What to Know About the Johnson & Johnson COVID Vaccine

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Key Takeaways

  • After an earlier pause, the Johnson & Johnson (J&J) vaccine is recommended by the CDC and the FDA.
  • It's formulated differently than the Pfizer and Moderna vaccines, but effective against severe illness, hospitalization, and death related to COVID-19.
  • 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, according to the CDC. Booster shots for the Moderna and Pfizer vaccines are recommended five months after the first series.
  • The J&J vaccine has been approved for use as a booster dose in people who received the Moderna or Pfizer vaccine for their first COVID-19 series.

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 vaccines and requires only a single dose to be effective.

After some early hiccups, including a temporary pause in its availability as rare cases of blood clots were being investigated, the J&J vaccine is recommended by the Centers for Disease Control (CDC) and approved for emergency use authorization in people ages 18 and older by the Food and Drug Administration (FDA).

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 boast effectiveness rates in the mid-90% range against hospitalization from the Delta variant. A study of South African healthcare workers suggest J&J's vaccine is 71% effective at preventing hospitalization for the Delta 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.

Pfizer's is still the only vaccine that has received a formal FDA stamp of approval beyond the emergency use authorization. Full FDA approval means it's 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 the J&J, 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.”

That’s great news for people who might be wary of vaccines and thus struggling with the decision to get this important shot. “In clinical trials, there have been fewer severe side effects from the J&J vaccine, including reactions like anaphylaxis,” Desai says.

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, 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.). Nine of those people died. By contrast, only three cases of blood clotting have been reported out of 496 million doses of mRNA COVID vaccines.

The CDC states the benefits of the J&J vaccine still outweigh its risks. However, 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 about 294 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.

“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, those concerned about rare cases of blood clots can opt for the Pfizer or Moderna vaccines 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 and Moderna vaccines. Children ages 5 and up can receive the Pfizer vaccine. The American Academy of Pediatrics (AAP) recommends immunizing children against COVID-19 as a 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. That makes it all the more important for adults to be vaccinated.

On April 2, Johnson & Johnson announced that it had begun testing its vaccine on adolescents between ages 12 and 17. It does plan to 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.

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.

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