When we get a vaccine, it activates our immune response. This helps our bodies learn to fight off the virus without the danger of an actual infection. If we are exposed to the virus in the future, our immune system “remembers” how to fight it. All authorized COVID-19 vaccines provide strong protection against serious illness and hospitalization due to COVID.

The Moderna and Pfizer vaccines use messenger RNA, or mRNA. mRNA vaccines do not contain a live virus. They give our bodies “instructions” for how to make the spike-shaped proteins that are on the outside of the virus — harmless when by themselves — which gives our bodies the opportunity to learn how to fight off those very same proteins on the real virus. While these vaccines use newer technology, researchers have been studying mRNA for decades.

Johnson & Johnson’s vaccine is a viral vector vaccine and also does not contain a live virus. It uses a harmless adenovirus to create a spike-shaped protein that the immune system responds to, creating antibodies to protect against COVID.

It takes time for your body to strengthen its defenses after vaccination, so you won’t have the full benefit of the vaccine until 2 weeks after your final dose.

SOURCE: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html (CDC)

Updated 12/16/2021