Each vaccine sponsored by HHS’s Operation Warp Speed uses a slightly different approach with the same goal: to induce an immune response in the body against SARS-CoV2, the virus that causes COVID-19. The first two vaccines likely to be available, from Pfizer and Moderna, are mRNA vaccines.
mRNA vaccines contain a message from the virus that causes COVID-19 that gives our cells instructions for how to make a harmless protein that is unique to the virus. After our cells make copies of the protein, they destroy the genetic material from the vaccine. Our bodies recognize that the protein should not be there and build immune cells that will remember how to fight the virus that causes COVID-19 if we are infected in the future.
Most of the vaccines will require two shots, with the second shot received 21 to 28 days after the first, depending on the vaccine.