Experts do not yet know what percentage of people would need to get vaccinated to achieve herd immunity to COVID-19. Herd immunity means that enough people in a community are protected from getting a disease because they’ve already had the disease or they’ve been vaccinated. Herd immunity makes it hard for the disease to spread from person to person, and it even protects those who cannot be vaccinated, like newborns. The percentage of people who need to have protection in order to achieve herd immunity varies by disease. CDC and other experts are studying herd immunity and will provide more information as it is available.

The two COVID-19 vaccines currently available in the United States do not contain eggs, preservatives, or latex. For a full list of ingredients, please see each vaccine’s Fact Sheet for Recipients and Caregivers:

• Pfizer-BioNTech COVID-19
• Moderna COVID-19

Vaccine doses purchased with U.S. taxpayer dollars will be given to the American people at no cost. However, vaccination providers can charge an administration fee for giving someone the shot. Vaccination providers can be reimbursed for this by the patient’s public or private insurance company or, for uninsured patients, by the Health Resources and Services Administration’s Provider Relief Fund. No one can be denied a vaccine if they are unable to pay the vaccine administration fee.

When the Food and Drug Administration authorizes or approves a new COVID-19 vaccine, the Advisory Committee on Immunization Practices (ACIP)quickly holds a public meeting to vote on whether to recommend the vaccine. Based on input from ACIP, CDC then publishes vaccine recommendations in the Morbidity and Mortality Weekly Report.

ACIP and CDC are also making recommendations for who should be offered COVID-19 vaccine first when supplies are limited. While CDC makes recommendations for who should be offered COVID-19 vaccine first, each state has its own plan for vaccine prioritization, distribution, and allocation. Please contact your state health department for more information on its plan for COVID-19 vaccination.

All the COVID-19 vaccines being used have gone through rigorous studies to ensure they are as safe as possible. Systems that allow CDC to watch for safety issues are in place across the entire country.

The U.S. Food and Drug Administration (FDA) has granted Emergency Use Authorizations for COVID-19 vaccines that have been shown to meet rigorous safety criteria and be effective as determined by data from the manufacturers and findings from large clinical trials. Watch a video describing the emergency use authorization. Clinical trials for all vaccines must first show they meet rigorous criteria for safety and effectiveness before any vaccine, including COVID-19 vaccines, can be authorized or approved for use. The known and potential benefits of a COVID-19 vaccine must outweigh the known and potential risks of the vaccine. Learn more about how federal partners are ensuring the safety of COVID-19 vaccines in the United States.

People  who are pregnant and part of a group recommended to receive the COVID-19 vaccine may choose to be vaccinated. If you have questions about getting vaccinated, talking with a healthcare provider may might help you make an informed decision. While breastfeeding is an important consideration, it is rarely a safety concern with vaccines.

No data are available yet on the safety of COVID-19 vaccines in lactating women or on the effects of mRNA vaccines on breastfed infants or on milk production/excretion. mRNA vaccines are not thought to be a risk to breastfeeding infants. People who are breastfeeding and are part of a group recommended to receive a COVID-19 vaccine, such as healthcare personnel, may choose to be vaccinated.

To make sure that more information is gathered regarding the safety of these vaccines when administered during pregnancy, pregnant people are encouraged to enroll in v-safe, CDC’s new smartphone-based tool being used to check-in on people’s health after they receive a COVID-19 vaccine. If pregnant people report health events through v-safe after vaccination, someone from CDC may call to check on them and get more information. Additionally, pregnant people enrolled in v-safe will be contacted by CDC and asked to participate in a pregnancy registry that will monitor them through pregnancy and the first 3 months of infancy. Learn more about COVID-19 vaccination considerations for people who are pregnant or breastfeeding.

People with underlying medical conditions can receive the FDA-authorized COVID-19 vaccines provided they have not had an immediate or severe allergic reaction to a COVID-19 vaccine or to any of the ingredients in the vaccine. Learn more about vaccination considerations for persons with underlying medical conditions. Vaccination is an important consideration for adults of any age with certain underlying medical conditions because they are at increased risk for severe illness from the virus that causes COVID-19.

Serious problems from vaccination can happen, but they are rare. CDC has learned of reports that some people have experienced severe allergic reactions—also known as anaphylaxis—after getting a COVID-19 vaccine. As an example, an allergic reaction is considered severe when a person needs to be treated with epinephrine or EpiPen^© or if they must go to the hospital. Learn more about COVID-19 vaccines and allergies.

​If you get a COVID-19 vaccine and you think you might be having a severe allergic reaction after leaving the vaccination site, seek immediate medical care by calling 911.

You can report side effects and reactions using either v-safe or the Vaccine Adverse Event Reporting System (VAERS.)

• V-safe is a new smartphone-based, after-vaccination health checker for people who receive COVID-19 vaccines. V-safe uses text messaging and web surveys from CDC to check in with vaccine recipients following COVID-19 vaccination. V-safe also provides second vaccine dose reminders if needed, and telephone follow up to anyone who reports medically significant (important) adverse events.
• Vaccine Adverse Event Reporting System (VAERS)external icon is the national system that collects reports from healthcare professionals, vaccine manufacturers, and the public of adverse events that happen after vaccination; reports of adverse events that are unexpected, appear to happen more often than expected, or have unusual patterns are followed up with specific studies. Reports to VAERS help CDC monitor the safety of vaccines. If experts detect an unexpected adverse event, they quickly study it further to assess whether it is a true safety concern. Experts then decide whether changes are needed in U.S. vaccine recommendations. This monitoring is critical to help ensure that the benefits continue to outweigh the risks for people who receive vaccines.

Healthcare providers will be required to report certain adverse events following vaccination to VAERS. Healthcare providers also have to adhere to any revised safety reporting requirements according to FDA’s conditions of authorized use throughout the duration of any Emergency Use Authorization; these requirements would be posted on FDA’s website external icon.

You can expect normal side effects after you are vaccinated. Refer to What to Expect at Your Appointment to Get Vaccinated for COVID-19 for additional information.

To protect yourself, follow these recommendations:

• Wear a mask over your nose and mouth
• Stay at least 6 feet away from others
• Avoid crowds
• Avoid poorly ventilated spaces
• Wash your hands often

Yes. Due to the severe health risks associated with COVID-19 and the fact that reinfection with COVID-19 is possible, you should be vaccinated regardless of whether you already had COVID-19 infection. If you were treated for COVID-19 symptoms with monoclonal antibodies or convalescent plasma, you should wait 90 days before getting a COVID-19 vaccine. Talk to your doctor if you are unsure what treatments you received or if you have more questions about getting a COVID-19 vaccine.

Experts do not yet know how long someone is protected from getting sick again after recovering from COVID-19. The immunity someone gains from having an infection, called “natural immunity,” varies from person to person.  It is rare for someone who has had COVID-19 to get infected again. It also is uncommon for people who do get COVID-19 again to get it within 90 days of when they recovered from their first infection.  We won’t know how long immunity produced by vaccination lasts until we have more data on how well the vaccines work.

Both natural immunity and vaccine-induced immunity are important aspects of COVID-19 that experts are working to learn more about, and CDC will keep the public informed as new evidence becomes available.

The federal government does not mandate (require) vaccination for individuals. For some healthcare workers or essential employees, a state or local government or employer, for example, may require or mandate that workers be vaccinated as a matter of state or other law. Check with your employer to see if they have any rules that apply to you.

The California Department of Public Health has dropped the COVID-19 mask and vaccination mandates for health care settings. Beginning April 3, 2023, health care workers, patients and visitors will no longer be required to wear a mask or be vaccinated to work in facilities that include hospitals, urgent care centers and dental and doctors’ offices.