Vector vaccine

In this type of vaccine, material from the virus that causes COVID-19 is placed in a modified version of a different virus. This different virus is called a viral vector. The viral vector gives cells instructions to make copies of the COVID-19 virus S protein.

Once the cells display the S proteins on their surfaces, the immune system responds by creating antibodies and defensive white blood cells. If infection with the virus that causes COVID-19 happens later, the antibodies help clear out the virus.

Viral vector vaccines can't cause infection with the COVID-19 virus or the viral vector virus. The Johnson & Johnson COVID-19 vaccine is a vector vaccine that's no longer used in the United States.