Key Things to Know About COVID-19 Vaccines

COVID-19 vaccines are effective at helping protect against severe disease and death, including from currently circulating variants of the virus that causes COVID-19 (e.g., the coronavirus Delta variant). If you are fully vaccinated, you can resume activities that you did before the pandemic. However, you should wear a mask indoors in public if you are in an area of substantial or high transmission. Being fully vaccinated and wearing a mask maximizes protection from the Delta variant and possibly spreading it to others.

You may have side effects after vaccination. These are normal and should go away within a few days. Everyone aged 12 years and older is recommended to get vaccinated. People who are moderately to severely immunocompromised are recommended to get an additional dose of an mRNA COVID-19 vaccine (i.e., Pfizer-BioNTech or Moderna). Certain groups of people are recommended to get a Pfizer-BioNTech booster shot. Keep reading to learn more about COVID-19 vaccines.

Availability of Vaccines

COVID-19 vaccines are widely accessible in the United States. Everyone aged 12 years and older should get a COVID-19 vaccination as soon as possible. COVID-19 vaccines are available for everyone at no cost. Many doctors’ offices, retail pharmacies, hospitals and clinics offer COVID-19 vaccinations. Parents should check with their children’s health care provider about whether they offer COVID-19 vaccination. Click here to learn how to find a COVID-19 vaccine.


COVID-19 vaccines are effective at protecting you from COVID-19, especially severe illness and death. COVID-19 vaccines can reduce the risk of people spreading the virus that causes COVID-19. If you are fully vaccinated, you can resume activities that you did before the pandemic. This resource outlines what you can do when you have been fully vaccinated.

Studies show that COVID-19 vaccines are effective, especially at keeping you from getting seriously ill, even if you do get COVID-19. Click here to learn more about the benefits of getting vaccinated. COVID-19 vaccines teach our immune systems how to recognize and fight the virus that causes COVID-19. It typically takes two 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 two weeks after their second dose of the Pfizer-BioNTech or Moderna COVID-19 vaccines or two weeks after the single-dose Johnson & Johnson’s Janssen COVID-19 vaccine. To receive the most protection, people should receive all recommended doses of a COVID-19 vaccine. Certain groups of people are recommended to get either an additional dose or a booster dose.

People can sometimes get COVID-19 after being fully vaccinated. However, this only happens in a small proportion of people, even with the Delta variant. When these infections occur among vaccinated people, they tend to be mild. For more information about the effectiveness of COVID-19 vaccines, click here.


Millions of people in the United States have received COVID-19 vaccines, and these vaccines have undergone and continue to undergo the most intensive safety monitoring in U.S. history. This monitoring includes using both established and new safety monitoring systems to make sure that COVID-19 vaccines are safe. COVID-19 vaccines cannot give you COVID-19. This resource can help you bust the myths and learn the facts about COVID-19 vaccines.

The Centers for Disease Control and Prevention (CDC) has developed a new tool, v-safe, to help quickly find any safety issues with COVID-19 vaccines. V-safe is a smartphone-based, after-vaccination health checker for people who receive COVID-19 vaccines. Click here to learn how the federal government is working to ensure the safety of COVID-19 vaccines. While COVID-19 vaccines were developed rapidly, all steps have been taken to ensure their safety and effectiveness.

After COVID-19 vaccination, you may have some side effects. These are normal signs that your body is building protection. The side effects from COVID-19 vaccination, such as tiredness, headache or chills, may affect your ability to do daily activities, but they should go away within a few days. Click here to learn more about what to expect after getting vaccinated.

Population Immunity

Population immunity, also known as herd immunity or community immunity, means that enough people in a community are protected from getting a disease because they’ve already had the disease or because they’ve been vaccinated.

Population immunity makes it hard for a disease to spread from person to person. It even protects those who cannot be vaccinated, like newborns or people who are allergic to a vaccine. The percentage of people who need to have protection to achieve population immunity varies by disease.

It’s unclear how many people need to be vaccinated against COVID-19 before the population can be considered protected. The CDC will continue to update its recommendations for both vaccinated and unvaccinated people.

Variants and Vaccines

COVID-19 vaccines approved or authorized by the U.S. Food and Drug Administration help protect against Delta and other known variants. These vaccines are especially effective at keeping people from getting very sick or dying from COVID-19. To maximize protection against the Delta variant and prevent possibly spreading it to others, you should wear a mask indoors in public if you are in an area of substantial or high transmission even if you are fully vaccinated. It’s unclear how effective the vaccines will be against new variants that may arise.

Source: CDC