Johnson & Johnson’s Janssen COVID-19 Vaccine Overview and Safety
Johnson & Johnson’s Janssen COVID-19 Vaccine: CDC and FDA have recommended that use of Johnson & Johnson’s Janssen (J&J/Janssen) COVID-19 Vaccine resume in the United States, effective April 23, 2021. However, women younger than 50 years old especially should be aware of the rare risk of blood clots with low platelets after vaccination, and that other COVID-19 vaccines are available where this risk has not been seen. If you received a J&J/Janssen vaccine, here is what you need to know. Read the CDC/FDA statement.
Manufacturer: Janssen Pharmaceuticals Companies of Johnson & Johnson
Type of Vaccine: Viral Vector
Number of Shots: 1 shot
How Given: Shot in the muscle of the upper arm
Does NOT Contain: Eggs, preservatives, latex
Full List of Ingredients [PDF – 6 pages]external icon
- The J&J/Janssen vaccine is recommended for people aged 18 years and older.
- Learn more about how CDC is making COVID-19 vaccine recommendations and CDC’s vaccine rollout recommendations
- If you have had a severe allergic reaction (anaphylaxis) or an immediate allergic reaction—even if it was not severe—to any ingredientexternal icon in the J&J/Janssen COVID-19 vaccine (such as polysorbate), you should not get the J&J/Janssen COVID-19 vaccine.
- An allergic reaction is considered severe when a person needs to be treated with epinephrine or EpiPen© or if they must go to the hospital. Experts refer to severe allergic reactions as anaphylaxis. Learn about common side effects of COVID-19 vaccines and when to call a doctor.
- An immediate allergic reaction means a reaction within 4 hours of getting vaccinated, including symptoms such as hives, swelling, or wheezing (respiratory distress).
If you aren’t able to get the J&J/Janssen COVID-19 vaccine, you may still be able to get a different type of COVID-19 vaccine. Learn more information for people with allergies.
Possible Side Effects
In the arm where you got the shot:
Throughout the rest of your body:
- Muscle pain
These side effects usually start within a day or two of getting the vaccine. Side effects might affect your ability to do daily activities, but they should go away in a few days.
Fainting After Vaccination
Fainting (syncope) and other events that may be related to anxiety like rapid breathing, low blood pressure, numbness, or tingling can happen after getting any vaccine. Although uncommon, these events are not unexpected, and they are generally not serious.
According to information from the Vaccine Adverse Event Reporting System (VAERS),there have been 653 reports of fainting events(fainting and near-fainting) among nearly 8 million doses of J&J/Janssen vaccine administered in the United States in March and April 2021. This translates to a rate of about 8 fainting events for every 100,000 doses of the J&J/Janssen COVID-19 vaccine given. These events occurred during the recommended 15-minute wait after vaccination. It’s not clear at this time whether these events were associated with the vaccine or with anxiety, possibly related to preexisting concerns some people who chose to get the one-dose J&J/Janssen vaccine may have about needles or shots.
By comparison, the rate of fainting after flu vaccination in 2019-2020 was 0.05 per 100,000 doses. The Pfizer-BioNTech and Moderna vaccines do not seem to have higher rates of fainting events, but there is currently an ongoing in-depth review of non-serious adverse event reports, including fainting, among people receiving mRNA COVID-19 vaccines.
You should get the first COVID-19 vaccine that is available to you. Do not wait for a specific brand. All currently authorized and recommended COVID-19 vaccines are safe and effective, and CDC does not recommend one vaccine over another.
Safety Data Summary
- In clinical trials, side effects were common within 7 days of getting vaccinated but were mostly mild to moderate.
- Side effects were more common in people 18–59 years old compared to people 60 years and older.
- CDC will continue to provide updates as we learn more about the safety of the J&J/Janssen vaccine in real-world conditions.
Learn more about vaccine safety monitoring after a vaccine is authorized or approved for use.
- The J&J/Janssen vaccine was 66.3% effective in clinical trials (efficacy) at preventing laboratory-confirmed COVID-19 illness in people who had no evidence of prior infection 2 weeks after receiving the vaccine. People had the most protection 2 weeks after getting vaccinated.
- The vaccine had high efficacy at preventing hospitalization and death in people who did get sick. No one who got COVID-19 at least 4 weeks after receiving the J&J/Janssen vaccine had to be hospitalized.
- Early evidence suggests that the J&J/Janssen vaccine might provide protection against asymptomatic infection, which is when a person is infected by the virus that causes COVID-19 but does not get sick.
- CDC will continue to provide updates as we learn more about how well the J&J/Janssen vaccine works in real-world conditions.
Clinical Trial Demographic Information
Clinical trials for the J&J/Janssen vaccine included people from the following racial and ethnic categories:
- 62.1% White
- 17.2% Black or African American
- 8.3% American Indian or Alaska Native
- 5.4% Multiple races
- 3.5% Asian
- 0.3% Native Hawaiian or other Pacific Islander
- 45.1% Hispanic or Latino
- 52.4% Not Hispanic or Latino
- 2.5% Unknown
- 55.5% Male
- 44.5% Female
- <0.1% Undifferentiated or unknown sex
- 66.5% 18–59 years
- 33.5% 60 years and older
- 19.6% 65 years and older
- 3.5% 75 years and older