Johnson & Johnson, best known for Band-Aids and no-tears baby shampoo, is seeking U.S. Emergency Use Authorization for its COVID-19 vaccine this month.

Once authorized, the J&J vaccine will be the only COVID-19 vaccine available in the United States that requires a single dose. It’s a different kind of vaccine than the mRNA vaccines produced by Pfizer and Moderna.

The J&J vaccine is rather clever. To start with, the vaccine utilizes a virus that is a cause of the common cold. It’s a good pick because even in its natural form, the virus only triggers a minor respiratory illness. Normally, this virus enters a cell and deposits its DNA. This DNA serves as the blueprint for converting the cell into a virus-producing factory.

Once hundreds of viruses are made, the cell breaks open and releases them. These viruses infect other cells and can infect other people when sent flying by coughing or sneezing. To make the vaccine virus safer, scientists removed parts of its DNA blueprint necessary for it to multiply. This keeps vaccinated people from developing cold symptoms and from spreading the vaccine virus to others.

Scientists then added a bit of DNA to the vaccine virus, which serves as the blueprint for the SARS-CoV-2 spike protein. Now, when the vaccine is injected into a muscle, the modified cold virus enters a cell and causes it to temporarily produce spike protein. The immune system recognizes the spike protein as foreign and in response produces immune cells and antibodies. These immune cells and antibodies provide protection against COVID-19.

All of us have had multiple colds. DNA-containing cold viruses don’t harm our DNA. The same can be said for the vaccine virus. Its DNA is short lived and doesn’t combine with or alter our DNA in any way.

It’s easy to imagine the J&J vaccine virus as a mail truck, which delivers to our cells the instructions for making different parts of germs. In fact, J&J has utilized this “mail truck” for other vaccines in human trials against Zika, RSV, HIV and Ebola.

Recently, the Ebola vaccine was authorized by the European Medicines Agency, the equivalent to our U.S. Food and Drug Administration. These investigational vaccines have been found safe and well tolerated in the more than 200,000 people who’ve received them. The J&J vaccine is safe even in immunocompromised individuals as the vaccine virus cannot replicate.

The vaccine is 72 percent effective in the United States in preventing moderate to severe COVID-19 infection. It is 85 percent effective at preventing hospitalization and 100 percent effective at preventing death. The fact that these numbers are less than those for the mRNA vaccines may lead the U.S. Centers for Disease Control and Prevention to make differential recommendations.

For example, the CDC may recommend preferential use of the J&J vaccine in individuals at lower risk from COVID-19 such as healthy young adults because their chance of hospitalization is extremely low. Those that find it hard to return for a second dose may find this “one-and-done” vaccine especially appealing.

Vaccine Smarts is written by Sealy Institute for Vaccine Sciences faculty members Drs. Megan Berman, an associate professor of internal medicine, and Richard Rupp, a professor of pediatrics at the University of Texas Medical Branch. For questions about vaccines, email

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