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Everything You Need to Know About the Moderna Vaccine

doctor extracting coronavirus vaccine

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Key Takeaways

  • The Moderna COVID-19 vaccine is the second vaccine to be granted emergency use authorization in the United States.
  • We don't know when children will receive the vaccine, as the first clinical trials included adults only. However, trials have now started in children aged 12 and older.
  • Preliminary data shows that the Moderna vaccine does not appear to have any serious risks for pregnant women, although the CDC and WHO continue to offer conflicting guidance on whether pregnant women should get it.

On December 18, the Food and Drug Administration (FDA) authorized the Moderna COVID-19 vaccine for emergency use, giving the U.S. a second vaccine in the fight against the coronavirus pandemic (the Pfizer vaccine was granted its emergency use authorization on December 11). 

Here’s everything your family needs to know about the Moderna vaccine. 

How Does It Compare to the Pfizer Vaccine?

First of all, here's the science. Both vaccines are made using a new technology, called messenger RNA (mRNA). Unlike many 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 its own immune response. It does this by encoding part of the spike protein found on the surface of SARS-CoV-2, the virus that causes COVID-19, explains the Centers for Disease Control and Prevention (CDC).

Both vaccines are administered in two doses—three weeks apart for the Pfizer vaccine, and one month (28 days) apart for the Moderna vaccine. In terms of efficacy, there’s very little difference between the two—95% for Pfizer and 94.1% for Moderna. 

In any case, you probably won't have a choice between the Pfizer vaccine and the Moderna vaccine. "You'll probably need to take whichever option is available first in your area since both COVID-19 vaccines are currently in short supply," says Ramzi Yacoub, PharmD, chief pharmacy officer at SingleCare.

When Will My Family Get the Vaccine? 

In December 2020, the Advisory Committee on Immunization Practices (ACIP), an independent committee advising the CDC, voted in favor of making healthcare workers and residents of long-term care facilities the top priority for the COVID-19 vaccine.

States each had their own way of moving through priority groups. In general, states had vaccinated older individuals, essential workers, and those with at-risk health conditions first, then moved on to populations with less risk.

Anthony Fauci, MD, head of the National Institute of Allergy and Infectious Diseases, initially estimated that the general public would have vaccine access as early as March. "I had been saying by my calculation, sometime by the end of March, the beginning of April that the normal healthy man and woman in the street, who has no underlying conditions, would likely get it," Fauci told MSNBC on December 14, the day the first vaccines rolled out.

That timeline proved to be quicker than reality, as general access didn't become available until mid-April. But by April 19, 2021, all individuals over the age of 16 were eligible for vaccination in each state.

Dr. Fauci also predicted that by the second quarter of 2021, the U.S. could see the "overwhelming majority of the population vaccinated." As of April 19, around 50% of adults in America have had at least one vaccine dose.

What About My Children?

Currently, the Moderna vaccine is only authorized for adults aged 18 and over (the Pfizer vaccine can be given to those aged 16 and over). However, both Pfizer and Moderna recently began new vaccine trials including children as young as age 12. If those trials are successful, the next step will be FDA review, before the vaccines are produced and distributed. 

On November 29, Dr. Fauci told NBC it was “going to be months” before the vaccine was approved for children, stating, “You want to make sure you have a degree of efficacy and safety that is established in an adult population—particularly an adult, normal population.” 

Danelle Fisher, MD

Get your children a flu vaccine if they haven’t gotten one yet. No one wants to have the flu plus COVID-19.

— Danelle Fisher, MD

Until studies are carried out on children, we won't know how many doses of the COVID-19 vaccine they'll require. "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. "Get your children a flu vaccine if they haven’t gotten one yet," Dr. Fisher recommends. "No one wants to have the flu plus COVID-19."

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

A preliminary study published in the New England Journal of Medicine on the safety of mRNA vaccines in pregnant people found that the Moderna vaccine does not appear to pose a serious risk for this population. 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 participants (ages 16 to 54) who were pregnant between December 14, 2020 to February 28, 2021.

At this time, there is still no data from those in this population who were vaccinated during the first trimester. Pregnant people also haven't been actively involved in late-stage clinical trials for any COVID-19 vaccines, including the Moderna vaccine. This means there’s limited data on whether the vaccine is safe and/or effective for pregnant people.

The CDC says people who are pregnant may choose to be vaccinated. This extends to anybody who is breastfeeding. None of the COVID-19 vaccine trials have included lactating individuals either, so there’s also a lack of data for that group. 

The WHO, on the other hand, says pregnant people should not get the vaccine unless they are at high risk of COVID because of work exposure or a chronic condition. The WHO recommends offering the Moderna vaccine to women who are breastfeeding, however, and currently does not recommend discontinuing breastfeeding after vaccination.

In a practice advisory updated in April 2021, The American College of Obstetricians and Gynecologists (ACOG) recommended that COVID-19 vaccines shouldn’t be withheld from pregnant or lactating people. 

Sherry Ross, MD, OB/GYN and women’s health expert at Providence Saint John’s Health Center in Santa Monica, California, advises discussing the information with your doctor. “Even though you are pregnant or breastfeeding, it may be in your best interest to take the COVID-19 vaccine,” she says. “The choice is yours, in conjunction with your healthcare provider.”

Sherry Ross, MD

Even though you are pregnant or breastfeeding, it may be in your best interest to take the COVID-19 vaccine. The choice is yours, in conjunction with your healthcare provider.

— Sherry Ross, MD

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:

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

It's possible that children might experience different side effects, says Dr. Fisher. "I would be curious to know about gastrointestinal side effects such as abdominal pain or diarrhea," she says. "Both of those symptoms can be more prevalent in children than adults who get COVID-19. I do hope the rate of side effects is low and that they are mild in nature."

What This Means For You

As of April 19, 2021, all individuals 16 and over are eligible for Moderna vaccine. Children and adolescents might not be offered the vaccine until at least the second half of 2021.

In the meantime, it's crucial to continue to follow the safety guidelines provided by the CDC, as well as any local restrictions. That means staying home as much as possible, wearing a mask when you're out in public, and staying six feet away from other people. When you do meet others, gather outside as much as possible.

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Article Sources
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  2. Centers for Disease Control and Prevention. Understanding mRNA COVID-19 vaccines. Updated March 4, 2021.

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  6. The White House. Remarks by President Biden on the COVID-19 Response and the State of Vaccinations. Published April 21, 2021.

  7. Connecticut Children's. When will the COVID-19 vaccine be available for kids, and will it be safe for your family?. Published December 24, 2020.

  8. Centers for Disease Control and Prevention. Flu & young children. Updated October 15, 2020.

  9. Centers for Disease Control and Prevention. Vaccination considerations for people who are pregnant or breastfeeding. Updated March 18, 2021.

  10. World Health Organization. The Moderna COVID-19 (mRNA-1273) vaccine: what you need to know. Published January 26, 2021.

  11. American College of Obstetricians and Gynecologists. Vaccinating pregnant and lactating patients against COVID-19. Updated April 24, 2021.