Pfizer-BioNTech (COMIRNATY) COVID-19 Vaccine Questions

Below are answers to commonly asked clinical questions about Pfizer-BioNTech COVID-19 Vaccine. Get answers to other frequently asked questions:

Vaccination Schedule and Use

The Pfizer-BioNTech COVID-19 Vaccine is authorized under emergency use for people ages 5 through15 years. The Pfizer-BioNTech COVID-19 Vaccine is approved and licensed under the name COMIRNATY for all people ages 16 years and older.

All people for whom vaccination is indicated should receive a primary series of 2 doses 21 days apart. Do not schedule vaccine recipients to receive the second dose earlier than the recommended interval. Additionally,

  • Some immunocompromised people should receive an additional primary dose of Pfizer-BioNTech vaccine at least 28 days after the 2-dose primary series. These people may also receive a booster dose at least 6 months after completing their additional primary (i.e., third) dose of Pfizer-BioNTech vaccine. The booster dose can be Moderna, Pfizer-BioNTech, or Janssen.
  • Some people are eligible to receive a booster dose at least 6 months after the 2-dose primary series. The booster dose can be Moderna, Pfizer-BioNTech, or Janssen.

Learn more about the COVID-19 vaccine schedule and who is recommended to receive an additional primary dose or booster dose.

Yes. Second doses or additional primary doses of Pfizer-BioNTech COVID-19 Vaccine administered up to 4 days before the recommended date (4-day grace period) are considered valid. This means that the following are considered valid:

  • A second dose administered 17 or more days after the first dose
  • An additional primary dose administered 24 or more days after completion of the primary series (for moderately to severely immunocompromised people)

If a dose is inadvertently administered before the 4-day grace period, it should be repeated.

  • A second dose administered 16 or fewer days after the first dose should be repeated
  • An additional primary dose administered 23 or fewer days after completion of the primary series should be repeated

This is considered a vaccine administration error. Determine how the error occurred and implement strategies to prevent it from happening again. Additionally, you are required to report COVID-19 vaccine administration errors to the Vaccine Adverse Event Reporting System (VAERSexternal icon).

No. The grace period cannot be used to schedule second doses. Administer doses as close to the 21-day interval as possible, but not earlier than recommended. The grace period should be used only for retrospectively reviewing records. If it is discovered a dose has been inadvertently administered within a grace period of 4 days before the recommended date for the second dose (i.e., 17–20 days after the first dose), the dose is considered valid.

No. You should administer the second dose as close as possible to the recommended interval of 21 days after the first dose. However, if the second dose is administered after this interval, there is no need to restart the series.

All doses of the primary series and the additional primary dose should be completed with the same product. Make every effort to determine which vaccine product was administered as the first dose to ensure your patient completes the vaccine series with the same product. In exceptional situations, when the vaccine product given for the first dose cannot be determined or is no longer available, you may administer any available mRNA COVID-19 vaccine, with a minimum of 28 days between doses.

  • If a patient received the first dose of an mRNA COVID-19 vaccine but is unable to complete the series with either the same or a different mRNA COVID-19 vaccine (e.g., due to contraindication), you may consider administering a single dose of Janssen COVID-19 Vaccine, with a minimum of 28 days between doses. See contraindications and precautions for more information on use of Janssen COVID-19 Vaccine and additional precautions in people with a contraindication to mRNA COVID-19 vaccines.

No. When the same mRNA vaccine product is temporarily unavailable, it is preferable to delay the second dose to administer the same product rather than administer a mixed series using a different product.

Learn more about interchangeability of COVID-19 vaccine products.

Yes. You may administer a COVID-19 vaccine before, at the same visit, or after other vaccines without regard to timing(including live, attenuated vaccines). If a patient is due for more than one vaccine, providers are encouraged to offer all of the vaccines at the same visit. Coadministration of all recommended vaccines is important because it increases the probability that people will be fully vaccinated. It is also an important part of immunization practice if a healthcare provider is uncertain that a patient will return for additional doses of vaccine.

Learn more about coadministration with other vaccines.

Booster Doses

The following recipients of an mRNA primary series should receive a single booster dose at least 6 months after completing the primary vaccine series:

People in the following groups may receive a booster dose at least 6 months after completing their primary vaccine series, based on their individual benefits and risks:

All other people 18 years of age and older, based on their individual risks and benefits. Learn more about considerations for COVID-19 vaccine booster doses.

Yes. The 4-day grace period applies to the booster dose. A booster dose of Pfizer-BioNTech COVID-19 Vaccine administered up to 4 days before the recommended date (4-day grace period) is considered valid. Use the grace period when retrospectively reviewing records to determine the validity of a dose. Do not use the grace period to schedule doses.

If a booster dose is administered than the grace period (i.e., 4 days before the 6-month interval from the primary series), do not repeat the dose. This is considered a vaccine administration error. Determine how the error occurred and implement strategies to prevent it from happening again. Additionally, you are required to report COVID-19 vaccine administration errors to the Vaccine Adverse Event Reporting Systemexternal icon.

The dosage for the Pfizer-BioNTech COVID-19 booster dose is 0.3 mL, which is identical to the dosage for the 2-dose primary series.

For groups recommended to receive a booster, people have the option to receive any of the FDA-approved or FDA-authorized COVID-19 booster products (Pfizer-BioNTech, Moderna [half dose] or Janssen). Discuss the risks and benefits and which product may be most appropriate with individual patients.

Clinical trial data using homologous or heterologous (“mix and match”) boosters show that both increase immune response.

The risks of different FDA-approved or FDA-authorized vaccines after a booster dose are similar to those experienced after a primary series, which includes:

  • The rare risk of myocarditis and pericarditis (the group at highest risk is males younger than 30 years of age)
  • The rare risk of Guillain-Barre Syndrome (the group at highest risk is males ages 50–64 years)
  • The rare risk of thrombosis with thrombocytopenia syndrome (TTS) after a Janssen COVID-19 booster dose. Women ages 18–49 should be made aware of the increased risk for TTS and the availability of mRNA COVID-19 vaccines for a booster dose. People who developed TTS after their initial Janssen vaccines should not receive a Janssen booster dose.

Learn more about considerations for selecting which booster dose to receive.

For groups recommended to receive a booster, people have the option to receive any of the FDA-approved or FDA-authorized COVID-19 booster products (Pfizer-BioNTech, Moderna [half dose] or Janssen). This applies even if a patient received a mixed 2-dose mRNA primary vaccine series.

Learn more about considerations for selecting which booster dose to receive.

People with moderate or severe immune compromise who received an mRNA COVID-19 vaccine primary series should receive an additional dose of the same mRNA vaccine completed for the primary series 28 days after the completion of a primary series

These people should receive a booster dose at least 6 months after completing their additional primary dose if they are:

  • 50 years of age and older
  • Residents 18 years of age and older in long-term care settings

All other moderately or severely immunocompromised people 18 years of age and older may receive a booster at least 6 months after completing their additional primary dose.

The booster dose can be any FDA-approved or FDA-authorized COVID-19 vaccine, even if it is a different product than the primary series.

If a booster dose is given at any time earlier than the recommended interval (i.e., earlier than 6 months after completion of the mRNA primary series), do not repeat the dose.

This is considered a vaccine administration error. Determine how the error occurred and implement strategies to prevent it from happening again. Additionally, you are required to report COVID-19 vaccine administration errors to the Vaccine Adverse Event Reporting Systemexternal icon.

Yes. Eligible people that experience COVID-19 after being fully vaccinated can receive a booster dose. People with known current SARS-CoV-2 infection should defer vaccination at least until they have recovered from the acute illness (if they had symptoms) and have met criteria to discontinue isolation. Current evidence about the optimal timing between SARS-CoV-2 infection and vaccination is insufficient to inform guidance.

People vaccinated with an FDA-approved or FDA-authorized COVID-19 vaccine outside the United States: Should follow guidance for booster doses as detailed in Considerations for use of a COVID-19 booster dose.

People who completed all of the recommended doses of a World Health Organization Emergency Use Listing (WHO-EUL) COVID-19 vaccine not FDA-approved or FDA-authorized , or people who completed a heterologous (mix and match) series composed of any combination of FDA-approved, FDA-authorized, or WHO-EUL COVID-19 vaccines: Are eligible to receive a single booster dose of Pfizer-BioNTech COVID-19 Vaccine at least 6 months after completing the primary series, if at least 18 years of age.

People who received only the first dose of a multidose WHO-EUL COVID-19 primary series that is not FDA-approved or FDA-authorized, or who received all or some of the recommended doses of a COVID-19 vaccine primary series that is not listed for emergency use by WHO: Should be offered primary vaccination with an FDA-approved or FDA-authorized COVID-19 vaccine. After completion of primary series, are considered fully vaccinated, and are not recommended to receive an additional primary or booster dose at this time.

For more information, see:

Vaccine Indications, Contraindications, and Precautions

Most people can receive a COVID-19 vaccine; however, there are some situations in which CDC recommends deferring vaccination. See COVID-19 Vaccine FAQs for Healthcare Professionals: Vaccine Indications for more information.

Pfizer-BioNTech COVID-19 Vaccine and Risk of Myocarditis/Pericarditis

Myocarditis is inflammation of the heart muscle, and pericarditis is inflammation of the outer lining of the heart. In both cases, the body’s immune system causes inflammation in response to an infection or some other trigger. Symptoms can include chest pain, shortness of breath, or palpitations.

The severity of cases of myocarditis and pericarditis can vary. For the cases reported after mRNA COVID-19 vaccination, most who presented to medical care have responded well to medications and rest.

The ACIP COVID-19 Vaccines Work Group reviewed:

  • Clinical trial and post-authorization safety data for myocarditis/pericarditis after receipt of mRNA COVID-19 vaccines
  • A risk-benefit assessment of myocarditis/pericarditis after receipt of mRNA COVID-19 vaccines

On June 23, 2021, after reviewing available evidence, ACIP determined that the benefits of using mRNA COVID-19 vaccines clearly outweigh the risks of myocarditis in all populations, including adolescents and young adults.

For more information see: Use of mRNA COVID-19 Vaccine After Reports of Myocarditis Among Vaccine Recipients: Update from the Advisory Committee on Immunization Practices — United States, June 2021

Yes. People who have a history of myocarditis or pericarditis unrelated to mRNA COVID-19 vaccination may receive any FDA-authorized or approved COVID-19 vaccine after the episode of myocarditis or pericarditis has completely resolved. This includes resolution of symptoms attributed to myocarditis or pericarditis, as well as no evidence of ongoing heart inflammation or sequelae as determined by the person’s clinical team, which may include a cardiologist, and special testing to assess cardiac recovery.

A person is considered fully vaccinated against COVID-19 2 or more weeks after receipt of the second dose in a 2-dose series (Pfizer-BioNTech and Moderna) or 2 or more weeks after receipt of the single dose of the Janssen vaccine. A person who only receives one dose of a 2-dose mRNA COVID-19 vaccine series is not considered fully vaccinated.

It is unclear if people who developed myocarditis or pericarditis after a first dose of an mRNA COVID-19 vaccine may be at increased risk of further adverse cardiac effects following a second dose of the vaccine. Until additional safety data are available, experts advise that people who develop myocarditis or pericarditis after a first dose of an mRNA COVID-19 vaccine not receive a subsequent dose of any COVID-19 vaccine. People with a history of myocarditis or pericarditis who choose to receive a subsequent dose of an mRNA COVID-19 vaccine should wait at least until their initial episode of myocarditis or pericarditis has completely resolved. Decisions about proceeding with the second dose of an mRNA vaccine should include a conversation between the patient, their parent, guardian, or caregiver (when relevant), and their clinical team.

Although myocarditis or pericarditis after mRNA COVID-19 vaccination can occur in both men and women, more cases have been reported in men in younger age groups. Consider myocarditis and pericarditis in adolescents or young adults with acute chest pain, shortness of breath, or palpitations. Ask about prior COVID-19 vaccination if you identify these symptoms, as well as relevant other medical, travel, and social history. For more information, please refer to Myocarditis and Pericarditis Following mRNA COVID-19 Vaccination.

Based on data from VAERS, confirmed cases have typically occurred within several days after COVID-19 vaccination.

Vaccine Storage and Handling

Storage recommendations are based on formulation.

The 5 through 11 years of age formulation (orange cap) may be stored in:

  1. Ultra-cold freezer between -90°C and -60°C (-130°F and -76°F) up to the expiration date. Keep vaccine vials upright and in their tray and protect from light.
  2. Refrigerator between 2°C and 8°C (36°F and 46°F) for up to 10 weeks.

Do NOT store the 5 through 11 years of age formulation in the freezer or thermal shipping container.

The 12 years of age and older formulation (purple cap) may be stored in:

  1. Ultra-cold freezer between -90°C and -60°C (-130°F and -76°F) up to the expiration date. Keep vaccine vials upright and in their tray and protect from light.
  2. Thermal shipping container using the Controlant temperature monitoring device (TMD) temporarily. Maintain the appropriate temperature by adding dry ice to the shipping container according to the manufacturer’s guidance. Keep vaccine vials upright and in their tray and protect from light.
  3. Freezer between -25°C and -15°C (-13°F and 5°F) for up to 2 weeks. Keep vaccine vials upright and in their tray and protect from light.
  4. Refrigerator between 2°C and 8°C (36°F and 46°F) for up to 31 days.

For more detailed information on storage, see:

Contact the manufacturer about deviations from standard storage as described in the Fact Sheet for Healthcare Providersexternal icon.  Let them know how long vaccine was stored at which temperature(s) so a determination can be made as to whether doses have been compromised. If the manufacturer does not have data to support the stability of the vaccine, repeat the dose immediately (no minimum interval).

This is considered a vaccine administration error. Determine how the error occurred and implement strategies to prevent it from happening again. Additionally, you are required to report COVID-19 vaccine administration errors to the Vaccine Adverse Event Reporting System.

Determining the expiration date is different for each formulation.

  • 5 through 11 years of age formulation (orange cap): Vaccine expires 6 months after the manufacture date.
    • The manufacture date is printed on the vial.
    • Count out 6 months, using the month printed on the vial as month 1.
    • The vaccine expires on the last day of the 6th month.
    • For examples, if the date printed on the vial is 08/2021, month 1 is August 2021. Month 6 is January 2022. The vial expires January 31, 2022.
  • 12 years of age and older formulation (purple cap): Vaccine expires on the date printed on the vaccine vial.

For both formulations, as the expiration date approaches, contact the manufacturer to determine if it has been extended. Do not discard vaccine without ensuring the expiration date has passed.

Expired vaccine should NEVER be administered. To prevent this, use CDC’s COVID-19 Vaccine Expiration Date Tracking Toolpdf icon.

For more detailed information on storage, see:

Because of the ultra-cold storage requirements, the manufacturer recommends that you not open the vial tray and inspect individual vials. Rather, keep the trays closed and inspect only the outside of the package and trays. You may inspect vials when you are ready to thaw and use the vaccine.

If you have concerns about the condition of the package, contact the manufacturer.

See Pfizer-BioNTech COVID-19 Vaccine Storage and Handling Summarypdf icon for more storage and handling information.

If temporarily storing vaccine in the thermal shipping container (12 years of age and older formulation [purple cap] ONLY), determine the number of vials/doses needed before opening the shipping container. Open the thermal shipping container no more than twice per day for no more than 3 minutes each time. Use vaccine vials stored in the refrigerator before removing additional vials from frozen storage.

The 5 through 11 years of age formulation (orange cap) CANNOT be stored in the thermal shipping container.

See Pfizer-BioNTech COVID-19 Vaccine Storage and Handling Summarypdf icon for more storage and handling information.

An expiration date is a date, usually defined by the manufacturer, after which a product should not be used. In certain circumstances, usually determined by the manufacturer, an expiration date can be extended.

A beyond-use-date (BUD), by contrast, is a date/time that is generated when a product is transitioned between storage states (e.g., ultra-cold, freezer, refrigerator, room-temperature), when a product vial is punctured, or when some other transition occurs.  It is a new deadline after which the product should not be used.  This new deadline replaces but will never extend beyond the expiration date. When moving vaccine from one type of storage to another, puncturing a vial for use, and mixing vaccine with diluent, always label the vial with the BUD and staff initials.

Resources:

 

 

Beyond-use date recommendations are based on formulation.

Track beyond-use dates for the 5 through 11 years of age formulation (orange cap):

  • Before mixing, vaccine may be stored in the refrigerator between 2°C and 8°C (36°F and 46°F) for up to 10 weeks. After 10 weeks, contact the manufacturer for guidance before discarding any vials.
  • Once mixed, vaccine must be discarded within 12 hours. Note: Some labels on the orange cap formulation may state “Discard 6 hours after dilution.” The information in the Fact Sheet for Healthcare Providersexternal icon supersedes the information on the label. The 12-hour beyond-use date is correct.

Track beyond-use dates for the 12 years of age and older formulation (purple cap):

  • Before mixing, vaccine may be stored in the refrigerator between 2°C and 8°C (36°F and 46°F) for up to 31 days. After 31 days, contact the manufacturer for guidance before discarding any vials.
  • Before mixing, vaccine may be stored in the freezer between -25°C and -15°C (-13°F to 5°F) for up to 2 weeks.
  • Once mixed, vaccine must be discarded within 6 hours.

Resources:

No. The beyond-use date replaces but never extends a manufacturer’s expiration date. In this case, 10 weeks would exceed the expiration of 1/31/22. As expiration date approaches, contact the manufacturer to determine if it has been extended. Do not discard vaccine without ensuring the expiration date has passed.

Yes. After the 2-week time frame, you have two options:

  • You may transfer vaccine to refrigerated storage between 2°C and 8°C (36°F and 46°F) for up to 31 days. After 31 days, contact the manufacturer for guidance.
  • You may return vaccine one time to ultra-cold temperature storage (-80°C to -60°C [-112°F to -76°F]).

See Pfizer-BioNTech COVID-19 Vaccine Storage and Handling Summarypdf icon for more storage and handling information.

If using an ultra-cold freezer, freezer, or refrigerator to store vaccine:

CDC requires vaccination providers participating in the COVID-19 Vaccination Program to use a specific type of TMD called a “digital data logger” (DDL) to monitor vaccine temperatures. A DDL provides the most accurate storage unit temperature information, including details on how long a unit has been operating outside the recommended temperature range (referred to as a “temperature excursion”). DDLs using a buffered temperature probe provide the most accurate way to measure actual vaccine temperatures. Always use DDLs with a current and valid Certificate of Calibration Testing.

Not all DDLs are designed to register or measure ultra-cold temperatures. Check with the DDL manufacturer to verify your DDL can measure ultra-cold temperatures. Additionally, many DDL manufacturers use pure propylene glycol (freezing point -59°C) or a glycol mixture with a warmer freezing point. For accurate ultra-cold temperature monitoring, it is essential to use an air-probe or a probe designed specifically for ultra-cold temperatures with the DDL.

If using the thermal shipping container to store vaccine the 12 years of age and older formulation (purple cap)

Use the Controlant TMD included with the shipping container.

For more storage and handling information, see:

Yes, if vials are thawed at room temperature, the 30-minute thawing time is included in the 12-hour time limit.

Vials can be at room temperature a total of 24 hours, provided the time limit before and after dilution is not exceeded:

  • Before dilution, vials can be stored between 8°C and 25°C (46°C and 77°C), including thawing time, for a maximum of 12 hours.
  • After dilution, vials can be stored between 2°C and 25°C (36°C and 77°C). Vials should be discarded 12 hours after dilution.

See the Fact Sheet for Healthcare Providers Administering Vaccineexternal icon for this formulation.

After dilution, vials must be stored between 2°C and 25°C and used within:

  • 6 hours of dilution for vials of 12 years of age and older formulation (purple cap)
  • 12 hours of dilution for vials of 5 through 11 years of age formulation (orange cap)

Discard any remaining vaccine after this time according to your state immunization program’s directions for proper disposal.

If the vaccine experienced problems during shipment (for example, damage or temperature excursion), contact

Pfizer at 800-666-7248 (option 8) or CVGovernment@Pfizer.com.

If the vaccine experienced problems after it was received and placed into storage, contact the vaccine manufacturer for guidance on improper storage and handling.

For temperature excursions (out-of-range temperatures), take immediate action:

  • Label the vaccine “Do Not Use” and store at the recommended temperature range until you receive manufacturer guidance.
  • Document the date and length of time of the excursion, storage unit temperature, room temperature, and inventory affected.
  • Record any other relevant information.
  • Contact the manufacturer for guidance on whether to use affected vaccines and whether patients need to be recalled for revaccination.
  • If advised to dispose of the vaccine, properly dispose of the vaccine as biohazard waste. Never return vaccines with thermal shipping containers back to the manufacturer.
  • Document the event and action taken for record-keeping requirements.

Recommendations for transporting vaccine in a syringe are based on formulation.

For both formulations, CDC recommends transporting vaccine in vials.

COVID-19 Vaccine Handling Guides: Operational Considerations for Healthcare Practitionersexternal icon

Vaccine Administration

The Pfizer-BioNTech COVID-19 vaccine is concentrated and must be mixed with 0.9% sodium chloride (normal saline, preservative-free) before administering to a patient. Mix with

  • 1.3 mL diluent for the 5 through 11 years of age formulation (orange cap)
  • 1.8 mL diluent for the 12 years of age and older formulation (purple cap)

This diluent will arrive separately from the vaccine in an ancillary supply kit. NEVER use bacteriostatic normal saline or any other diluent. CDC has developed an infographicpdf icon that can be posted in medication preparation areas as a reference.

Diluent is supplied in single-use vials. You must mix the vaccine using a NEW vial of diluent and a NEW vial of vaccine EVERY TIME. Discard the diluent vial after mixing the vaccine. Because 0.9% sodium chloride (normal saline) is preservative-free, it is important to enter the vial only once. Inserting the needle twice could provide a direct route for microorganisms to enter the vial and contaminate the fluid in these devices. By entering the vial only once you will prevent inadvertent contamination of the vial that could lead to infection transmission. See Questions about Single-Dose/Single-Use Vials for more information.

See Pfizer-BioNTech COVID-19 Vaccine Preparation and Administration Summarypdf icon and Preparation Infographicpdf icon for more information.

After dilution, each multidose vial of Pfizer-BioNTech COVID-19 Vaccine contains

  • Six 0.3 mL doses for the 12 years of age and older formulation (purple cap)
  • Ten 0.2 mL doses for the 5 through 11 years of age formulation (orange cap)

The amount of excess vaccine left in the vial can vary based on provider technique and ancillary supplies. Always follow these practices when extracting the final dose:

  • Extract the proper dose. Each dose MUST be the authorized or approved dosage of vaccine outlined in the Fact Sheet for Healthcare Providersexternal icon, regardless of whether it is intended for an adult, adolescent (ages 12 through 17), or child (ages 5 through 11) recipient. There is no weight-based dosing for the Pfizer-BioNTech COVID-19 Vaccine.
  • Do NOT combine remaining vaccine from multiple vials to obtain a full dose.
  • If the amount of vaccine remaining in the vial cannot provide a full dose, discard the vial and contents.

See Pfizer-BioNTech COVID-19 Vaccine Preparation infographicpdf icon to learn more about withdrawing all doses.

Vaccine dosages are based on age and not size or weight because they work differently than other medications. This is true for COVID-19 vaccines as well as other routinely recommended vaccines, like influenza or hepatitis vaccines.

Medications are often based on weight because they are distributed through the bloodstream and work when a certain medication level is present. In this case, a person’s weight is important for the dosage. A person weighing more will require more of a medication to achieve the same effects that than a person weighing less would require.

Vaccines work differently and are not distributed through the bloodstream. Vaccines imitate an infection when administered, activating the body’s immune response, which typically occurs at or near the injection site. Immune cells (antigen-presenting cells) are directed to the injection site to attack foreign cells and produce antibodies and memory cells that will protect against future infection. The immune response generates memory cells and antibodies that travel throughout the body and will recognize the virus in the future.

Because of how vaccines work, they typically require low quantities of active ingredients. Different dosages are evaluated during vaccine development to determine the lowest effective dose for the target age group. Clinical trials evaluate various dosing regimens to determine the best dosage and schedule that produces an adequate immune response which is both safe and effective.

Learn more about:

Understanding How Vaccines Work

CDC recommends that children receive the vaccine dosage and formulation based on their age on the day of vaccination for each dose. If a child turns 12 years old between their first and second dose, administer a:

  • 0.2mL dose of the 5 through 11 years of age and older formulation (orange cap) for the first dose (when they are 11 years old)
  • 0.3mL dose of the 12 years of age and older formulation (purple cap) for the second dose 21 days after the first dose (when they are 12 years old)

However, the FDA authorizationexternal icon allows children who will turn from 11 years to 12 years of age between their first and second dose in the primary series to receive the authorized dosage of either formulation for either dose. If such dosing occurs, the child is considered fully vaccinated. This is not considered an error and should not be reported to VAERS.

No. Preferences for a higher dosage or the same formulation are not reasons to delay vaccination. This leaves a child unprotected from COVID-19 longer than necessary. Clinical trials evaluate various dosing regimens to determine the best dosage and schedule that is both safe and effective in each age group. CDC recommends that children receive the vaccine dosage and formulation based on their age on the day of vaccination for each dose, even if this means they might receive a lower dosage or different formulation for each primary series dose.

Vaccine recipients should receive the correct vaccine formulation for their age. If the orange cap formulation is administered to a person

  • Aged 12 through 17 years old: Do NOT repeat the dose. If the dose given in error is the first dose, administer an age-appropriate dose 21 days after the dose given in error to complete the primary series.
    • As an exception, providers may use clinical judgement about the individual situation and repeat a dose of the age-appropriate formulation (12 years of age and older formulation; purple cap) at an interval of 21 days after the dose given in error. For example, a provider may choose to repeat one dose with the age-appropriate formulation if an adolescent 12 years old or older receives two primary series doses of the orange cap formulation.
  • Aged 18 years and older: Repeat dose immediately. If the dose given in error is the first dose, administer another age-appropriate dose 21 days after the repeat dose to complete the primary series.

This is considered a vaccine administration error if the recipient is 13 years old or older. Providers are required to report COVID-19 vaccine administration errors to VAERSexternal icon. For more information, see Appendix A.

No, you cannot use the 12 years of age and older formulation (purple cap) to vaccinate a child between 5 through 11 years of age, even if it is one third of the purple cap dose. Although it might appear that one third of the purple cap formulation (0.1 mL) would be equivalent to a 10ug concentration of mRNA per dose, the correct concentration of mRNA cannot be guaranteed in such a small volume of vaccine.

Pfizer recommends the use of a syringe with appropriate graduations to dilute with the directed 1.3 mL of saline for the 5 through11 years of age formulation. The impact to the final dose with a 1.2 mL or 1.4 mL dilution volume would be within 4% of the target dose. This suggests that using a syringe with 0.2 mL graduations and estimating the 1.3 mL volume will not significantly impact the intended dose.

Some ancillary supplies kits contain 100-unit (1 mL) insulin syringes to administer COVID-19 vaccine. Only 100-unit (U-100) insulin syringes will be included in the kits. If you have received insulin syringes in COVID-19 ancillary supplies, ensure staff is knowledgeable regarding how they should be used, including measuring the correct dosage (volume) of vaccine. Best practice considerations include:

  • One unit of U-100 insulin measures 0.01 mL in a U-100 units/1 mL syringe, therefore, 10 units of a U-100 insulin measures 0.1 mL in a U-100 units/1 mL syringe.
    • 5 through 11 years of age formulation (orange cap): 0.2 mL dosage = 20 units
    • 12 years of age and older formulation (purple cap): 0.3 mL dosage = 30 units
  • Attach the correct needle length and gaugepdf icon based on the vaccine recipient. The needle length is determined by the administration route, injection site, and recipient’s age. Gender and weight are additional considerations for people 19 years of age and older.

CDC recommends healthcare providers follow the dosing guidance from the manufacturer as outlined in the Fact Sheet for Healthcare Providers Administering Vaccineexternal icon. CDC will update its guidance if the EUA or approval and ancillary supply kits support obtaining additional doses per vial in the future.

Low dead-volume syringes and/or needles can help you withdraw the number of doses outlined in the EUA.

To maximize the number of vaccine doses, use a combination of low dead-volume syringes and/or needles for each vial as follows:

  • Avoid extracting an entire vial with all low dead-volume syringes. This will leave you with too few low dead-volume syringes as you near the end of your ancillary supplies, and you may not be able to withdraw all doses.
  • Do not prioritize using low dead-volume products over selecting the proper needle gauge and lengthpdf icon for vaccine recipients.

See Pfizer-BioNTech COVID-19 Vaccine Preparation infographicpdf icon to learn more about withdrawing all doses.

See USP’s FAQ for Maximizing COVID-19 Vaccine Dosespdf iconexternal icon to identify specific low dead-volume products from ancillary supply kits.

Contact the manufacturer. mRNA vaccine is very fragile and should not be shaken. Vials should only be gently inverted.

Some interim recommendations for COVID-19 vaccine administration errors differ from ACIP’s General Best Practice Guidelines. Review vaccine administration errors and deviations for COVID-19 vaccines to learn about the interim recommendation for each type of error.

For all vaccine administration errors:

Vaccine Safety and Efficacy

Before vaccination, counsel patients about expected local and systemic side effects.

Common side effects include:

Local reactions:

  • Pain
  • Redness
  • Swelling

Systemic reactions:

  • Tiredness
  • Headache
  • Muscle pain
  • Chills
  • Fever
  • Nausea

Clinical trial data demonstrated vaccine efficacy against symptomatic, laboratory-confirmed COVID-19 following receipt of 2 doses of Pfizer-BioNTech COVID-19 Vaccine was:

  • 95% in people age 16 years and older
  • 100% in adolescents age 12–15 years old
  • 90.9% in children age 5–11 years old

Learn more about COVID-19 Vaccine Effectiveness.

For adults, adolescents, and children, both doses are necessary for developing the most protection. Effectiveness of a single dose has been studied in phase III trials and some observational studies. Different studies have demonstrated different rates of effectiveness, but all have been lower than the effectiveness after 2 doses. Additionally, the duration of protection from a single dose is unknown.

Learn more about vaccine effectiveness of a single dose.

Vaccination of Minors

The federal government does not have specific requirements for medical consent for vaccination. States/jurisdictions have medical consent laws that address the circumstances under which a medical provider must seek consent prior to a medical procedure and the processes for obtaining that consent. These laws vary across jurisdictions. Providers may also be subject to policy requirements for consent within their own organizations.

To access COVID-19 vaccine in the United States, a provider must enroll in the Centers for Disease Control and Prevention (CDC) COVID-19 Vaccination Program and sign the applicable CDC Provider Agreement. The CDC COVID-19 Vaccination Program Provider Agreement requires the provider to comply with applicable patient assent and consent laws in their state/jurisdiction for administration of COVID-19 vaccines.

Some state, tribal, and territorial laws may require a parent or legal guardian to accompany an eligible minor to receive vaccinations. Some jurisdictions’ laws may allow parent/guardian consent without a requirement to be physically present for the vaccination if the provider is given evidence of the consent prior to vaccination. Providers may also have to comply with policy requirements determined by their organizations.

No, in-person provision of the Fact Sheet is not a federal requirement. Under the CDC COVID-19 Vaccination Program Provider Agreement, the vaccine provider may provide the Fact Sheet to the parent or legal guardian prior to the visit on paper, or through an electronic link if the individual agrees to receive it electronically.

There is no such federal requirement. If a state, tribal, or territorial patient consent law requires a parent or legal guardian to complete the prescreening questions for the minor, the CDC COVID-19 Vaccination Program Provider Agreement requires the provider to comply with such a requirement. In addition, if a jurisdiction authorizes a minor to consent to receipt of COVID-19 vaccine, the minor can complete the prescreening questions themselves, but the provider must confirm that this complies with state, tribal, or territorial laws.

A parent or legal guardian may complete the prescreening questions online provided this is done prior to administration of COVID-19 vaccine to the minor. Providers must comply with any applicable state, tribal, or territorial laws.

No. Since applicable medical consent laws are a matter of state, tribal, or territorial law, providers are advised to consult with legal counsel to assure compliance with the scope of those consent laws.

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Page last reviewed: November 24, 2021