Pfizer-BioNTech COVID-19 Vaccine

(BNT162b2 SARS-CoV-2 vaccine)

Pfizer-BioNTech COVID-19 Vaccine

(BNT162b2 SARS-CoV-2 vaccine)
Browsing COVID-19 vaccine clinical trials

Pfizer-BioNTech Vaccine Summary

All information in this page has been gathered from Pfizer's phase 3 clinical trial, unless otherwise referenced.

 

Vaccine Effectiveness

  • 100% effective for prevention of severe COVID-19 illness and death
  • 95% effectiveness in preventing symptomatic COVID-19

Vaccine Safety

  • Most common side effects
    • Injection site: Mild-to-moderate injection site pain
    • General: Fever, fatigue, headache
  • Likelihood of serious side effects were the same as placebo
    • Vaccine group: 0.6%
    • Placebo group: 0.5%
  • Individuals who are allergic to vaccine ingredients (see below) should avoid the Pfizer-BioNTech vaccine

Vaccine Administration

  • 2 intramuscular injections, 3+ weeks apart depending on the population

General Pfizer Vaccine Information

 

What are other names for this vaccine?

COVID-19 vaccines are commonly identified by the name of their manufacturer, who in this case is Pfizer and BioNTech. The scientific name for this vaccine is the BNT162b2 SARS-CoV-2 vaccine.

How does this vaccine work?

Pfizer’s COVID-19 vaccine uses messenger RNA (mRNA). When injected into the body, the vaccine carries instructions for the body’s cells to make one small part of the COVID-19 virus called a spike protein, (not the whole virus). The spike protein alone is harmless. The body’s immune system sees this spike protein as foreign and attacks it. Additionally, the immune system remembers it, so next time there is exposure to the virus, the immune system will react faster and more efficiently to eliminate it and prevent you from developing COVID-19 (especially severe COVID-19).

What are the ingredients?

Ingredient Purpose
Messenger RNA (mRNA) Active component of the vaccine
Fats Protect the mRNA
Salt/buffer Keeps the vaccine at proper pH and makes the vaccine injection more comfortable to receive
Sugar Protects the mRNA during freezing
Water Makes the vaccine an injectable fluid

Notably, Pfizer-BioNTech’s vaccine does NOT contain preservatives, aluminum, or mercury.

How many doses are required?

Pfizer’s COVID-19 vaccine was studied as two intramuscular (injected into the muscle) injections that were given 3 weeks (21 days) apart.

In Canada, the National Advisory Committee on Immunization (NACI) (the expert advisory body to the Public Health Agency of Canada [PHAC]) has advised that second doses of COVID-19 vaccines that require two doses can be administered up to 4 months after the first dose. A single dose of the Pfizer vaccine was still effective in preventing COVID-19, and this decision allows more people in Canada to receive their first dose during the vaccine shortage

What temperature does it need to be stored at?

  • -80 to -60ºC until the expiry dose on the label
  • -20 to -15ºC for up to two weeks, and can be returned to -80 to -60ºC one time
  • 2 to 8ºC for up to 120 hours (five days), i.e. normal refrigerated temperatures
  • Room temperature for up to two hours cumulatively
  • Once reconstituted/mixed with normal saline, it is stable at room temperature or refrigerated for up to six hours

In what types of people has this vaccine been studied?

The Pfizer vaccine was studied in older adolescents and adults ≥ 16 years or older who had not had COVID-19 before. This included both healthy people and those with pre-existing medical conditions.

People who were sick, immunosuppressed, or had unstable pre-existing medical conditions were not included in the original trial, but more data are being gathered as worldwide vaccination increases and more trials are conducted.

Are there any groups of people that this vaccine is NOT recommended for?

The Pfizer vaccine should not be given to:

  • People who are allergic to the active ingredient or to any ingredients in the formulation.
  • People who are hypersensitive (have a severe allergy) to any component of the vaccine
  • People who have a bleeding disorder that would prevent them from having any intramuscular injection

    Is the Pfizer-BioNTech vaccine safe?

     

    What are the side effects and the frequency that they occur?

    The most common side effect is a sore arm at the site of injection. Other common symptoms that might happen include fatigue and headache. People have also been experiencing fever, muscle pain, chills, joint pain, vomiting and diarrhea.

    Will this vaccine make me “sick”? 

    No. The side effects that are experienced after receiving any vaccine, including Pfizer-BioNTech’s Covid-19 vaccine, are caused by the body’s immune system building a response to the virus.

    How do I treat side effects of the vaccine?

    To treat fever/pain, there are over-the-counter pain and fever medications that can be taken. Rest, adequate diet and fluid intake will help as well.

    What are the long-term effects of the vaccine?

    Since this vaccine is so new, it’s impossible to be entirely sure what the long-term effects may be. What we do know is that millions of people have been vaccinated with mRNA vaccines and we have no indication that there are any long-term negative health impacts. People who have received the Pfizer vaccine as part of the Phase 2/3 clinical trial are followed for 2 years after their second dose to continue to monitor for the health effects of the vaccine. In a similar way, governments around the world have reporting systems in place to identify negative health events following vaccines (i.e., the Canadian Adverse Events Following Immunization Surveillance System (CAEFISS)).

    Despite how new these vaccines are, it is important to place the potential vaccine risks within the context of the current pandemic. The known negative health and population impacts of COVID-19 are much greater than the potential negative health impacts of the Moderna vaccine.

    Is the Pfizer-BioNTech vaccine effective for preventing COVID-19?

     

    What does vaccine “efficacy” mean?

    For the Pfizer-BioNTech vaccine, efficacy was measured by how effective the vaccine was in preventing symptomatic COVID-19 infection compared to placebo as measured by the phase 2/3 clinical trial.

    How effective is the Pfizer-BioNTech vaccine? (What is the vaccine’s efficacy?)

    The vaccine was 95% effective in preventing COVID-19 starting one week after the second dose, over the span of a few months. New data will continue to emerge to capture real-world efficacy as well as updates in clinical trials to determine how long this efficacy lasts. Remarkably, those receiving the vaccine had a 0% incidence of death, and only 1 participant in the vaccine group had severe COVID-19 (compared to 11 in the placebo group). Even if the vaccine does not fully protect against a COVID-19 infection, the chance of developing severe illness or dying is significantly reduced.

    How long does this vaccine take before it starts working?

    The vaccine was 95% effective in preventing COVID-19 starting one week after the second dose, over the span of a few months. New data will continue to emerge to capture real-world efficacy as well as updates in clinical trials to determine how long this efficacy lasts. Remarkably, those receiving the vaccine had a 0% incidence of death, and only 1 participant in the vaccine group had severe COVID-19 (compared to 11 in the placebo group). Even if the vaccine does not fully protect against a COVID-19 infection, the chance of developing severe illness or dying is significantly reduced.

    Will the vaccine prevent asymptomatic COVID? Can I still transmit COVID after being vaccinated?

    This was not addressed in the trial; however, data is continuously being collected. Theoretically, there should be a reduction in asymptomatic COVID-19 infection and spread; however, there is still a risk of transmission, and for this reason, social distancing, masks, and limited contacts is still recommended by most authorities.

    Does the vaccine work against COVID-19 variants of concern?

    There may be reduced efficacy against the variants. 

    Three of the main variants of concern are B.1.1.7 (originated in the UK), B.1.351 (originated in South Africa), and P.1 (originated in Brazil.) The vaccines are likely effective against B.1.1.7, and probably less effective against B.1.351. The data on variants is constantly changing and evolving.

    Population-specific recommendations

    The Pfizer vaccine is approved for adults over the age of 16 who are not severely allergic to anything in the vaccine. The clinical trials with published results were designed with adolescents and adults 16 years or older who were not immunocompromised, but may have had conditions such as diabetes, hypertension, etc. Trials for young children and pregnant or breastfeeding people are ongoing.