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Pfizer, Moderna, Johnson & Johnson: Everything to know about the 3 COVID-19 vaccines

TODAY logo TODAY 4/13/2021 Kerry Breen
© Provided by TODAY

As vaccine eligibility expands across the country, millions of Americans are receiving vaccinations each day. Here is everything you need to know about each of the three options.

Currently, there are three COVID-19 vaccines approved for use in the United States: Pfizer-BioNTech, Moderna, and Johnson & Johnson. All three vaccines have been shown to be effective against the coronavirus.


The Pfizer-BioNTech coronavirus vaccine (an mRNA vaccine) was the first one to be granted authorization in the United States; the Food and Drug Administration (FDA) gave the vaccine an emergency use authorization (EUA) last December. Shots started going into arms in the U.S. on Dec. 14, 2020.

Related: The Centers for Disease Control and Prevention have put out new guidance about what activities fully vaccinated people can resume.

The Pfizer vaccine requires two doses, three weeks apart, and is approved for anyone over the age of 16; people are considered fully vaccinated two weeks after receiving their second dose of the vaccine.

While the vaccine has not been officially approved in pregnant women, pregnant people are encouraged to discuss their options with their doctors. Pfizer launched its clinical trials of its COVID-19 vaccine in pregnant women in February. A recent study of pregnant people who received either the Pfizer or Moderna vaccines found that pregnant or breastfeeding mothers showed a robust immune response to the vaccines, and antibodies were present in their umbilical cord blood and breast milk. The company has also begun clinical trials in children under the age of 16.

Real-world studies show that the vaccine is 90% effective in adults, and preliminary research from clinical trials show the vaccine may be 100% effective in children aged 12 to 15. Recent data also shows that the vaccine is 94% effective at preventing transmission of the virus. The Pfizer-BioNTech vaccine also seems to be effective against variants, with new research showing that it is effective against the South African variant and other research indicating it works against the British variant.


People who receive the Pfizer vaccine may experience mild, flu-like side effects, with the possibility for more severe side effects following the second dose. According to the Centers for Disease Control and Prevention, side effects usually start within a day or two of receiving the vaccine. The most commonly reported side effects include localized reactions like swelling or soreness at the injection site, fatigue, chills, fever or a headache. The CDC recommends people who are not feeling better after 24 hours contact their doctor. There have been some reports of allergic reactions.


Moderna's coronavirus vaccine (also an mRNA vaccine) was granted an EUA by the FDA on Dec. 18, 2020, and people first started receiving doses of the vaccine soon after.

Related: If vaccines can halt asymptomatic spread, then "you could potentially vaccinate your way out of the epidemic," one expert said.

The Moderna vaccine requires two doses, four weeks apart. People who receive the Moderna vaccine are considered fully vaccinated two weeks after their second dose. Real-world studies show that the vaccine is 90% effective in adults. Moderna is currently testing booster shots against the South African variant.

The Moderna vaccine has been approved for adults over the age of 18. Like the Pfizer-BioNTech vaccine, the Moderna vaccine has not been officially approved in pregnant people, but moms-to-be can consult with their doctors to make a decision about receiving vaccinations. A recent study found that new and expectant mothers who received the Moderna or Pfizer vaccines have also passed on antibodies to their children. Moderna has also begun trials in younger children.

The Moderna vaccine has similar side effects as those reported in other coronavirus vaccines. The Moderna vaccine may be more likely to result in mild, temporary skin reactions, such as redness around injection site about a week after receiving a dose of the vaccine.

Related: Young people, women and people who have had the coronavirus report more side effects following COVID-19 vaccinations.

Johnson & Johnson

The Johnson & Johnson vaccine, a viral vector vaccine, was granted an EUA on Feb. 27. On April 13, the FDA and CDC recommended a "pause" in the use of the vaccine "out of an abundance of caution." The agencies are reviewing data involving six cases of a rare and severe type of blood clot in women who received the shot in the days prior. To date, more than 6.8 million people have received the Johnson & Johnson vaccine in the Untied States.

The vaccine requires just one dose. People who receive the Johnson & Johnson vaccine are considered fully vaccinated two weeks after their vaccination.

The Johnson & Johnson vaccine has a lower efficacy rate than the other two vaccines, about 72% in the United States. However, the single-dose vaccine is extremely effective at preventing severe COVID-19, and no clinical trial participants who received the vaccine were hospitalized or died of the coronavirus.

Related: NBC News medical contributor Dr. Kavita Patel joins Weekend TODAY to weigh in on the new Johnson & Johnson COVID-19 vaccine and how it compares to the vaccines from Pfizer and Moderna. “There is absolutely no reason to wait. You should take the vaccine that’s offered,” she says.

The vaccine is authorized in adults aged 18 and up. Like the other two vaccines, it was not tested in pregnant women, but people who are expecting are encouraged to talk with their doctors to make a decision about vaccination. In its application for an EUA, the company said that they plan to test their vaccine in pregnant women and younger children.

The Johnson & Johnson vaccine was tested in Latin America and South Africa, where there are two alarming variants. Experts believe this may account for its lower reported efficacy rate. In Latin America, the Johnson & Johnson vaccine effectiveness was 66%, and in South Africa, the effectiveness fell to 64%. However, even vaccinated people who contracted the variant strains of the virus were not hospitalized.

Clinical trial data showed that the most common side effects were fever, fatigue, headache, muscle aches and pain at injection site. Side effects were common within seven days of getting vaccinated; side effects were more common in people ages 18-59 than in people 60 years and older, according to the CDC.

Related: In the vast majority of people, the benefit of the vaccine would far outweigh the risk, experts say.

The CDC and FDA are currently investigating the six cases of rare and severe blood clots that have been reported in women who received the shot. One case was fatal and one patient is in critical condition. The agencies have stressed that the "adverse events appear to be extremely rare."

Experts have stressed over and over again that all three vaccines are safe and effective, and as soon as you're eligible, get whichever vaccine is offered to you first.

This story was updated on April 13, 2021.



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