A New COVID-19 Vaccine: 10 Facts About the Johnson & Johnson Shot

COVID-19 vaccine needle in the bottle

Editor’s Note: Administration of the Johnson & Johnson vaccine was paused in Massachusetts on April 13 out of an abundance of caution so that federal health experts can review an extremely rare condition in 6 of the nearly 7 million people in the U.S. who received the J&J vaccine.

A new COVID-19 vaccine was authorized for use in the U.S., and it requires only a single dose. How does it work and how does it compare to the other vaccines that are currently available?

Here are 10 things to know about the Johnson & Johnson/Janssen vaccine:

  1. Johnson & Johnson’s new vaccine is the third vaccine to receive emergency use authorization from the Federal Drug Administration, and the first authorized vaccine to require only one shot.
  2. It’s highly effective at preventing severe disease, hospitalization and death from COVID-19. Clinical trials showed it is 100 percent effective at preventing hospitalization and death after 28 days, and 85 percent effective against preventing severe illness. Overall, the vaccine is 66 percent effective at preventing symptomatic disease. By comparison, flu vaccines are typically between 40 to 60 percent effective.
  3. Unlike the Pfizer and Moderna vaccines, which use messenger RNA, the Johnson & Johnson vaccine uses a common type of virus which has been modified so that it can’t replicate or reproduce and isn’t able to make you sick. It works to teach your own immune cells to recognize and attack COVID-19 to prevent infection. For this reason, the J&J vaccine isn’t considered a live-virus vaccine because it is not able to replicate and is safe for people even with weakened immune systems.
  4. While this COVID-19 vaccine is new, the technology is not. Adenoviruses have been in use for years during other viral outbreaks throughout the world including Ebola and Zika virus.
  5. This vaccine was developed in collaboration with Dan Barouch, MD, PhD, and Director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center, whose lab has also worked on vaccines for Ebola, among other viruses.
  6. Johnson & Johnson’s vaccine doesn’t need to be stored at extremely cold temperatures. Doctor’s offices, pharmacies, and public health clinics could potentially vaccinate and store the vaccine for months at normal refrigeration temperatures, making it much easier to use and distribute.
  7. The vaccine was tested against a number of new COVID-19 variants across the world — including those in South America and in South Africa — and has proven to be effective at preventing illness from these new strains.
  8. Vaccine recipients have reported mostly mild reactions after the shot, including a sore arm and a fever in less than 10 percent of participants. The other common side effects were muscle pain and a headache.
  9. A small study that was part of the trial links the vaccine to a 74 percent lower likelihood of asymptomatic transmission (over 71 days).
  10. After vaccination people will need to continue to wear masks, wash their hands frequently and maintain social distancing while we work towards herd immunity and learn more about the vaccine.