Both of these vaccines are viral vector-based vaccines. They use a harmless virus, such as an adenovirus, as a delivery system. When a person is given the vaccine, the vector virus contained within the vaccine produces the SARS-COV-2 spike protein. This protein is found on the surface of the virus that causes COVID-19 infection. This protein will not cause COVID-19 infection or make the individual sick. Through this process, the body is able to build a strong immune response against the spike protein without exposing you to the virus that causes COVID-19 infection.