There are points to be clarified about the Pfizer-BioNTech vaccine


‘onthespot’ reached out to Alessandro Diana pediatrician at the Grangettes-Hirslanden clinic and professor at the Faculty of Medicine and vaccinology unit of the University of Geneva.

There are points to be clarified about the Pfizer-BioNTech vaccine
The logo of the American pharmaceutical company Pfizer. © AP

There are points to be clarified about the Pfizer-BioNTech vaccine

The logo of the American pharmaceutical company Pfizer. © AP

A vaccine that protects 90% from SARS-CoV-2. That’s what Pfizer and BioNTech promise. Lets dig deeper

How should this news be received?

Definitely in a positive way. But it must also be said that it is only a piece of news linked to a press release. Usually the scientific community, before exposing itself, must have data, results in hand. This way of proceeding is unusual, although obviously full of hope. Then it must be emphasized that Pfizer itself has been informed of the preliminary results. In fact, it is an external company that collects data and delivers it to the pharmaceutical company. So, summing up, there are some points that need to be clarified, but the news is undoubtedly positive.

Is it early to sing victory?

A release on positive analyzes does not say everything. Consequently the battle is not won, even if the hope is great. After all, it should be clear in mind that we are in the midst of a global pandemic and any news, negative or positive, regarding a possible cure immediately goes around the world. It happened with the temporary halt of AstraZeneca’s vaccine candidate studies, and it happened with the data shown by Pfizer-BioNTech on Monday. The media interest is enormous, even in this way this particular communication can be read,.

How should the data on protection be interpreted? 90% seems very high?

The vaccine against papilloma virus protects 90%, that against measles - which must be administered in two doses - 95% and more. In vaccinology we can define ourselves happy when a vaccine is around 90% effective. Sometimes you can be satisfied with even 80-85% protection. So Pfizer’s news, from this point of view, is excellent. But still not enough.


The figure of 90% efficacy was recorded 6-7 weeks after the administration of the product on the vaccinated sample. But how effective will it be in another six weeks? And in three months? If the medium-term protection is 30%, then all prospects will change. Conversely, the hopes will be even greater if the rate remains stable. We must therefore wait a little longer, approximately at least until the end of December, to find out more.

Are there any other key points to clarify?

Yes. We still don’t know on which population the vaccine was tested. Are there seniors? Children? People with previous pathologies? Or were only young people in good health taken? Does immunogenicity remain the same in various types of people? If Pfizer’s vaccine candidate works on healthy adults but much less on the elderly, the risk is that the product is of little use. It will in fact be the so-called people at risk who will be vaccinated first. I repeat: the press release is extremely comforting, but it is necessary to have more extensive and detailed data. We need caution.

Let’s dig deeper. There is talk of 44,000 people, half vaccinated and the other not. Are these numbers statistically relevant?

A sample of 20,000 patients is already statistically powerful. And the fact that part of this population is 90% protected is statistically sensitive. The method is therefore correct. But the crux of safety, the so-called safety, remains. What happens to 100,000 patients? And about 500,000? Science, for obvious reasons, works on fewer samples to prove the safety of a product. It will be pharmacovigilance, the control of drugs on the market, which will have to establish safety on much larger samples. These are the so-called phase 4 studies, which can last for years. And it is not excluded that, if there will be side effects on some subjects, that particular vaccine will be called into question.

Is Pfizer-BioNTech’s vaccine already in production?

The two companies have announced that 50 million doses will be available between now and the end of the year. Over one billion at the end of 2021. So I assume so, because pharmaceutical companies - given the global emergency - are willing to take the risk of producing a vaccine on a large scale before they even have the efficacy results. And it is one of the great innovations brought about by the pandemic: incredibly shortening production times. Having a vaccine in 18 months instead of five years is something sensational.

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