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What You Need to Know About the Johnson & Johnson Vaccine

By Debbe Geiger
Updated August 09, 2021
Duke provider administers J&J COVID-19 vaccine at drive-through Duke Health clinic.

Duke provider administers J&J COVID-19 vaccine at drive-through Duke Health clinic.

There’s no question that being vaccinated against COVID-19 is your best form of protection against the virus. And the sooner people get vaccinated, the faster the pandemic will end. The Johnson & Johnson (J&J) COVID-19 vaccine is easy to distribute and store.

Dr. Cameron Wolfe, MBBS, a Duke Health infectious disease expert, wants people to on getting vaccinated. “I worry that people will delay getting vaccinated as they hunt for a site that gives them the vaccine they want,” he said. “This will only increase their risk for getting COVID-19 and negate any perceived benefit one vaccine has over another.” To set the record straight, here's what you need to know about the J&J vaccine.

How the J&J COVID-19 Vaccine Works

The J&J vaccine (also called the Johnson & Johnson's Janssen COVID-19 vaccine) uses an inactivated cold virus to carry genetic material, which prompts your cells to create a harmless piece of the “spike protein” found on the surface of COVID-19. This helps the body build an immune response against the coronavirus that causes COVID-19. These types of vaccines have been around for years and are generally safe for large populations of people.

The J&J vaccine will not give you a cold. “The virus has been inactivated so it won’t make you sick,” Dr. Wolfe said.

Pfizer and Moderna vaccines do not use inactive virus. Rather, they use genetic material (called mRNA) to instruct the cells in your body to make the same spike protein. “Once the spike protein is created, the vaccines work essentially the same way,” he said.

One Dose or Two: Does It Matter?

From an effectiveness standpoint, it doesn’t matter if you get a one-dose or two-dose COVID-19 vaccine. “We don’t look at frequency as a way to evaluate the effectiveness of a vaccine,” Dr. Wolfe said. “Each has been shown to stimulate your immune system very effectively.”

Getting a one-dose vaccine has one obvious advantage: you don’t have to worry about scheduling a second appointment. It’s a great option for people anxious about needle pricks too.

COVID-19 Vaccines Have Similar Side Effects

All three vaccines may cause mild to moderate side effects that are also associated with other types of vaccines. They include redness, swelling, and pain at the injection site, fever, fatigue, headache, chills, nausea, vomiting, diarrhea, muscle pain, and/or joint pain.

The J&J Vaccine Protects You from COVID-19

The clinical trials showed that the Moderna and Pfizer vaccines provide equal protection (95% for Pfizer and 94% for Moderna). The J&J vaccine is slightly less effective (67%) against mild to moderate disease. This may be due to the population that was vaccinated and the sites across the world where those studies took place.

The J&J Vaccine Is Safe

The clinical trial data show all three vaccines are safe for adults -- 18 and older -- and across different ethnic and racial groups. The J&J vaccine was tested in more people who identified as Hispanic/Latino and Black or African American. It was also tested in more people who were 60 years or older and in those who had conditions such as heart disease, obesity, and diabetes. While the vaccine was shown to be less effective in people with chronic medical conditions, Dr. Wolfe stressed that the vaccine still reduces the risk of getting severe COVID-19 in this at-risk population.

COVID-19 Vaccines Are Not Available for Children

Children under age 18 were not included in the J&J and Moderna trials and are not eligible for vaccination. Children 12 and older can receive the Pfizer vaccine. J&J is planning to study the vaccine in children younger than 18. Pfizer and Moderna studies in children are underway.

If You're Pregnant or Breastfeeding, Talk to Your Doctor

People who were pregnant or breastfeeding were not included in any COVID-19 vaccine trials; however, pregnant and breastfeeding people can get the vaccines. “We recommend you talk to your doctor,” Dr. Wolfe said. “The vaccines offer you protection from COVID-19, which can be a serious concern for you and your child. We want you to make the choice that’s best for you,” he said.

Don’t Change Your Behavior Once You Are Vaccinated

“None of the vaccines are 100% effective at preventing COVID-19,” Dr. Wolfe explained. “Even after being vaccinated, washing your hands, wearing a mask, and practicing physical distancing will keep all of us safe and help end this pandemic."