Pfizer vs. Moderna: What’s the Difference?

Close up of a medical tray holding vials of COVID-19 vaccine, syringes, and bandages.

Both Pfizer and Moderna make COVID-19 vaccines that are safe, effective, and free at sites around the U.S., including through Baptist Health. But some people wonder if there are any differences between the two vaccines. 

Yes, there are some minor differences, as this article explains. 

Pfizer and Moderna Are mRNA Vaccines

The Pfizer and Moderna COVID-19 vaccines both use what’s called messenger RNA or mRNA. The mRNA contains genetic instructions that tell cells to make a particular protein found on the COVID-19 virus. When the human immune system detects that protein, it begins developing defenses against it, which prepares it for encounters with the actual virus. 

So, in terms of their approach to producing immunity, the Pfizer and Moderna vaccines are the same.

Effectiveness of the Pfizer and Moderna COVID-19 Vaccines

Both the Pfizer and Moderna COVID-19 vaccines are highly effective in preventing serious illness. That’s been proven in clinical trials involving tens of thousands of participants. 

According to the CDC, the Pfizer vaccine is 95% effective and the Moderna vaccine is 94% effective. 


Don’t take a chance with your health.

Getting the COVID-19 vaccine is the best way to prevent COVID-19 infection and end the pandemic. The vaccine cannot give you COVID-19, but it can help protect you from serious illness. Learn more about the COVID-19 vaccine and make a first, third, or booster vaccination appointment at a location near you. 


Side Effects and Safety of the Pfizer and Moderna COVID-19 Vaccines

The Pfizer and Moderna COVID-19 vaccines — like vaccines for other illnesses — can cause side effects. For both vaccines, the possible side effects include:

  • Pain and redness at the injection site
  • Fatigue
  • Joint pain
  • Muscle pain
  • Fever
  • Chills
  • Nausea 
  • Vomiting

These side effects are generally mild and last a short time. There may also be a slight risk of developing conditions called myocarditis and pericarditis, particularly in adolescents and young adults. This risk is being monitored by the CDC and other health experts.  

As with any vaccine, there also is a risk of severe allergic reaction with the Pfizer and Moderna vaccines. Severe allergic reactions are rare, typically happen soon after injection, and can be treated. That’s why people are required to remain under observation for 15-30 minutes after getting vaccinated.  

Other Differences Between the Pfizer and Moderna COVID-19 Vaccines

Another area of difference between the Pfizer and Moderna COVID-19 vaccines is their use in young people. Testing continues, but the eligibility age continues to drop, meaning that younger people can get the vaccines. Your Baptist Health doctor is your best source for up-to-date eligibility information. 

The transport and storage requirements of the two vaccines are slightly different, as well. The Pfizer vaccine must be shipped and stored at -94º F (-75º C), meaning doctor’s offices and pharmacies need special freezers. Once thawed and placed in a standard refrigerator, the Pfizer vaccine must be used within five days. 

The Moderna vaccine must be shipped and stored at -4º F (-20º C). That temperature is similar to a typical home freezer. After being thawed, the Moderna vaccine can remain in the refrigerator for up to 30 days or at room temperature for 12 hours.

Get Vaccinated Against COVID-19

It’s important to get vaccinated to protect yourself, your loved ones, and your community from COVID-19. What’s the best vaccine? The one that’s available to you! 

Schedule an appointment with Baptist Health or get vaccinated at another authorized site as soon as you can. Vaccination is fast, free, and effective.  


Next Steps and Useful Resources

Schedule Your Vaccine Appointment
Start a COVID-19 Test Online
What Are mRNA Vaccines?
COVID-19 Vaccine Booster Doses and Third Doses Explained
Tips to Mitigate COVID-19 Vaccine Side Effects

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