Moderna and Pfizer-BioNTech have both developed safe, effective vaccines protecting against severe COVID-19 illness that have received an Emergency Use Authorization (EUA) by the Food and Drug Administration in December. To better understand the differences and similarities between the two vaccines – and what that means for you – please reference the information outlined below.
The two vaccines are virtually identical in most aspects, which include:
- Both Moderna and Pfizer vaccines are based on mRNA technology, which shows our bodies how to make the spike protein found in the SARS-Cov-2 virus (and that it uses to invade our cells). If ever infected with the actual virus, the immune system is then triggered to produce antibodies toward it to prevent illness.
- Both vaccines are approximately 95% effective in preventing COVID-19 illness after two doses.
- No other vaccines should be administered within 14 days prior or after receiving either the Moderna or Pfizer COVID-19 vaccine.
- Both vaccines were found to be extremely tolerable, with no serious safety concerns identified in Phase 3 clinical trials.
- Approximately 80% of people may develop a mild local symptom (pain at injection site).
- Some may develop more systemic symptoms (fatigue, body aches, chills, fever, etc.) that subside after approximately 24 hours.
Second dose requirement and interval
- UW Medicine is scheduling second doses of both the Pfizer and Moderna vaccine at a minimum 24 days after the first dose.
- There is no upper limit to receiving second dose, but the ideal timing is before 28 days since the first dose.
Full vaccination status
- Patients can be considered fully vaccinated one to two weeks after receiving either vaccine.
COVID-19 exposure or illness
- If you have had COVID-19 in the past 90 days, you may wait to receive the vaccine until the end of the 90-day period.
- With both vaccines, if you are diagnosed with COVID-19 between doses, you should defer your second dose until your symptoms have completely resolved and your healthcare provider has deemed you are safe to return to work.
Bell’s Palsy or Guillain-Barre Syndrome (GBS)
- No cases of GBS have been reported with either of the two COVID-19 mRNA vaccines. Per CDC guidance, persons with a history of GBS may receive either of the mRNA vaccines. Similarly, there have not been cases of Bell’s Palsy reported higher than baseline rates among unvaccinated individuals.
There are also a few key differences between the two vaccines:
- Pfizer – must be shipped and maintained at -94 degrees Fahrenheit for long-term storage, but can be placed in a refrigerator for up to five days
- Moderna – can be shipped and maintained at a standard freezer temperature of -4 degrees Fahrenheit, and can stay in a refrigerator for up to 30 days
- Pfizer – vial must be thawed and then diluted with saline prior to injection
- Moderna – ready to be administered as is
Minimum age to vaccinate
- Pfizer – 16 years of age
- Moderna – 18 years of age (however the company has begun testing the vaccine in 12- to 17-year olds)
If you have any other questions, please read the UW Medicine COVID-19 Vaccine FAQ, reach out to your manager or contact the UW Medicine vaccine team at email@example.com. Employees and students may also call the vaccine hotline at 206.520.8788.