Pfizer-BioNTech COVID-19 Vaccine

Introduction

• CDC latest recommendations (May 1, 2023) are that monovalent (original) mRNA vaccines are no longer recommended in the US.
• Almost the entire US population already has antibody against SARS-CoV-2 from previous infection or vaccination.
  • Unvaccinated individuals need only to receive a single dose of a bivalent vaccine, rather than multiple doses of the original monovalent mRNA vaccines. 
• A single additional bivalent vaccine dose for adults >65 years and 1 or more additional doses for people who are immunocompromised are now recommended.
  • The updated FDA EUA states that most immunocompromised persons who have received a bivalent COVID-19 vaccine may receive a single additional dose of a bivalent vaccine >2 months following a dose of a bivalent vaccine, and additional doses may be administered at the discretion of, and at intervals determined by, their healthcare provider.
• All persons >6 yrs should receive a bivalent mRNA vaccine, regardless of previous completion of a monovalent primary series.
• Persons  >6 yrs who have already received a bivalent mRNA vaccine need no further doses unless they are >65 years or immunocompromised.
• See COVID-19, Vaccines.

Vaccine

• Type:  Lipid nanoparticle (LNP) encapsulated mRNA
• Pfizer COVID-19 Vaccine, Monovalent (original strain)(Comirnaty, mRNA BNT162b2)
• Pfizer COVID-19 Vaccine, Bivalent (original and Omicron BA.4/BA.5). Not branded at present.

Dose and Schedule (normal host)

• Available Pfizer vaccine vials in the US. Choice of vials (differential color-coding) should be under the supervision of a pharmacist.
• In general, persons should receive the age-appropriate vaccine product and dosage based on their age on the day of vaccination in accordance with the recommended intervals for that age group; certain 4 and 5 yr olds present exceptions.
• Normal host = not moderately or severely immunocompromised.

• Abbreviated, non-comprehensive CDC infographic

Age >12 yrs

• *Additional bivalent dose. Persons 65 years and older have the option to receive 1 additional bivalent mRNA vaccine dose >4 months after the first dose of a bivalent mRNA vaccine. If Pfizer is used, administer 0.3 mL/30 ug

Toxicities

Contraindications

• Anaphylaxis or immediate allergic reaction (within 4h) to a previous dose of an mRNA vaccine or separately to a vaccine constituent including polyethylene glycol (PEG) or polysorbate.
• Do not vaccinate with any mRNA vaccine
• History of a known diagnosed allergy to a vaccine component

Precautions

• Immediate allergic reaction (within 4h) to any other vaccine or injectable therapy not related to a component of mRNA-COVID-19 vaccines or polysorbate.
• Persons with a reaction to a vaccine or injectable therapy that contains PEG.
• History of MIS-C or MIS-A.
• History of myocarditis or pericarditis after a dose of an mRNA or Novavax COVID-19 vaccine, is a precaution to future doses of any COVID-19 vaccine but wait until episode is completely resolved.
• Myocarditis or pericarditis unrelated to mRNA or Novavax COVID-19 vaccination; administer any age-appropriate vaccine after the episode has resolved.
• Allergy-related contraindication to one type of COVID-19 vaccine is a precaution to the other types of COVID-19 vaccines.
• Defer vaccination until resolution of a moderate or severe acute illness, with or without fever.

Not Contraindications

• Food (including egg and gelatin), pet, insect, venom, environmental, latex, oral medications; any other history of anaphylaxis not related to vaccine or injectables.
• History of GBS in proximity to another vaccine.

Adverse Effects

• Safety similar whether monovalent or bivalent vaccine is used as a 4th dose (2nd booster).
• Myocarditis: 131 myocarditis cases reported to VAERS after 123 million mRNA booster vaccinations.
  • Risk primarily in adolescent and young adult males
  • No increase in children age 5–11 yrs following 1st booster
  • Rates are lower following 1st booster dose vs. dose 2 of primary series (and lower following dose 1 vs. dose 2 of primary series)
  • An 8-week interval between the first and second primary series doses of Moderna, Novavax, and Pfizer COVID-19 vaccines may be optimal to reduce myocarditis.
• No safety signals for ischemic stroke with mRNA vaccines with primary doses or monovalent boosters in US or any other country.
  • One small cluster of ischemic stroke after a bivalent booster in persons >65 at a single reporting site in 1 of several US CDC and Pfizer surveillance networks needs further investigation. 
    
  • Possible association with concomitant adjuvanted influenza vaccine needs study prior to 2023-24 flu season.

Pregnancy

• Vaccinate according to standard recommendations if pregnant, breastfeeding, attempting or contemplating conception.

• Pregnant and recently pregnant persons at increased risk for severe illness and the fetus is at increased risk.

• Benefits outweighs risks of vaccination.
• Antibodies are transferred to the newborn.
• No contraindications to breastfeeding.

Severely or Moderately Immunocompromised / HIV

• Available Pfizer vaccine vials in the US. Choice of vials (differential color-coding) should be under the supervision of a pharmacist.

• For immunocompromised persons, abbreviated, non-comprehensive CDC infographic<https://www.cdc.gov/vaccines/covid-19/downloads/COVID19-vaccination-recommendations-immunocompromised.pdf>

Age >12 yrs

• Footnote: *Immunocompromised persons ages >12 yrs  have the option to receive 1 additional dose of Moderna  (0.5 mL/50 ug); or Pfizer (0.3 mL/30 ug ) >2 months following the last recommended bivalent dose. Further additional dose(s) may be administered, informed by clinical judgement and personal preference and circumstances > 2 months after the last vaccine dose.

• If possible, COVID-19 vaccines should be administered >2 wks before initiation or resumption of immunosuppressive therapies.
• Persons with HIV not at higher risk of severe disease after completing vaccination.
  • Severe disease risk higher if CD4<350 even with vaccination;  ensure up to date with bivalent boosting.
    
• NCCN recommends against Novavax in active cancer patients unless no choice.
• Self-attestation to moderately or severely immunocompromised status is acceptable.
• New immunocompromise after a 2-dose primary series, no additional primary doses;  immunocompromised schedule for the booster dose.
• Revaccinate HCT or CAR-T-cell therapy recipients with an mRNA vaccine or Novavax >3 mos after HCT or CAR-T-cell therapy .

• Consider revaccination if 1 or more doses of vaccine (primary series and bivalent booster doses) received during short-course treatment with B-cell-depleting therapies (e.g., rituximab, ocrelizumab)  begining at about 6 mos after completion of therapy.

• Administration of vaccines should not be delayed in patients on ongoing immunosuppressives.
• Administer vaccine doses approximately 4 wks before the next scheduled therapy for patients on ongoing B-cell-depleting therapies.
• Tixagevimab/cilgavimab (Evusheld) no longer recommended as prophylaxis.
• On a case-by-case basis, providers may administer Moderna, Novavax, and Pfizer vaccines outside of the FDA and CDC dosing intervals using a risk-benefit approach together with clinical experience and judgement.
  

Serologic Testing

• Antibody testing is not recommended to assess for immunity following COVID-19 vaccination or to assess the need for vaccination in an unvaccinated person.
• No correlates of protection are available and assays vary widely.
• +ve IgG only minimally reassuring, -ve IgG unhelpful in patients whose ability to mount a B-cell response is uncertain.
• If antibody testing is done, vaccination should be completed as recommended regardless of the antibody test result.
• Prior receipt of a COVID-19 vaccine will not affect the results of SARS-CoV-2 viral tests (nucleic acid amplification or antigen tests).

Comments

• Consider 15 minute observation period post-administration especially for adolescents.
• Consider 30 minute observation period post-administration if:
  • Allergy related contraindication to another COVID vaccine
  • Non-severe allergic reaction (within 4 hrs) to any previous COVID vaccine
  • Anaphylaxis after non-COVID-19 vaccines or injectable therapies
• Age-appropriate vaccine product and dosage is based on age on the day of vaccination. A move from a younger age group to an older age group during the primary series, requires the vaccine product and dosage for the older age group.
• Vaccines are not recommended for outbreak management or for post-exposure prophylaxis
• mRNA vaccines do not have a risk of modifying the vaccine recipient’s genetic makeup as mRNA does not enter cell nucleus where host DNA is located.