Johnson & Johnson COVID-19 Vaccine

Frequently Asked Questions


The Washington State Department of Health distributes vaccine dosages to sites across the state. If UW Medicine receives an allotment of the Johnson & Johnson vaccine, we will administer the vaccine based on state guidelines for eligibility.


The Johnson & Johnson vaccine, like the Pfizer and Moderna vaccines, is very effective. All three vaccines prevent severe illness, hospitalization and death.


The Johnson & Johnson vaccine is an adenovirus-based vaccine. It was shown to be effective after a single dose in clinical trials. The Pfizer and Moderna COVID-19 vaccines are mRNA vaccines and were administered twice in clinical trials. The Johnson & Johnson vaccine can be refrigerated and does not require deep freezer storage like the Pfizer and Moderna vaccines.


Yes, it is highly effective in preventing severe COVID-19 disease caused by new variants. For example, a study showed the vaccine was 82% effective after 28 days in preventing severe infection from the South Africa variant. It is estimated more than 90% of the infections in South Africa at the time of the study were caused by variants. People who were vaccinated had milder cases of COVID-19 than those who were not vaccinated.


No serious side effects or allergic reactions have been reported with the Johnson & Johnson vaccine. During clinical trials, participants experienced mild side effects, including injection site pain, headache, fatigue and muscle pain.

Please let your provider know if you suffer from severe allergic reactions and consider scheduling a day off after your vaccination in case you are feeling unwell.