Pfizer’s COVID-19 vaccine is ‘more than 90% effective’; according to Phase 3 interim analysis

By Rachel Arthur contact

- Last updated on GMT

Pfizer and BioNTech have announced success for their COVID-19 vaccine candidate, in the first interim analysis from Phase 3 trials. Pic:getty/jonghoshin
Pfizer and BioNTech have announced success for their COVID-19 vaccine candidate, in the first interim analysis from Phase 3 trials. Pic:getty/jonghoshin

Related tags: Pfizer, COVID-19 vaccine

Pfizer says its COVID-19 vaccine candidate is more than 90% effective in preventing COVID-19, releasing interim analysis from its Phase 3 study this morning. “Today is a great day for science and humanity,” says the company’s CEO.

Both US President-elect Joe Biden and President Donald Trump have welcomed the announcement.

The company says it is on track to submit a request for Emergency Use Authorization (EUA) in the US after the required safety milestone in the third week of November.

What does the interim analysis tell us?

The Phase 3 clinical trial of the Pfizer / BioNTech mRNA based vaccine (BNT162b2) began on July 27 and has enrolled 43,538 participants to date. Of these, 38,955 have received a second dose of the vaccine candidate.

The interim analysis, conducted on November 8 by an external independent Data Monitoring Committee (DMC) is based on the evaluation of 94 confirmed cases of COVID-19 in trial participants.

Timing of interim analysis

Pfizer originally planned to perform the first Phase 3 interim analysis after accrual of 32 cases, with data at the end of October.

However, this analysis was not performed for 'operational reasons,' and after discussion with the FDA, was reset for a minimum of 62 cases. The evaluable case count reached 94 by the time the analysis was carried out.

Another interim analysis is now planned for 120 cases, according to the updated study protocol.

The interim analysis has taken data from 7 days after the second dose of vaccination.

Pfizer says protection is achieved 28 days after the initiation of the vaccination.

The DMC has not reported any serious safety concerns and recommends the study continues as planned. 

'When we embarked on this journey 10 months ago, this is what we aspired to achieve'

Dr. Albert Bourla, Pfizer Chairman and CEO, 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.

"With today’s news, 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.”

With much of Europe facing new restrictions and lockdowns, Germany's BioNTech says the landmark analysis is particularly pertinent.  

“The first interim analysis of our global Phase 3 study provides evidence that a vaccine may effectively prevent COVID-19. This is a victory for innovation, science and a global collaborative effort,”​ said Prof. Ugur Sahin, BioNTech co-founder and CEO.

“When we embarked on this journey 10 months ago this is what we aspired to achieve. Especially today, while we are all in the midst of a second wave and many of us in lockdown, we appreciate even more how important this milestone is on our path towards ending this pandemic and for all of us to regain a sense of normality.

Phase 3 studies

The trial will continue through to its final analysis at 164 confirmed cases to collect further data and characterize the vaccine’s performance against other study endpoints.

The final analysis will now include new secondary endpoints - evaluating efficacy based on cases accruing 14 days after the second dose - as well (the study protocol​ has been updated to reflect these changes).

Participants will also continue to be monitored for long-term protection and safety for a total of two years after their second dose.

Pfizer's Phase 3 trial in the US is set to reach up to 44,000 participants. Other Phase 3 trials are also being carried out at more than 120 clinical sites across the Brazil, South Africa and Argentina. 

Around 42% of global participants and 30% of US participants have racially and ethnically diverse backgrounds.

Based on current projections, Pfizer and BioNTech intend to produce up to 50 million vaccine doses worldwide before the year is out; and up to 1.3 billion doses in 2021.

Pfizer and BioNTech's COVID-19 vaccine candidate: timeline at a glance

Germany’s BioNTech and US-based Pfizer are developing a coronavirus vaccine, BNT162b2, a nucleoside-modified messenger RNA candidate.

The vaccine contains a small part of the genetic code for the SARS-CoV-2 spike protein. By delivering the mRNA to the body's cells, the viral protein is expressed and an immune system response is generated against it.  

March 17:​​ Pfizer and BioNTech announce they will co-develop a potential COVID-19 vaccine, using BioNTech’s mRNA-based vaccine candidate BNT162. The partnership builds on the research and development collaboration into which Pfizer and BioNTech entered into in 2018 to develop mRNA-based vaccines for the prevention of influenza.

July 13:​​ BNT162b2 is granted FDA fast track designation (along with BNT162b1)

July 27​​: BNT162b2 is selected as the lead mRNA vaccine candidate, which starts Phase 2/3 safety and efficacy trials (the program had been assessing four BNT162 RNA vaccine candidates).

Sept 12:​​ Amended protocol submitted to the FDA to expand enrolment of Phase 3 trial to up to 44,000 participants. The Phase 3 trial is being carried out at more than 120 clinical sites across the US, Brazil, South Africa and Argentina.

Sept 18:​​ Pfizer publicly publishes its Phase 3 study protocol

Oct 6:​​ Pfizer and BioNTech initiate rolling submission to European Medicines Agency

November 9:​ ​​Interim analysis (conducted November 8) from phase 3 trial released: showing vaccine is ‘more than 90% effective’

Anticipated third week of November:​ ​​Safety data to support EUA request

Related topics: Bio Developments

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