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COVID-19 Vaccine Q&A

– updated March 2021

FARE Update on mRNA Vaccines Against COVID-19

Vaccine

The Pfizer-BioNTech COVID-19 vaccine received emergency use authorization from the U.S. Food and Drug Administration (FDA) on December 11, 2020. A similar COVID-19 vaccine, developed by Moderna, received emergency use authorization on December 18, 2020. On February 27, 2021, FDA granted emergency use authorization to a third COVID-19 vaccine by Janssen Pharmaceuticals of Johnson & Johnson.

At present, demand for these vaccines is outpacing supply. Increasing numbers of Americans recognize that vaccination can limit the dangers of COVID-19 and expand their opportunities to socialize safely.

Reports of serious allergic reactions to the Pfizer-BioNTech vaccine and at least one report of serious allergic reaction to the Moderna vaccine have led to new guidance from the Centers for Disease Control and Prevention (CDC) and a plan to study what’s behind these reactions by the National Institutes of Health (NIH), with new insights coming each day. Here’s what we’ve learned so far.

***Be sure to check back here often as FARE will update this page regularly to reflect new findings and information relating to COVID-19 vaccines***

Who can receive a COVID-19 vaccine?

  • The Pfizer-BioNTech vaccine has received emergency authorization for use in individuals 16 years of age and older, and studies are underway to test the vaccine in adolescents aged 12-15.
  • The emergency use authorization for the Moderna vaccine is limited to adults, aged 18 and older, and studies are underway to test the vaccine in adolescents aged 12-17.
  • The emergency use authorization for the Janssen vaccine is limited to adults, aged 18 and older.
  • While the CDC offers recommendations for how to assign the limited supply of vaccines to individuals, eligibility requirements to receive a vaccine vary from state to state.

How are the three vaccines similar? How are they different?

The Pfizer-BioNTech and Moderna are similar to each other and different from the Janssen vaccine, but all three vaccines have important details in common.

Types of Vaccine

mRNA vaccines

  • The vaccines by Pfizer-BioNTech and Moderna are mRNA vaccines. Both of the vaccines contain instructions for making the spike protein of the coronavirus that causes COVID-19; these instructions are in a molecule of genetic material called mRNA. The spike protein on its own can’t cause disease.
  • The mRNA vaccine technology is not new, but had not been used in humans before now. To better understand how mRNA vaccines work you can check out our primer on mRNA vaccines.
  • In both mRNA vaccines, the mRNA is surrounded and protected by fats (lipids) that help the mRNA enter human cells. Some of these lipids are attached to polyethylene glycol (PEG). PEG has many uses in medicine and biology.
  • Scientists have proposed that PEG might trigger serious allergic reactions in a small number of individuals, but the cause of allergic reactions to vaccines remains to be determined. NIH is starting a large trial to explore allergic reactions to both mRNA vaccines.
  • The mRNA vaccines do not contain deactivated (killed or weakened) virus.

Viral-Vectored Vaccine

  • The vaccine by Janssen is a viral-vectored vaccine. Like the Pfizer-BioNTech and Moderna vaccines, the Janssen vaccine contains instructions to make the coronavirus spike protein. However, in the Janssen vaccine, these instructions are a molecule of DNA, not mRNA. This DNA is carried into human cells by a virus that has been changed (deactivated) so that it can’t use the cells to make copies of itself like an active virus can.
  • This deactivated virus is not the coronavirus that causes COVID-19. Instead, it is a harmless version of an adenovirus. Active adenoviruses typically cause mild cold- or flu-like illness, but the deactivated virus in the Janssen vaccine cannot cause any viral disease.
  • A similar approach was used to develop a vaccine against Ebola virus.
  • The Janssen vaccine does not contain PEG. However, the Janssen vaccine does contain another common ingredient called polysorbate-80, which may trigger reactions in individuals with allergy to PEG.

Number of Doses

  • While a two-dose regime of the Janssen vaccine is currently being studied in clinical trials, the Janssen vaccine is currently authorized for use as a single dose. This differs from the vaccines by Pfizer-BioNTech and Moderna, which have been authorized for use as two doses delivered weeks apart for maximum effectiveness.
    • Both doses should deliver the same vaccine, either Pfizer-BioNTech or Moderna.
    • The time between doses is 21 days for the Pfizer-BioNTech vaccine and 28 days for the Moderna vaccine.

Effectiveness of Vaccines*

  • It’s difficult to compare the effectiveness of the three vaccines head to head, because the Pfizer-BioNTech and Moderna vaccines were tested earlier, in different countries, against different virus variants, and with different endpoints (benchmarks for measuring effectiveness) than the Janssen vaccine.
  • The effectiveness results below start at 7 days after the second dose of the Pfizer-BioNTech vaccine, 14 days after the second dose of the Moderna vaccine and 28 days after the Janssen vaccine.
  • For all three authorized vaccines, no COVID-19 hospitalizations or deaths occurred in people who received active vaccine rather than placebo during large clinical trials.
  • Both the Pfizer-BioNTech and Moderna vaccines are more than 90 percent effective in preventing symptomatic COVID infections after two doses. 
  • Both the Pfizer-BioNTech and Moderna vaccines approach 100 percent effectiveness in preventing severe COVID disease after two doses.
  • The Janssen vaccine is 66% effective overall, and 72% effective in the U.S., in preventing moderate or severe COVID disease after one dose.
  • The Janssen vaccine is 85% effective, regardless of clinical trial location, in preventing severe COVID disease after one dose.

*Levels of effectiveness may change as new coronavirus variants arise and spread and the current rate of infection changes.

Vaccine Storage

  • The emergency use authorization for the Pfizer-BioNTech vaccine lists extremely low storage temperatures, between -80ºC and -60ºC (-112ºF to -76ºF). As an alternative or complement to storage in an ultra-low temperature freezer, Pfizer has submitted new data to FDA demonstrating the stability of their COVID-19 vaccine when stored for a total of two weeks at -25°C to -15°C (-13°F to 5°F), temperatures more typical for pharmaceutical freezers.
  • The Moderna vaccine can be stored frozen between -25°C and -15°C (-13°F and 5°F) or, prior to first use, stored refrigerated between 2° to 8°C (36° to 46°F) for up to 30 days.
  • The Janssen vaccine should not be frozen and can be stored refrigerated at 2°C to 8°C (36°F to 46°F).

Similarities Among Vaccines Ingredients

  • The vaccines do not contain mercury or other preservatives.
  • The vaccines do not contain egg or other food allergens.
  • The vaccine vials do not contain latex.

Comparison of COVID-19 Vaccines With Emergency Use Authorization

Number of doses required

  • Pfizer-BioNTech: Two
  • Moderna: Two
  • Janssen: One

Efffectiveness in clinical trial*

  • Pfizer-BioNTech: 95% effective at preventing symptomatic disease; nearly 100% effective in preventing severe disease; 100% effective at preventing hospitalization or death
  • Moderna: 94.1% effective at preventing symptomatic disease, 100% effective in preventing severe disease; 100% effective at preventing hospitalization or death
  • Janssen: 66% effective at preventing moderate or severe disease; 85% effective at preventing severe disease; 100% effective at preventing hospitalization or death

Contains mRNA?

  • Pfizer-BioNTech: Yes
  • Moderna: Yes
  • Janssen: No

Contains polyethylene glycol (PEG)?

  • Pfizer-BioNTech: Yes
  • Moderna: Yes
  • Janssen: No

Contains polysorbate?

  • Pfizer-BioNTech: No
  • Moderna: No
  • Janssen: Yes

Contains DNA?

  • Pfizer-BioNTech: No
  • Moderna: No
  • Janssen: Yes

Contains inactive virus?

  • Pfizer-BioNTech: No
  • Moderna: No
  • Janssen: Yes

Contains preservative?

  • Pfizer-BioNTech: No
  • Moderna: No
  • Janssen: No

Contains food ingredients?

  • Pfizer-BioNTech: No
  • Moderna: No
  • Janssen: No

Contacts latex in packaging?

  • Pfizer-BioNTech: No
  • Moderna: No
  • Janssen: No

Authorized for use in older children?

  • Pfizer-BioNTech: Yes, ages 16 and up
  • Moderna: No, ages 18 and up
  • Janssen: No, ages 18 and up

Requires special storage?

  • Pfizer-BioNTech: Yes. Currently stored in an ultra-low temperature freezer, although data to support storage for up to two weeks at conventional freezer temperatures has been submitted to FDA.
  • Moderna: No. Stored in a conventional freezer. Unopened vials can be stored for up to 30 days in a conventional refrigerator.
  • Janssen: No. Stored in a conventional refrigerator. Should not be frozen.

U.S. Food and Drug Administration, 2020, 2021
*These levels of effectiveness may change as new coronavirus variants arise and spread.

Can I Receive an mRNA COVID-19 Vaccine?

The table below summarizes CDC guidance about the two authorized mRNA COVID-19 vaccines and allergies. The CDC has not yet released guidance about the Janssen vaccine and allergies. The FDA emergency use authorization for the Janssen vaccine indicates that individuals who have had a severe allergic reaction to any ingredient* in the Janssen vaccine should not receive the Janssen vaccine. 

 

No

  • Severe allergic reaction (anaphylaxis) or immediate allergic reaction (within 4 hours of exposure) to any COVID-19 mRNA vaccine ingredient, including polyethylene glycol (PEG)*
  • Severe or immediate allergic reaction to polysorbate, which may trigger reaction in a person allergic to PEG**
  • Severe or Immediate allergic reaction to the first dose of a COVID-19 mRNA vaccine.

 

Consult with your doctor

  • Severe or immediate allergic reaction to another vaccine or injectable therapy

 

Yes

  • Severe allergic reaction to oral medications
  • Severe allergic reaction to other allergens, including foods
  • Mild allergic reactions only
  • Family history of severe allergic reactions

Centers for Disease Control and Prevention, 2020, 2021. * Vaccine ingredients are listed at the bottom of this webpage. ** The Pfizer-BioNTech and Moderna vaccines do not contain polysorbate, but the Janssen vaccine does contain polysorbate.

Were severe allergic reactions to the vaccines reported during clinical trials?

There were no serious allergic reactions reported during the clinical trials for the Pfizer and BioNTech or Moderna vaccines. However, individuals with a history of anaphylaxis were excluded from the trials.

Two severe allergic reactions, including one case of anaphylaxis, have been reported following administration of the Janssen vaccine during clinical trials.
 

What is being done to learn more about severe allergic reactions to COVID-19 vaccines?

***FARE will continue updating these resources as new information becomes available.***

On February 12, 2021, the Centers for Disease Control and Prevention (CDC) published in JAMA (Journal of the American Medical Association) an update on allergic reactions to the Pfizer-BioNTech vaccine and the Moderna vaccine. Of more than 9.9 million doses of the Pfizer-BioNTech vaccine and nearly 7.6 million doses of the Moderna vaccine administered in the U.S. from December 14, 2020 through January 18, 2021, CDC identified 66 anaphylactic reactions, which reflected 4.7 anaphylactic reactions per million doses of the Pfizer-BioNTech vaccine (47 of 66 reactions), and 2.5 anaphylactic reactions per million doses of the Moderna vaccine (19 of 66 reactions). Among the 66 individuals who had an anaphylactic reaction following vaccination, roughly one-third had a previous history of anaphylaxis, and more than three-quarters had a history of allergies or allergic reactions. Most prior anaphylactic reactions involved vaccines, drugs or other medical products, but some involved walnuts, unspecified tree nuts or unspecified food allergens.

Of the 66 individuals who experienced anaphylaxis following the Pfizer-BioNTech or Moderna vaccines: 

  • 100 percent survived (no deaths)
  • 92 percent received epinephrine
  • 52 percent received care in an emergency department
  • 48 percent were hospitalized
  • 27 percent received intensive care
  • 11 percent required intubation

For the Pfizer-BioNTech vaccine, the rate of severe allergic reactions reported on February 12 represented a 58 percent decline from the initial rate reported on January 6. For the Moderna vaccine, the rate of severe allergic reactions reported on February 12 was unchanged from the initial rate reported on January 21. The data reported in January reflected reactions to first doses only, whereas the data reported in February included reactions to some second doses.

The National Institute of Allergy and Infectious Diseases (NIAID), part of the NIH, is sponsoring a clinical study of the Pfizer-BioNTech and Moderna vaccines in individuals with histories of severe allergic reaction. Researchers hope to identify the allergenic component of the vaccine.

If you have questions, please don’t hesitate to contact the FARE Communications team at media@foodallergy.org.

Vaccine Ingredients

In addition to modified mRNA instructions for making the SARS-CoV-2 spike protein, the Pfizer-BioNTech vaccine also includes 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-phosphopolcholine, 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, and 6 mg sucrose. The diluent (0.9% Sodium Chloride Injection, USP) contributes an additional 2.16 mg sodium chloride per dose.

In addition to modified mRNA instructions for making the SARS-CoV-2 spike protein, the Moderna vaccine also includes lipids (SM-102, polyethylene glycol [PEG] 2000 dimyristoyl glycerol [DMG], cholesterol, and 1,2-distearoyl-sn-glycero-3-phosphocholine [DSPC]), 0.31 mg tromethamine, 1.18 mg tromethamine hydrochloride, 0.043 mg acetic acid, 0.12 mg sodium acetate, and 43.5 mg sucrose.

In addition to deactivated virus particles that provide DNA instructions for making the SARS-CoV-2 spike proteins, the Janssen vaccine also includes citric acid monohydrate (0.14 mg), trisodium citrate dihydrate (2.02 mg), ethanol (2.04 mg), 2-hydroxypropyl-β-cyclodextrin (HBCD) (25.50 mg), polysorbate-80 (0.16 mg), sodium chloride (2.19 mg). Each dose may also contain residual amounts of proteins (≤0.15 mcg) and/or DNA (≤3 ng) from the human cell line in which the virus particles were grown.
 

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