result of Pfizer and BioNTech’s Covid-19 vaccine shows it could be up to 95pc effective.

Not long after claiming their Covid-19 vaccine candidate showed an efficacy rate of 90pc, Pfizer and BioNTech said the latest results from the drug’s phase-three trials showed even more promise.

Still awaiting peer review, the companies claim that the vaccine – BNT162b2 – was 95pc effective against Covid-19 beginning 28 days after the first dose. This was based on a small sample size of 170 Covid-19 patients, of which 162 were observed in a placebo group and eight in the vaccine group.

This efficacy rate was consistent across age, gender, race and ethnicity demographics, but was found to be 94pc effective in those aged over 65. The total number of those enrolled in the phase-three study was more than 43,000.

There were 10 severe cases of Covid-19 observed in the trial, with nine of the cases occurring in the placebo group and one in the BNT162b2 vaccinated group. Pfizer and BioNTech said the vaccine should be well tolerated by the wider public with none of the 43,000 study participants showing serious safety concerns.

Side effects

The only severe side effect events greater than or equal to 2pc in frequency after the first or second dose was fatigue at 3.8pc and headache at 2pc following a second dose. Consistent with earlier shared results, older adults tended to report fewer and milder solicited adverse events following vaccination.

As Pfizer and BioNTech have provided the US Food and Drug Administration (FDA) with two months’ worth of trial safety data on at least half of the study’s participants, the companies can now apply for an emergency use authorisation for the vaccine. The FDA states that a coronavirus vaccine must have an effectiveness rate of at least 50pc.

“The study results mark an important step in this historic eight-month journey to bring forward a vaccine capable of helping to end this devastating pandemic,” said Dr Albert Bourla, Pfizer chair and CEO.

“We continue to move at the speed of science to compile all the data collected thus far and share with regulators around the world. With hundreds of thousands of people around the globe infected every day, we urgently need to get a safe and effective vaccine to the world.”

Shipping concerns

Development of this vaccine candidate was announced in March and set out to use RNA to accelerate the production of proteins similar in composition to SARS-CoV2, which could be used to trigger the body’s immune system to fight the actual virus.

Based on their current projections, the companies expect to produce up to 50m vaccine doses globally in 2020 and up to 1.3bn doses by the end of 2021.

As previously reported, a potential challenge to the vaccine’s future distribution – if deemed safe to the public – is its need to be kept in ultra-cold storage at minus 70 degrees Celsius. This would limit the vaccine to being distributed to hospitals and labs, as storing it at a GP’s office would be “very difficult”, according to SVB Leerink analysts.

The companies said they have developed specially designed, temperature-controlled thermal containers that use dry ice to ship the vaccine. The containers can be used be as temporary storage units for 15 days by refilling with dry ice.

Colm Gorey was a senior journalist with Silicon Republic