On the Pfizer/BioNTech Vaccine
Author: Ivana Mišová, PhD.
Published at: 01/12/2021
The year 2021 - the second year of the COVID-19 pandemic - has started on the right foot considering multiple vaccines authorized across many countries, with more surely following soon. While this certainly counts as good news, many are skeptical due to these vaccines’ seemingly fastened development. The first COVID-19 vaccine to receive authorization in “western countries” was developed by Pfizer/BioNTech - what do we know about it? How does it work, and is it truly safe?
What is BNT162b2?
The COVID-19 vaccine developed by Pfizer/BioNTech - BNT162b2 - is an mRNA vaccine. It contains mRNA for SARS-CoV-2 surface spike protein, which is enclosed in a lipid envelope for protection. Once a person is injected with the first dose, the cells make the viral spike protein per mRNA instructions. However, the particles are recognized as foreign by the immune system, and the body starts making antibodies that specifically recognize the viral spike protein1. To obtain the optimal protection the vaccine can offer, each person is injected with two doses 21 days apart2. The second round of vaccinations serves as a booster for our immune system. This ensures that once the real SARS-CoV-2 virus enters our body, our immune system will now recognize the pathogen and be able to fight it, protecting COVID-19 efficiently.
Are mRNA vaccines safe?
While mRNA vaccines have not been used before, it is not due to any safety issues. As they do not use the live virus, they cannot give someone COVID-19. Another misconception is that the mRNA could affect our DNA - the mRNA does not even reach the cell nucleus, where our DNA is stored, so in no way does it interact with our DNA and is degraded soon after the cell produces the spike protein1.
Is the Pfizer/BioNTech vaccine safe and effective?
Data from the Phase 3 clinical study demonstrated a vaccine efficacy rate of 95% in participants without prior SARS-CoV-2 infection. In the trial, BNT162b2 was generally well tolerated with no serious safety concerns3.
Recently, a novel Y501N mutation has emerged, first identified in Britain but spreading quickly across the world. It affects the spike protein of the coronavirus, which raises the question of the effectiveness of vaccines developed to recognize the spike protein (such as the Pfizer/BioNTech vaccine). However, preliminary studies suggest that the Pfizer/BioNTech vaccine can neutralize these mutant versions of the virus4.
Approval and vaccination plans
On December 2, 2020, BNT162b2 was granted a temporary authorization for emergency use against COVID-19 by the Medicines & Healthcare Products Regulatory Agency in the UK5. It was soon followed by conditional authorization in Canada6 and emergency use authorization in the USA7. On December 21, 2020, the BNT162b2 vaccine was granted conditional marketing authorization by the European Commission, making it available for all EU member states under the trade name Comirnaty8. Several other countries, such as Chile, Mexico, Ecuador, Panama, and Costa Rica, have also approved the Pfizer/BioNTech vaccine9. Some have already started vaccinating their citizens - while it is too soon to judge the effectiveness of the vaccine, what can be said is that the vaccine is generally well-tolerated.
Pitfalls of BNT162b2
As this was the first ‘western’ COVID-19 vaccine, massive vaccination campaigns have started in all countries following its approval by the appropriate authorities. However, there are some caveats to this vaccine. One is the strict temperature requirements during shipping and storage - it must be kept at -70°C. Once thawed, it needs to be diluted and used up within 6 hours10. These unusual vaccine storage conditions make the whole logistics of vaccination a bit complicated. Then there is the price per dose, which at 20$ is higher than the cost of most of the competitors’ vaccines11. Finally, there is a crucial issue with equitable distribution (read more here) of the limited number of vaccines available.
Nevertheless, with many countries nearing health system crises due to a record surge in COVID-19 cases, it is high time we had a well-tested, safe, and effective COVID-19 vaccine. With several other vaccines to join the fight against COVID-19, it looks like we finally stand a chance against this pandemic.
- Polack, F. P., Thomas, S. J., Kitchin, N., Absalon, J., Gurtman, A., Lockhart, S., … Gruber, W. C. (2020). Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine. New England Journal of Medicine, 383(27), 2603–2615. https://doi.org/10.1056/NEJMoa2034577
- Neutralization of N501Y mutant SARS-CoV-2 by BNT162b2 vaccine-elicited sera. Xuping Xie, Jing Zou, Camila R. Fontes-Garfias, Hongjie Xia, Kena A. Swanson, Mark Cutler, David Cooper, Vineet D Menachery, Scott D Weaver, Philip R Dormitzer, Pei-Yong Shi. bioRxiv 2021.01.07.425740; doi: https://doi.org/10.1101/2021.01.07.425740