What to Know About the Johnson & Johnson COVID Vaccine

A dose of the Johnson & Johnson COVID-19 vaccine is drawn from a vial

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Key Takeaways

  • After an earlier pause, access to the Johnson & Johnson (J&J) vaccine is now limited and only recommended by the CDC and the FDA in some situations.
  • It's formulated differently than the Pfizer and Moderna vaccines, but effective against severe illness, hospitalization, and death related to COVID-19. However, in most situations, the Pfizer and Moderna vaccines are recommended over the J&J vaccine by the CDC.
  • Women younger than 50 years old should be aware of the rare risk of blood clots with low platelets after vaccination.
  • Anyone ages 18 and older who received the J&J vaccine should get a booster shot at least two months after their first round of vaccines. It's recommended to get the Moderna or Pfizer vaccine for the booster shot.

In early 2021, corporate powerhouse Johnson & Johnson (J&J) introduced its own vaccine in the fight against COVID-19. Developed by the company’s pharmaceutical arm Janssen, the J&J vaccine has a different formulation than the Pfizer or Moderna (mRNA) vaccines and requires only a single dose to be effective. The J&J vaccine is authorized for use in people ages 18 and older by the Food and Drug Administration (FDA).

However, due to some safety and efficacy concerns, the Centers for Disease Control and Prevention (CDC) has limited access to the vaccine and recommends getting either the Pfizer or Moderna vaccines over the J&J except under certain circumstances. According to the CDC, the J&J vaccine should only be considered for select groups including those who had a severe reaction after an mRNA vaccine dose or have limited access to the mRNA vaccine options.

How Does the J&J Vaccine Differ From Pfizer and Moderna?

The J&J vaccine was designed differently than the vaccines made by Pfizer and Moderna. First, it's initially delivered in one shot rather than a series of two shots.

Also, the J&J shot is an adenovirus-vectored vaccine rather than an mRNA vaccine. That’s science-speak for a vaccine that uses a common cold virus (commonly called an adenovirus) to hitchhike the coronavirus genes to produce those same viral proteins, explains Dr. Nitin Desai, MD, CEO, and chief medical officer of COVID PreCheck.

Partly because of this, the J&J vaccine has been shown to have a lower rate of effectiveness than its counterparts. Both the Moderna and the Pfizer vaccines boost effectiveness rates in the mid-90% range against hospitalization from the Delta variant.

A study of South African healthcare workers suggests J&J's vaccine is 71% effective at preventing hospitalization from this variant. However, healthcare workers have more exposure to the disease than the average person, so it is difficult to compare the vaccines' rates directly.

The CDC currently recommends mRNA (Moderna or Pfizer) vaccines over the J&J vaccine. This preference is due to the higher risk of side effects associated with J&J's version.

It's worth noting, though, that early clinical trials showed that J&J's vaccine offered complete protection against death from COVID after 28 days. More recent research of healthcare workers in South Africa, showed the J&J shot to be up to 96% effective against death from the Delta variant, specifically.

The Pfizer and Moderna vaccines are the only two that have received a formal FDA stamp of approval beyond emergency use authorization. Full FDA approval means they have passed an extra level of medical review.

In late October 2021, the FDA authorized booster shots for anyone ages 18 and older who received the J&J vaccine, starting two months after their first shot. Strongly recommended by the CDC, these booster shots can be a dose of either Pfizer or Moderna vaccine—"mixing and matching" is fine.

In clinical trials, people who received a booster shot after the J&J vaccine had COVID-19 antibody levels nine times higher than those who received a single shot.

Is the J&J Vaccine Safe? 

Yes. According to Dr. Desai, “The Johnson & Johnson vaccine has an acceptable safety profile and could be an alternative for some with a history of allergies to other vaccines or their ingredients. In clinical trials, there have been fewer severe side effects from the J&J vaccine, including reactions like anaphylaxis."

Nevertheless, two important adverse events have been reported in people who received the J&J vaccine. While rare, these outcomes can be severe.

Blood Clots

Due to reports of six people experiencing a rare and severe type of blood clot after receiving the J&J vaccine, the use of the vaccine was paused to conduct a thorough safety review. The FDA and CDC subsequently lifted the pause, deeming the vaccine safe and effective for use in the U.S.

To date, at least 57 people have developed the blood clotting syndrome after receiving the J&J vaccine (of which more than 17.7 million doses have been given in the U.S.). At least nine of those people died. By contrast, only three cases of blood clotting have been reported out of 513 million doses of mRNA COVID vaccines.

The CDC states the benefits of the J&J vaccine still outweigh its risks if the Pfizer or Moderna vaccines are not possible for that person. In particular, they counsel women between ages 30 and 49 to consider choosing the Pfizer or Moderna vaccine if they are concerned.

Guillain-Barré Syndrome (GBS)

This condition causes damage to the body's nerves from an attack by the immune system, resulting in muscle weakness. GBS can also cause paralysis and long-term nerve damage.

The CDC reports that at least 302 cases of GBS have been found in patients who received the J&J vaccine. Most of the people affected were men over 50, and they typically experienced symptoms of GBS two weeks after receiving the vaccine.

The CDC has not found a link between GBS and the Pfizer or Moderna vaccines.

Despite a higher risk of certain adverse events, the J&J vaccine can be a good option for people who are allergic to the ingredients in mRNA vaccines or who have had a severe reaction to them. Talk to a healthcare provider about which one is the best choice for you.

Should You Get the J&J Vaccine If You're Pregnant?

In studies conducted to date, there is no evidence that there is a detrimental effect of the COVID vaccine on pregnancy, says Dr. Barry Witt, a board-certified reproductive endocrinologist and medical advisor for WINFertility. However, the Pfizer and Moderna vaccines are recommended rather than the J&J vaccine.

“One concern that has been raised is that the coronavirus’s spike protein shares small stretches of the same genetic code as placental protein and that this could result in an immune reaction against the placenta,” Witt says. “However, these proteins are otherwise completely different in structure, and the vaccine does not induce an immune reaction against the placental protein, so this should not be a concern.”

The American College of Obstetricians and Gynecologists (ACOG), the Society for Maternal-Fetal Medicine (SMFM), and the American Society for Reproductive Medicine (ASRM) all recommend COVID-19 vaccination for people who are pregnant or trying to conceive.

ACOG notes that while it considers the J&J vaccine safe for pregnant people, opting for the Pfizer or Moderna vaccines is recommended instead. Studies show that COVID-19 puts a person at higher risk for severe complications during pregnancy.

Additionally, research shows that COVID-19 vaccines actually seem to confer helpful COVID-fighting antibodies to your baby once they're born. Both of these reasons to consider getting the vaccine during pregnancy.

If you are pregnant and have questions about COVID-19 vaccination, the CDC recommends reaching out to MotherToBaby to discuss your concerns with experts trained by the non-profit Organization of Teratology Information Specialists (OTIS). You can call 1-866-626-6847 or start a live chat.

What About My Kids?

Currently, only people 18 years or older are eligible for the J&J vaccines. Children ages 6 months and up can receive the Pfizer and Moderna vaccines. The American Academy of Pediatrics (AAP) recommends immunizing children against COVID-19 as the first line of defense against infection.

According to the AAP, it is safe for kids to receive the COVID vaccine at the same time they get other routine immunizations.

Children were not a part of initial J&J clinical trials, and they will not be eligible to receive the vaccine until it is shown to be effective—and safe—for younger teens and kids.

On April 2, 2021, Johnson & Johnson announced that it had begun testing its vaccine on adolescents between ages 12 and 17. The company may test the vaccine on infants, pregnant women, and people who are immunocompromised as well, but specifics have not yet been released.

Fortunately, evidence continues to show that kids are more likely to experience less severe COVID symptoms if they do become infected. However, the best course of action is to get them vaccinated with the Pfizer or Moderna vaccine.

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.

22 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Christin Perry
Christin Perry is a freelance writer and editor. Her work has been published in The Bump, The Knot, Scary Mommy, LittleThings, Parents, Qeepsake, and more. She has experience writing email marketing campaigns, website copy, and SEO-optimized content. Christin is also a mom of three.