Quick Answer
The Pfizer-BioNTech COVID-19 vaccine is administered as a series of two doses, given 21 days apart. Each dose is 0.3 mL containing 30 μg of mRNA. So each Pfizer shot contains 0.3 mL of vaccine.
What is the Pfizer COVID-19 vaccine?
The Pfizer-BioNTech COVID-19 vaccine, also known as Comirnaty, is an mRNA-based vaccine developed to prevent coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
The vaccine contains messenger RNA (mRNA) inside lipid nanoparticles. The mRNA provides instructions for cells to make a harmless piece of the spike protein found on the surface of the SARS-CoV-2 virus. This triggers the body’s immune system to recognize the virus and mount an immune response against it.
The Pfizer-BioNTech COVID-19 vaccine requires two doses given 21 days apart to provide full immunity. It is approved for use in individuals 12 years of age and older in many countries around the world.
What is the dosage for each Pfizer shot?
Each dose of the Pfizer-BioNTech COVID-19 vaccine contains 30 micrograms (μg) of mRNA inside 0.3 milliliters (mL) of solution.
So each 0.3 mL Pfizer shot contains 30 μg of mRNA that provides instructions for making the spike protein to trigger an immune response against SARS-CoV-2.
The dosage is the same for both the first and second shots in the two-dose series. Two doses 21 days apart are required to provide the full immune protection offered by the vaccine.
How was the Pfizer dosage determined in clinical trials?
The Phase 1/2 clinical trials conducted by Pfizer-BioNTech evaluated various dosages of their mRNA COVID-19 vaccine to determine the optimal amount needed to provide protection.
They tested 10 μg, 20 μg, and 30 μg doses given 21 days apart and compared the immune response. The results showed:
- 10 μg dose triggered a lower immune response
- 30 μg dose triggered the highest immune response
Based on these findings, the 30 μg dose given 21 days apart was selected to move forward into larger clinical trials.
This dosage continued to show safety and generate a robust immune response in the Phase 2/3 trials involving over 40,000 participants. It ultimately received Emergency Use Authorization and formal approval after meeting high efficacy and safety standards.
What is in the 0.3 mL shot?
Each 0.3 mL dose of the Pfizer COVID-19 vaccine contains the following ingredients:
- 30 μg of mRNA encoding the viral spike (S) protein of SARS-CoV-2
- Lipids (0.43 mg (4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate), 0.05 mg 2[(polyethylene glycol)-2000]-N,N-ditetradecylacetamide, 0.09 mg 1,2-distearoyl-sn-glycero-3-phosphocholine, and 0.2 mg cholesterol)
- 0.01 mg potassium chloride
- 0.01 mg monobasic potassium phosphate
- 0.36 mg sodium chloride
- 0.07 mg dibasic sodium phosphate dihydrate
- 6 mg sucrose
The lipids encapsulate the mRNA to protect it after injection and allow it to enter cells to give instructions for making the spike protein. The other ingredients maintain the pH balance and act as stabilizers for the solution.
Why is the dosage set at 0.3 mL?
There are a few key reasons why each dose of the Pfizer COVID-19 vaccine is set at 0.3 mL containing 30 μg of mRNA:
- Provides the optimal 30 μg dosage of mRNA determined in clinical trials
- Small injection volume is more comfortable for patients
- 0.3 mL can be accurately measured and administered
- Simplifies preparing and giving the correct dosage
- 0.3 mL fits comfortably within the capacity of standard vaccine syringes
The 0.3 mL volume allows easy measurement, withdrawal, and injection of the 30 μg mRNA dosage shown to produce a strong immune response in clinical studies. The small volume also reduces discomfort at the injection site.
Standard syringes and needles used for vaccinations can accurately deliver and hold 0.3 mL. This makes preparing and giving the correct 0.3 mL Pfizer dosage straightforward for healthcare providers.
Are there any alternatives to the 0.3 mL shot?
The approved dosage for the Pfizer COVID-19 vaccine is 0.3 mL containing 30 μg of mRNA and cannot be changed or altered.
There are no alternatives to the 0.3 mL shot for the Pfizer vaccine. The dosage and volume have been carefully selected based on clinical research to provide the demonstrated level of safety and efficacy.
Some other COVID-19 vaccines do come in different dosing volumes, for example:
- Moderna: 0.5 mL per dose
- Johnson & Johnson: 0.5 mL per dose
- AstraZeneca: 0.5 mL per dose
But for the Pfizer-BioNTech vaccine, each shot must be the approved 0.3 mL containing 30 μg of mRNA. Healthcare providers should follow the manufacturer and FDA instructions to ensure patients receive the correct dosing.
Who should get the 0.3 mL dosage?
The 0.3 mL dosage is approved and recommended for all individuals 12 years of age and older who are receiving the Pfizer-BioNTech COVID-19 vaccine.
This includes those getting their first shot or the second booster dose as part of the primary series, as well as those receiving a booster shot after completing the primary series.
The same 0.3 mL dosage is used regardless of the patient’s age, body size, sex, or other factors. The clinical trials supporting the vaccine’s safety and efficacy were conducted using the 0.3 mL dosage for all participants.
Some key groups who should receive 0.3 mL of Pfizer vaccine include:
- Preteens and teens ages 12-17 years
- Adults ages 18 years and older
- Pregnant and breastfeeding women
- People with underlying medical conditions
- Immunocompromised individuals
Unless otherwise advised by the vaccine manufacturer or FDA, the standard 0.3 mL dosage should be used for all eligible recipients 12 years and up.
Are there any exceptions to the 0.3 mL dose?
There are currently no exceptions to using the 0.3 mL dose for those receiving the Pfizer-BioNTech COVID-19 vaccine.
The only group not yet approved to receive the 0.3 mL dosage are children under 12 years old. Pfizer is still conducting clinical trials to evaluate the safety and efficacy of the vaccine in younger children.
Once data is submitted and the FDA grants Emergency Use Authorization, the company will provide guidance on the correct dosage and volume of shots for specific pediatric age groups.
For now, the vaccine is restricted to use in individuals 12 years and older and 0.3 mL containing 30 μg of mRNA remains the only approved dosage for Pfizer COVID-19 vaccination.
Can the dosage be increased beyond 0.3 mL?
No, the dosage should never exceed the approved 0.3 mL volume per Pfizer COVID-19 shot.
Increasing the dosage beyond what is tested and authorized could risk serious side effects and does not provide increased efficacy. The clinical trials determined 0.3 mL containing 30 μg of mRNA provides the optimal immune response in humans.
Here are some key reasons why increasing the Pfizer dosage should be avoided:
- Increases risk of adverse reactions by giving supra-therapeutic doses
- Removes the safety data supporting the approved dosage
- Does not strengthen immune response compared to the 0.3 mL dose
- Goes against the FDA Emergency Use Authorization and guidelines
- Could result in medication errors and incorrect dosing
Healthcare providers must precisely measure and administer 0.3 mL per Pfizer shot. The vaccine is highly effective at this standardized dosage for all recipients.
Is a lower dose ever appropriate?
Administering less than the full 0.3 mL Pfizer COVID-19 vaccine dosage is not recommended and should be avoided, except in certain rare circumstances.
The vaccine dosage should only be lowered under the advice of a healthcare provider in cases where:
- A patient has a known allergy to specific vaccine ingredients – a lowered dose may be tried first to check for allergic reaction before giving the full dose
- The full 0.3 mL dose cannot be withdrawn from a vial – the remaining volume should be administered even if slightly less than 0.3 mL to avoid wasting vaccine
In all other cases, the standard 0.3 mL volume containing 30 μg of mRNA should be given. Partial dosing is not advised and may negatively impact the efficacy of the vaccine.
Patients who receive less than the full 0.3 mL volume should be notified and arrangements made to receive the additional volume to complete the dose. Getting the approved vaccine dosage is important to develop the expected immune protection.
Does the dosage vary between the first and second shot?
No, the dosage does not vary between the first and second dose of the Pfizer COVID-19 vaccine.
Both the first and second shots contain 0.3 mL with 30 μg of mRNA. Two doses of the same volume and dosage are required to complete the primary vaccination series.
The first shot primes the immune system, while the second shot boosts the antibody response. Using the identical 0.3 mL dosage allows the body to mount a robust protective response after the complete course.
There is no need to adjust or change the dosage at different points in the vaccination schedule. The original clinical trials established the correct dosage for each injection as 0.3 mL.
Can children get a lower dose than 0.3 mL?
Currently, the Pfizer COVID-19 vaccine is only authorized for use in individuals ages 12 years and older. The 0.3 mL dosage is proven safe and effective for this age group.
Younger children ages 5-11 years will likely receive a lower dosage once the vaccine is approved for pediatric use. The FDA will grant Emergency Use Authorization for a specific dosage optimized for younger kids based on clinical trial data.
Pfizer’s trials are testing two 10 μg doses given 21 days apart for children under age 12. The dose will be adjusted, but it’s expected the volume will remain 0.3 mL.
The vaccine cannot be administered to younger kids or changed from the approved 0.3 mL dosage until specifically authorized. Parents should wait for a child’s age group to be eligible and receive the properly tested dosage.
Should adults get more than 0.3 mL per dose?
There is no evidence that increasing the 0.3 mL vaccine dosage would provide any additional benefit or improved immune response in adults.
The clinical trials clearly demonstrated the approved dosage generates a robust immune protection against COVID-19 in adult populations.
In fact, higher doses may increase the risk of adverse side effects. The FDA and vaccine manufacturer have determined 0.3 mL containing 30 μg of mRNA is the ideal dosage for adults 18 years and up based on the research data.
Healthcare providers should follow the authorized dosing schedule and never administer more than 0.3 mL volume per dose to adults. Taking more than the recommended amount does not improve efficacy and may decrease safety.
Can the dosage be altered due to health or body size?
The Pfizer COVID-19 vaccine dosage should not be changed from 0.3 mL based on a recipient’s health status or body size.
Clinical trials included adult participants with various underlying medical conditions and weights. The consistent 0.3 mL dosage resulted in a strong immune response and protection across all groups.
Attempting to adjust the dosage carries risks and uncertainty since it deviates from what was directly tested in the research. The authorized 0.3 mL volume is suitable for all eligible adults regardless of their age, gender, comorbidities, and other individual factors.
Providers should stick to the standardized dosage for each recipient, rather than trying to tailor it. The vaccine offers optimal efficacy and safety when given at 0.3 mL as studied and approved.
What if part of the dose leaks out?
The full 0.3 mL dosage of Pfizer COVID-19 vaccine should be administered if any of the dose leaks out after injection.
The needle should be held in place for several seconds after injecting to allow the medication to absorb into the tissue and prevent leakage.
However, if some leakage around the injection site does occur after the needle is removed, the volume lost is generally negligible. The standard dose of 0.3 mL will still have been effectively delivered.
The leakage should simply be cleaned and bandaged without needing to replace the dose. Only if most of the visible volume leaks out should an additional dose be considered, at a minimum interval per vaccination guidelines.
Can the second dose be a different volume?
No, both doses in the 2-shot Pfizer COVID-19 vaccination series should be the same 0.3 mL volume containing 30 μg of mRNA.
The clinical trials did not evaluate using different dosages or volumes between the first and second Pfizer shots. There is no data on the effects of mismatched doses.
To ensure the full efficacy demonstrated in the research, the authorized 0.3 mL dosage must be used for the first shot and matched with an equivalent 0.3 mL second dose 21 days later.
Deviating from the studied dosing regimen risks inadequately priming or boosting the immune response. Both shots are essential at the standardized volume to achieve protection.
Summary
In summary, each dose of the Pfizer-BioNTech COVID-19 vaccine contains 0.3 mL of solution with 30 μg of mRNA inside lipid nanoparticles. Two doses given 21 days apart make up the primary vaccination series.
The 0.3 mL volume per dose was selected based on clinical trial data showing it contains the optimal 30 μg dosage to generate a robust immune response with high efficacy and a favorable safety profile.
All eligible recipients age 12 years and up should receive the approved 0.3 mL dosage per Pfizer shot. Younger children will eventually be eligible for properly tested lower doses. But no adjustments should be made to the volume or dosage for different age groups unless specified by the FDA and manufacturer.
Strict adherence to the authorized 0.3 mL per shot is important to achieve the full benefit of Pfizer vaccination. While rare exceptions exist, providers should generally never give more or less than the standardized dosage and volume that was safely and successfully tested in the research.
