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Pfizer X Biontech Covid-19 Vaccine Primer

Kristiane Polido

The entire world has been waiting with bated breath for a COVID-19 vaccine, and November 9, 2020, Pfizer Inc. and BioNTech SE gave us just that.

In the first interim analysis of their phase 3 study, they reported that the vaccine is 90% effective for healthy individuals that have not contracted COVID-19 before the study.


Having a vaccine with a high percentage of effectivity (90%) gives us all a glimmer of hope. However, it should be clear to the public that it would take several more months before reaching the production stage and a couple more months after that to reach every individual. Unfortunately, that also means that the SARS-CoV 2 virus will take more lives before we can all go back to normal if we ever will. Right now, what we need are good public health measures and protocols for social distancing and navigating through life amid the pandemic.

What’s the big deal?

The big deal is that 90% is a good number. After living through the pandemic for several months, some might even say this number is great. Think of it this way, in a group of 100 people given the vaccine, only 10% can contract the disease. In countries like the Philippines, averaging on 1500 positive cases added every day, this would mean a lot to the healthcare professionals at the forefront of dealing with the virus.

As a point of reference, the flu vaccine is around 40% – 60% effective, while the vaccines for measles and chickenpox are approximately 90% effective. For pharmaceutical companies to develop a vaccine with that high percent of effectivity in just a few months speaks volumes and will save millions of lives when administered globally.

The vaccine in question

The vaccine that Pfizer and BioNTech are developing is an mRNA vaccine. Unlike other conventional methods, an mRNA vaccine does not contain a live virus. What it has is a small part of the genetic code for the spike protein of the SARS-CoV-2. Once the mRNA is delivered to the body’s cells, the viral spike protein will be expressed, and the body will fight it with its natural immune response.

mRNA vaccines are relatively new in vaccine technology since the conventional ones often involve a weakened, dead, or non-infectious part of the virus or bacteria. The mRNA vaccine is different because it contains the genetic material of the virus, which the body will assemble to make the viral protein, and the immune system can recognize. What is similar between the different types of vaccines is their end goal: to train the immune system to identify infectious organisms and build immunity against it by producing antibodies and activating the body’s T-cells.

How are the clinical trials going?

As mentioned above, Pfizer is currently in phase 3 of its clinical trials. Phase 1 started in April 2020, where they evaluated the safety, tolerability, and efficacy of four different mRNA vaccine candidates. At the end of phase 1, they selected the BNT162b2 candidate vaccine, a 30 μg dose level administered in a two-vaccination course.

Phase 3 of the clinical trials started on July 27, 2020, and has an estimated 44,000 participants. This part of the trials is designed to understand if the vaccine is safe and effective against the SARS-CoV-2 virus. According to the interim analysis of Pfizer, the BNT162b2 candidate vaccine is 90% effective.

How sure are we that the vaccine is safe?

Vaccine safety is determined by the safety of the participants during the clinical trials. Ethics committees and regulatory authorities strictly monitor the clinical trials by Pfizer and BioNTech. More so, the clinical trials’ progress is not only monitored by Pfizer scientists; they are also closely monitored by an outside group of experts called the Data Monitoring Committee (DMC). The trial investigators from Pfizer are responsible for monitoring the participants’ health with regular follow-ups as part of the trial.

Pfizer expanded their phase 3 trials to include approximately 44,000 participants, including adolescents as young as 12 years old and people with chronic, stable HIV (Human Immunodeficiency Virus), Hepatitis C, or B infection. By including participants across a wide, diverse background, Pfizer is making sure to understand their candidate vaccine’s safety and efficacy.

Wait a minute, you said ‘interim.’ What does that mean?

Pfizer x BioNTech is not finished yet with the vaccine trials, and they are still in the middle of Phase 3 of the study, hence, the interim analysis. That does not mean that the research is inconclusive or invalid, far from it. The update just tells us that it’s not done just yet, but it’s nearly there. Is it a cause for celebration? Yes, 90% is a good number, and if there were 90% less COVID-19 cases in the world, that’s a win for all of us.

When can we get one?

With promising results, the Pfizer x BioNTech vaccine could be available in very limited quantities by the end of 2020. Pfizer said that they would not apply for the US FDA emergency use authorization until they are finished collecting safety data, sometime around the end of November.

Other pharmaceutical companies are developing a vaccine, and who knows, one of those could be a better one, or one of those can come out even before the Pfizer vaccine. Interim analyses are not official conclusive reports. They are more like an update on how things have been going so far. The other groups working on a vaccine may not publish their interim analyses and follow the usual protocol of telling us if their vaccine is effective or not after the study.

What about the 10%?

The Pfizer x BioNTech vaccine claims to be 90% effective. This number means in the entire group, given the COVID-19 vaccine, it protects 90% of the people, and only the other 10% have the chance of contracting the disease. However, what about the other 10% of the people for whom the vaccine is not effective? Unfortunately, it is too early to say why the vaccine is not effective for them. It would take more extensive studies to know the why’s. In fact, according to their research methodology, the patients for this study by Pfizer and BioNTech would have to be monitored for the next two years.

What does this mean for all of us? It means we are close to a vaccine. It is not yet here, but it is only a matter of time until it is within our reach. It could be ready as early as the end of this year or as late as the middle of 2021, but one thing is for sure: it is on its way.

Reference (Nov-20-A1)

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