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COVID-19 vaccines

Vaccines for COVID-19; COVID - 19 vaccinations; COVID-19 shots; Vaccinations for COVID-19; COVID-19 immunizations; COVID-19 prevention - vaccines; mRNA vaccine - COVID; COVID-19 vaccine booster shots; Booster shots for COVID-19

COVID-19 vaccines are used to prepare the body's immune system to protect against COVID-19. These vaccines are a vital tool to help stop the COVID-19 pandemic.

Everyone ages 6 months and older should get a free COVID-19 vaccination. This includes people who are pregnant and those planning to become pregnant. You should get a COVID-19 vaccine even if you have already had COVID-19.


COVID-19 vaccine
Arm Rash After COVID-19 Vaccination

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COVID-19 vaccines protect people from getting COVID-19 and from getting more severe symptoms if they get COVID-19. These vaccines "teach" your body how to defend against the SARS-CoV-2 virus, which causes COVID-19.

COVID-19 vaccines have been shown to do a very good job of:


The preferred COVID-19 vaccines approved in the United States are called mRNA vaccines. They work differently from many other vaccines.

The COVID-19 mRNA vaccine is given as an injection (shot) in the arm in 2 doses.

People who have a weak immune system (immunocompromised) should get an additional dose at least 28 days after their second shot of either the Pfizer-BioNTech or Moderna mRNA vaccine. This includes people receiving certain types of cancer treatment and people taking medicines that suppress the immune system. Ask your doctor if you are not sure. Getting a third dose will improve the response to the vaccine in people with weak immune systems.

Children ages 6 months to age 17 years can get either the Pfizer-BioNTech or the Moderna vaccine. These are the only vaccines available to this age group at this time. The COVID-19 vaccine given to children and teens has the same active ingredients as the vaccine given to adults. Dosage is based on the child's age on the day of vaccination. It is not based on the child's size or weight.

It takes time for your child's immune system to start protecting them after receiving the vaccine. Children are considered fully vaccinated 2 weeks after receiving the last shot in the vaccine series.


The Novavax vaccine is a protein subunit vaccine. The vaccine includes harmless pieces of the "spike" protein that causes COVID-19. The vaccine triggers the body to develop antibodies to protect you from the virus.

The Novavax vaccine is given as an injection (shot) in the arm in 2 doses, given 3 to 8 weeks apart.

The Johnson and Johnson's Janssen (J&J/Janssen) COVID-19 vaccine is a viral vector vaccine. It is given as one shot. It has been approved for use in the United States in some cases:

It takes time for your immune system to start protecting you after receiving the vaccine. You are considered fully vaccinated:


COVID-19 vaccines:

To get up-to-date accurate information about COVID-19 vaccines, go to the Centers for Disease Control and Prevention (CDC) website:


While COVID-19 vaccines will not make you sick, they may cause certain side effects and flu-like symptoms. This is normal. These symptoms are a sign that your body is making antibodies against the virus. Common side effects include:

Side effects from the shot may affect your ability to do daily activities, but they will go away in a few days. Even if you have side effects, you should get the second shot. Any side effects from the vaccine are far less dangerous than the potential for serious illness or death from COVID-19.


There are several ways you can look for vaccination providers near you.

Learn what to expect when you get your COVID-19 vaccine.


The safety of vaccines is the top priority, and COVID-19 vaccines have passed rigorous safety standards before approval. Millions of people have received the vaccine, and no long-term side effects have been reported. They continue to be closely monitored to ensure they are safe and effective.

There have been reports of some people who have had an allergic reaction to the current vaccines. So it is important to follow certain precautions:

If you have had an allergic reaction, even if not severe, to other vaccines or injectable therapies, you should ask your doctor if you should get a COVID-19 vaccine. Your doctor will help you decide if it is safe to get vaccinated.

Adverse events after COVID-19 vaccination are very rare.

All these associations are so rare that they should not cause hesitation in receiving any of these vaccines.

CDC recommends that people may still get vaccinated if they have a history of:

To learn more about COVID-19 vaccine safety, go to the CDC website:


Over time, COVID-19 vaccines appear to become less protective against the virus. Getting a booster dose helps provide additional protection against COVID-19. As a result, a booster shot is now recommended for all people age 18 years and older.

If you received the Pfizer-BioNTech or Moderna mRNA vaccine, you can get a booster dose 5 months after receiving your second dose of the initial vaccine.

If you received the J&J/Janssen vaccine, you can get a booster dose 2 months after receiving your initial vaccine.

It is recommended to get an mRNA vaccine (Pfizer-BioNTech or Moderna) for your booster dose, regardless of which vaccine you first received. People ages 5 to 17 years can get the Pfizer-BioNTech vaccine as the booster dose.

Adults ages 50 years and older and people who are immunocompromised can get a second booster dose (Pfizer-BioNTech or Moderna) at least 4 months after the 1st booster dose.

Novavax is not authorized for use as a booster at this time.  

The CDC has further information about COVID-19 vaccine booster shots.


We are still learning how well vaccines help prevent COVID-19 from spreading and how long the protection they provide lasts. Until more is known, using vaccines, masks, and taking other steps to help protect yourself and others is the best way to stay safe and healthy.


Centers for Disease Control and Prevention website. Benefits of getting a COVID-19 vaccine. Updated August 17, 2022. Accessed August 18, 2022.

Centers for Disease Control and Prevention website. COVID-19 vaccines for children and teens. Updated July 21, 2022. Accessed August 15, 2022.

Centers for Disease Control and Prevention website. COVID-19 vaccines for moderately to severely immunocompromised people. Updated July 20, 2022. Accessed August 15, 2022.

Centers for Disease Control and Prevention website. COVID-19 vaccines for people who would like to have a baby. Updated July 14, 2022. Accessed August 15, 2022.

Centers for Disease Control and Prevention website. Stay up to date with your COVID-19 vaccines. Updated August 19, 2022. Accessed August 19, 2022.

Centers for Disease Control and Prevention website. Use of COVID-19 vaccines in the United States. Interim clinical considerations. Updated July 20, 2022. Accessed August 15, 2022.

Centers for Disease Control and Prevention website. Myths and facts about COVID-19 vaccines. Updated July 20, 2022. Accessed August 15, 2022.

Centers for Disease Control and Prevention website. Allergic reactions after COVID-19 vaccination. Updated July 20, 2022. Accessed August 15, 2022.

Centers for Disease Control and Prevention website. COVID-19 vaccine boosters. Updated July 20, 2022. Accessed August 15, 2022.

Center for Disease Control and Prevention website. COVID-19: Selected adverse events reported after COVID-19 vaccination. Updated August 15, 2022. Accessed August 15, 2022.


Review Date: 8/5/2022  

Reviewed By: Frank D. Brodkey, MD, FCCM, Associate Professor, Section of Pulmonary and Critical Care Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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