Everything You Need to Know About the Moderna Vaccine

On January 31, 2022, the FDA granted full approval for use of the Moderna COVID-19 vaccine in people ages 18 and older. The newly approved vaccine is also known as Spikevax.

Moderna's vaccine followed Pfizer-BioNTech's as the second vaccine available in the U.S. to fight the coronavirus pandemic. The Moderna vaccine is recommended by the Centers for Disease Control and Prevention (CDC) to protect against COVID-19.

It's widely available, and more than 261 million doses of Moderna's original vaccine and bivalent booster have been administered in the U.S. to date. Here’s everything your family needs to know about the Moderna vaccine. 

How Does It Compare to the Pfizer Vaccine?

Both the Pfizer and Moderna vaccines are formulated with mRNA technology. Unlike other types of vaccines that trigger an immune response by injecting a weakened or inactivated germ into the body, an mRNA vaccine teaches our cells how to make their own immune response.

It does this by encoding part of the spike protein found on the surface of the virus that causes COVID-19. Both vaccines are administered in two doses—three to eight weeks apart for the Pfizer vaccine and four to eight apart for the Moderna vaccine.

The FDA has authorized a bivalent booster shot from Pfizer or Moderna for all people ages 6 months and older, to be given at least two months after a previous shot (or as part of their Pfizer primary series, if it hasn't been completed yet). This updated booster protects against the Omicron variant, which is predominant in the U.S., as well as the original strain.

Early clinical trials showed that both mRNA vaccines are highly effective against COVID-19, with Pfizer offering 95% protection and Moderna offering 94.1% protection. Research showed that Moderna's vaccine remains 92% effective after 120 days, while the Pfizer vaccine's efficacy drops to 77% after that period.

Neither vaccine was quite as effective against the Delta variant predominating in late 2021, or against the Omicron variant that eventually replaced the Delta variant in prominence. But the bivalent booster is effective against both the original strain and the Omicron variant.

What About My Children?

The Moderna vaccine is now available for everyone ages 6 months and over. (The Pfizer vaccine can also be given to people ages 6 months and over).

The COVID-19 vaccine dosages in children have been determined through extensive clinical trials, with young children getting smaller dosages than adults. "Each vaccine can vary," says Danelle Fisher, MD, pediatrician and vice chair of pediatrics at Providence Saint John’s Health Center in Santa Monica, California.

Dr. Fisher points to the flu vaccine as one example—children under age 8 who are getting the vaccine for the first time need to get two doses, four weeks apart. Thereafter, they get one dose per year, just like adults do.

Can I Get the Moderna Vaccine If I’m Pregnant or Breastfeeding?

The CDC and the American College of Obstetricians and Gynecologists (ACOG) recommend that people who are pregnant get vaccinated against COVID-19.

Pregnant people were not included in early clinical trials of the Moderna vaccine or any other COVID-19 vaccine. Moderna is now performing clinical trials to look at the vaccine's safety and effectiveness in pregnant people, specifically.

A preliminary study published in the New England Journal of Medicine did find that the Moderna vaccine does not pose a serious risk for pregnant people. The findings were based on the CDC's V-safe smartphone-based surveillance system and the CDC's Vaccine Adverse Event Reporting System (VAERS), which included data from 35,691 pregnant people who had received an mRNA vaccine.

In a practice advisory, ACOG recommends that people who are breastfeeding also receive a COVID-19 vaccine. Recent research suggests that breastfeeding people who have received an mRNA vaccine like Moderna's have antibodies in their breast milk, which may provide added COVID-19 protection for the baby.

What to Expect When You Get the Vaccine 

In an FDA briefing document regarding Moderna's COVID-19 vaccine, the following symptoms are listed as potential side effects:

• Chills
• Fever
• Headache
• Injection site pain, swelling, or redness
• Joint pain
  
• Muscle pain
  
• Nausea and/or vomiting
• Tiredness
  

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.