The COVID-19 vaccine works similarly to other vaccines your child or teen may have had. Germs such as SARS-CoV-2, the virus that causes COVID-19, invade and multiply inside the body. The vaccine stops this by teaching the immune system to recognize and make antibodies to fight the virus. After vaccination, your child or teen has less of a chance of getting COVID-19. If they do get infected with the virus, they may not be as sick as they would without the vaccine.