What you should know about COVID-19 Vaccine and Boosters
COVID-19 vaccines are effective at helping protect against severe disease and death from variants of the virus that causes COVID-19 currently circulating, including the Delta variant. Vaccines are widely accessible in the United States at no cost. Everyone aged 5 years and older should get a COVID-19 vaccination as soon as possible. These vaccines are effective at keeping people from getting COVID-19, getting very sick, and dying.
HOW COVID-19 VACCINES WORK
COVID-19 vaccines teach our immune systems how to recognize and fight the virus that causes COVID-19. It typically takes 2 weeks after vaccination for the body to build protection (immunity) against the virus that causes COVID-19. That means it is possible a person could still get COVID-19 before or just after vaccination and then get sick because the vaccine did not have enough time to build protection. People are considered fully vaccinated 2 weeks after their second dose of the Pfizer-BioNTech or Moderna COVID-19 vaccines, or 2 weeks after the single-dose Johnson & Johnson’s Janssen COVID-19 vaccine.
People with moderately to severely compromised immune systems should receive an additional dose of mRNA COVID-19 vaccine after the initial 2 doses of either Pfizer or Moderna.
Learn more about how COVID-19 mRNA vaccines work.
TYPES OF VACCINES
Currently, there are three main types of COVID-19 vaccines in the United States. Below is a description of how each type of vaccine prompts our bodies to recognize and protect us from the virus that causes COVID-19. None of these vaccines can give you COVID-19.
- mRNA vaccines contain material 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 T-lymphocytes and B-lymphocytes that will remember how to fight the virus that causes COVID-19 if we are infected in the future.
- Protein subunit vaccines include harmless pieces (proteins) of the virus that cause COVID-19 instead of the entire germ. Once vaccinated, our immune system recognizes that the proteins don’t belong in the body and begins making T-lymphocytes and antibodies. If we are ever infected in the future, memory cells will recognize and fight the virus.
- Vector vaccines contain a weakened version of a live virus—a different virus than the one that causes COVID-19—that has genetic material from the virus that causes COVID-19 inserted in it (this is called a viral vector). Once the viral vector is inside our cells, the genetic material gives cells instructions to make a protein that is unique to the virus that causes COVID-19. Using these instructions, our cells make copies of the protein. This prompts our bodies to build T-lymphocytes and B-lymphocytes that will remember how to fight that virus if we are infected in the future.
Who should get a booster dose?
People who are recommended to get booster doses should have received their second dose of Pfizer vaccine at least five months ago and are either: There are no booster shots for Moderna or John and Johnson yet.
- 12 or older or live in a nursing home, or
- Are aged 50-64 with underlying medical conditions that put them at risk of serious complications from COVID-19.
The CDC also said that some other higher-risk people should consider getting a booster dose of Pfizer vaccine at least five months after their second dose. These people include:
- People who are age 18 and older who have underlying medical conditions, and
- People who work in higher-risk jobs like healthcare workers, teachers, or in other higher-risk occupational or institutional settings.
Separately, some people 5 or older with certain immunosuppressing conditions who were vaccinated with Pfizer or Moderna should get an additional dose 28 days after their second dose.