What’s the Difference Between Vaccines From Moderna and Pfizer?

Provided by UPMC - January 19, 2021

In December, the Food and Drug Administration (FDA) granted Emergency Use Authorization (EUA) for two COVID-19 vaccines. An EUA means the FDA has determined the vaccines are safe and effective enough to recommend for preventing COVID-19. No COVID-19 vaccine has received full FDA approval as past vaccines have, which takes more time.

The pharmaceutical companies Pfizer and BioNTech developed one, and the company Moderna developed the other. While both vaccines are mRNA vaccines that require two doses, they have some differences as well. Below is more on how these vaccines work, how they are similar, and how they differ.

Similar Vaccine Effectiveness

Both vaccines have high effectiveness based on clinical trials in tens of thousands of people of different races and ethnicities. The Pfizer vaccine protects 95% of people who receive it from COVID-19 disease. The Moderna vaccines protect 94% of people who receive it from COVID-19 disease.

Both vaccines also protect against severe disease in the small number of people who still develop COVID-19 after vaccination. None of the people who received either vaccine during clinical trials needed hospitalization.

Neither vaccine has been tested in children or people who are pregnant, breastfeeding, taking anti-clotting medications, or taking immune-suppressing medication.

Similar Side Effects and Vaccine Safety

The Pfizer and Moderna vaccines have similar side effects. Many people who receive either vaccine had mild pain at the injection site, tiredness, or headache. The following mild side effects were also common in both vaccines:

· Muscle pain

· Fever

· Chills

· Joint pain

· Nausea or vomiting

A severe allergic reaction, called anaphylactic reactions, is possible with any vaccine, including both the Pfizer and Moderna vaccines. A severe anaphylactic reaction means the person has to use an EpiPen or other epinephrine device or to go to the hospital.

Anaphylaxis is rare, according to monitoring data and clinical trials. People who have a history of allergy or anaphylaxis should follow guidelines on receiving or deferring the vaccine. Everyone should monitor their symptoms and seek care if they experience a reaction.

Everyone who had severe allergic reactions received treatment and recovered completely. No one has died because of receiving the Pfizer or Moderna vaccines. People with a history of severe anaphylactic reactions should speak to their doctor with any questions about getting the vaccine.

Differences Between Pfizer and Moderna Vaccines

The Pfizer vaccine can be administered to anyone age 16 and older while only adults age 18 and older can receive the Moderna vaccine. Both companies are currently testing the vaccine in youth aged 12 and older.

Both vaccines require two doses, but the time between doses is different. People receive the second dose of the Pfizer vaccine is at least 21 days after the first dose. The time between Moderna doses is at least 28 days.

Both vaccines require specialized cold storage, but the Pfizer vaccine has much colder temperature requirements. The Pfizer vaccine requires -94º F (-75º C) for shipping and storage, much colder than typical freezers at doctors’ offices and pharmacies. After it thaws, the Pfizer vaccine remains good for 5 days in a normal refrigerator.

The Moderna vaccine requires -4º F (-20º C) for shipping and storage, similar to a typical home freezer. Once opened, the Moderna vaccine remains good at refrigerator temperature for 30 days and at room temperature for 12 hours.


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