COVID-19 Q&A: Johnson & Johnson Vaccine

Idaho received 13,300 doses of the Johnson & Johnson’s Janssen vaccine the week of March 1. We are not expecting additional shipments of the vaccine until late March, based on information from the manufacturer and the federal government. It was approved under Emergency Use Authorization on Feb. 27, 2021. On Feb. 28, the Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices (ACIP) recommended use of the vaccine in people 18 years and older.

Adding Johnson and Johnson’s vaccine to our toolbox means more people can get vaccinated, which increases the overall population protected from severe disease, hospitalization, and even death.

Having different types of vaccines available for use, especially ones with different dosing recommendations and storage and handling requirements, can offer more options and flexibility for the public and vaccine providers.

Is the Johnson & Johnson vaccine an mRNA vaccine like Pfizer and Moderna?

The Johnson & Johnson vaccine is a single-dose recombinant (combined genetic material) vector (vehicle) vaccine. Recombinant vaccines use one virus to carry a small piece of genetic material from another virus to trigger an immune response in the body. The Johnson & Johnson vaccine uses a modified adenovirus to carry the gene for the SARS-CoV-2 (the virus that causes COVID-19) spike protein genetic material. The virus can enter cells but can’t replicate inside them or cause illness. The body’s immune system detects the SARS-CoV-2 spike protein and generates antibodies. 

It does not require ultra-cold storage, like the Pfizer and Moderna vaccines do. Storage and handling of this vaccine is similar to many other vaccines. It must be stored at refrigerated temperatures between 36°- 46°F (2°-8°C). It is easy to transport and store and allows for expanded availability in most community settings and mobile sites, as supply scales up.

How well does it prevent infection with the virus that causes COVID-19?

During clinical trials, the Johnson & Johnson COVID-19 vaccine was 85 percent effective in preventing severe disease 28 days after vaccination in all adults 18 years and older, across all regions studied (United States, Central and South America, and South Africa). Efficacy against severe disease increased over time with no severe cases reported among vaccinated participants after day 49.

The vaccine also demonstrated complete protection against COVID-related hospitalization and death, 28 days after vaccination. Protection was generally consistent across race, age groups, and SARS-CoV-2 variants. The vaccine has a reported 66 percent efficacy against preventing moderate disease.

Is it safe?

During the studies, there were no significant safety concerns reported. Overall, serious adverse events reported were similar in study participants who received the placebo when compared with participants who received the vaccine.

What are the side effects for people who get the vaccine?

Common reactions to the vaccine included injection site pain, fatigue, headache, and muscle aches.

How does it compare to the Pfizer and Moderna vaccines for preventing COVID-19?

The different types of vaccines were studied under different conditions and in different countries, during different times in the pandemic; therefore, you can’t directly compare how well they work. It is recommended to get whichever COVID-19 vaccine is available to you – it is the best way to protect yourself from serious illness.

To slow the spread of COVID-19 in Idaho, please continue to:


Stay up-to-date with the latest and most accurate information on COVID-19 at the following websites:

DHW also posts lots of information, including daily updates on the numbers on Twitter, Facebook, and Instagram.

Dr. Christine Hahn is the state’s epidemiologist and the Division of Public Health’s medical director. She is board certified in infectious disease and works in the Family Medicine Residency of Idaho’s tuberculosis clinic twice monthly. She also serves on CDC’s Advisory Committee on Immunization Practices, and since late February 2020, has been focusing almost solely on responding to the coronavirus pandemic.

The Idaho Department of Health and Welfare is dedicated to strengthening the health, safety, and independence of Idahoans. Learn more at

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