COVID-19 Vaccine Breakthrough: Interim Results From Pfizer Candidate Show It Prevented 90% Of Cases
COVID-19 mRNA vaccine candidate developed by Pfizer and BioNTech.

A COVID-19 vaccine candidate developed by Pfizer and BioNTech has far exceeded expectations, showing a 90% efficacy rate so far among the tens of thousands of volunteers who were immunized in a clinical trial, the company said on Monday.

“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,” said Albert Bourla, CEO of Pfizer, in a press release. 

Albert Bourla, CEO of Pfizer.

In another statement Bourla added: “We are one step closer to potentially providing people around the world with a much-needed breakthrough to help bring an end to this global pandemic.”

In the trial of over 43,000 participants across six countries, there have been 94 cases of COVID-19 in people not previously infected; but fewer than 9 of those cases were in participants who received both shots of the vaccine – leading to the estimate of 90% efficacy for interim trial results, just disclosed.

The trial will continue until 164 cases of COVID-19 are recorded among trial and control arm participants, so as to confirm the efficacy rate. 

Plans are on track for Pfizer and BioNTech to apply to the US Food and Drug Administration (FDA) for an emergency use authorization in the third week of November, Bourla said. 

That will be the milestone moment when a required two months of safety data has been collected for all of those who participated in the trial. No serious safety concerns have been raised so far, the press statements said -although no breakdown by age group has been provided either. Some 42% of participants were from diverse ethnic and racial backgrounds.

The FDA previously said that a COVID-19 vaccine trial should be at least 50 percent effective, which the Pfizer and BioNTech vaccine candidate has far exceeded. 

“The big news is that we have a #SARSCoV2 vaccine with a strong signal of efficacy,” said Eric Topol, founder and director of the Scripps Research Translational Institute, on Twitter. “We’ll have at least one vaccine into Phase 1a rollout before year end, which is a stunning achievement – from virus sequence to vaccination in < 12 months.” 

“This is a victory for innovation, science and a global collaborative effort,” said Ugur Sahin, BioNTech CEO. “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.” 

Avoiding the Election

Pfizer’s announcement narrowly missed the US presidential elections last week  – fulfilling the previous commitment  that the company would not be ready earlier to apply for the authorization. 

Despite the victory of Democratic contender Joe Biden, who has now been recognized as the new President-elect,  US President Donald Trump immediately took to Twitter to trumpet the vaccine breakthrough, saying: 


President-elect Joe Biden took a much more cautious approach, welcoming the progress as “excellent news” giving Ameicans “cause for hope” – but warning that a vaccine would only become widely available later next year. 

“Americans will have to rely on masking, distancing, contact tracing, hand washing, and other measures to keep themselves safe well into next year. Today’s news is great news, but it doesn’t change that fact,” Biden said. 

There had been concern that timing an announcement to coincide with the election might negatively influence public confidence in a vaccine, with Pfizer CEO Albert Bourla criticising President Donald Trump for politicising the vaccine timeline.

Will the Vaccine be Administered Equitably?

Although the results, should they be confirmed, are encouraging news for fighting the pandemic, the Pfizer vaccine, in particular, will pose huge challenges for distribution in low- and middle-income countries because it requires a cold storage temperature in extremes of -70°C. 

Vaccine storage containers being loaded into air cargo. Establishing temperature controlled conditions is essential to respect cold chain requirements.

In addition, there is the question of vaccine supply and distribution. Pfizer and BioNTech estimate that some 50 million vaccine doses could be manufactured by the end of 2020, enough to immunize 25 million people, and 1.3 doses in 2021. They have also said that they are positioned to manufacture more than 1 billion doses during 2021. 

Global health leaders have warned for months that initial vaccine supplies will likely be limited and need to be reserved for healthcare workers and high risk individuals around the world.  

However, Operation Warp Speed, a US government programme aiming to rush a COVID-19 vaccine to market, already signed a $1.95 billion deal with Pfizer for 100 million doses of the vaccine in July. Pfizer also has reached supply agreements with the EU for 200 million doses, covering 100 million people, as well as with the United Kingdom, Canada and Japan. 

If Pfizer’s vaccine is indeed the first to make it to market, the big question that the world will be watching is this: will the company would be obliged to begin distributing all of its initial batches in the USA and other high-income countries where it has already signed procurement deals – with remaining middle- and low-income countries served much later, and after appropriate cold-chain infrastructure is established?   

On the more positive side, the Pfizer vaccine candidate is only one among 10 other vaccine candidates in late-stage clinical trials worldwide. Moderna, a pharma company developing a COVID-19 vaccine with similar technology as Pfizer, has also announced their plans to release their interim clinical results and apply for an FDA Emergency Use Authorization by the end of November. It requires a more moderate – 20°C temperature for shipping and long-term storage.

Science of mRNA Vaccines
Description of Pfizer’s use of mRNA technology to develop COVID-19 vaccines.

Pfizer and BioNTech’s drug is an RNA vaccine. This treatment is based on a part of the virus’ genetic code – messenger RNA (mRNA) – that contains the genetic information needed to produce the coronavirus’ receptors.

If a synthetic mRNA is successfully administered to a person, their cells are then able to build proteins that mimic the receptors, triggering the immune system without causing illness.

The 90% efficacy rate was achieved 7 days after the second dose of the vaccine, which is taken three weeks after the first, totalling 28 days. It has also been shown to block nearly 20 mutated versions of the virus strain, the company said. However the duration of protection obtained remains undetermined. 

Image Credits: Pfizer, World Economic Forum, Flickr – CDC Global, Pfizer.

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