Frequently Asked Questions about COVID-19 Vaccination

While COVID-19 vaccines were developed rapidly, all steps were taken to make sure they are safe and effective:

• Approach to Development – Scientists have been working for many years to develop vaccines against viruses like the one that causes COVID-19. This knowledge helped speed up the initial development of the current COVID-19 vaccines.
• Clinical Trials – All vaccines in the United States must go through three phases of clinical trials to make sure they are safe and effective. During the development of COVID-19 vaccines, phases overlapped to speed up the process, but all phases were completed.
• Authorization or Approval – Before vaccines are available to people, the U.S. Food and Drug Administration (FDA) assesses the findings from clinical trials. FDA determined that three COVID-19 vaccines met FDA’s safety and effectiveness standards and granted those vaccines Emergency Use Authorizations (EUAs)external icon. This allowed the vaccines to be quickly distributed to control the pandemic. FDA has now granted full approval for Pfizer-BioNTech (COMIRNATY) COVID-19 vaccineexternal icon for people ages 16 years and older and for Moderna (Spikevax) COVID-19 vaccine for people ages 18 years and older.
• Manufacturing and Distribution – The U.S. government has invested substantial resources to manufacture and distribute COVID-19 vaccines. This allowed vaccine distribution to begin as soon as FDA authorized each vaccine.
• Tracking Safety Using Vaccine Monitoring Systems – COVID-19 vaccine safety monitoring has been the most intense and comprehensive in U.S. history. Hundreds of millions of people in the United States have received COVID-19 vaccines. Through several monitoring systems, CDC and FDA continue to provide updated information on the safety of these vaccines.

Learn more about developing COVID-19 vaccines.

Vaccine ingredients vary by manufacturer. None of the vaccines contain eggs, gelatin, latex, or preservatives. All COVID-19 vaccines are free from metals such as iron, nickel, cobalt, lithium, and rare earth alloys. They are also free from manufactured products such as microelectronics, electrodes, carbon nanotubes, or nanowire semiconductors.

To learn more about the ingredients in authorized COVID-19 vaccines, see

• Pfizer-BioNTech COVID-19 Vaccine Overview and Safety
• Moderna COVID-19 Vaccine Overview and Safety
• Johnson & Johnson’s Janssen COVID-19 Vaccine Overview and Safety
• Ingredients Included in COVID-19 Vaccines

Yes, COVID-19 vaccination is recommended for people who are pregnant, breastfeeding, trying to get pregnant now, or who might become pregnant in the future. You might want to have a conversation with your healthcare provider about COVID-19 vaccination. While such a conversation might be helpful, it is not required before vaccination. Learn more about vaccination considerations for people who are pregnant or breastfeeding.

If you are pregnant and have received a COVID-19 vaccine, we encourage you to enroll in v-safe, CDC’s smartphone-based tool that provides personalized health check-ins after vaccination. A v-safe pregnancy registry has been established to gather information on the health of pregnant people who have received a COVID-19 vaccine.

Vaccinating children ages 5 years and older can help protect them from getting COVID-19, spreading the virus to others, and getting sick if they do get infected. While COVID-19 tends to be milder in children than adults, it can make children very sick, require hospitalization, and some children have even died. Children with underlying medical conditions are more at risk for severe illness compared to children without underlying medical conditions.

Getting your child vaccinated helps to protect your child and your family, including siblings who are not eligible for vaccination and family members who may be at risk of getting very sick if infected. Vaccination is now recommended for everyone ages 5 years and older. Currently, the Pfizer-BioNTech COVID-19 vaccine is the only one available to children ages 5 years and older.

COVID-19 vaccines have been used under the most intensive safety monitoring in U.S. history. Scientists have conducted clinical trials with thousands of children, and the results show that COVID-19 vaccines are safe and effective.

Your child cannot get COVID-19 from any COVID-19 vaccine, and there is no evidence that COVID-19 vaccines cause fertility problems.

Your child may have some side effects, which are similar to those seen with other routine vaccines and are a normal sign that their body is building protection. These side effects may affect their ability to do daily activities, but they should go away in a few days. Some people have no side effects and severe allergic reactions are very rare.

Related pages:

• COVID-19 Vaccines for Children and Teens
• Pfizer-BioNTech
• Possible Side Effects
• Families and Children

An employer may require that their workers be vaccinated. Check with your employer to see if they have any rules that apply to you.

Ask your employer if they are making vaccines available to employees and if they are offering time off to get your vaccine. If you are a contractor or work off site, discuss additional vaccination options with your employer.

Learn more about how to find a COVID-19 vaccine so you can get it as soon as you can.

Everyone ages 12 years and older should get a booster shot after they have completed their COVID-19 vaccine primary series. People ages 12 to 17 years old can only get the Pfizer-BioNTech COVID-19 booster shot. People ages 18 years and older should get a booster dose, and either Pfizer-BioNTech or Moderna (mRNA COVID-19 vaccines) are preferred.

Currently, a booster shot is not recommended for children younger than 12 years old.

The number of vaccine doses you need to complete your primary series depends on which vaccine you receive.

• Two doses of Pfizer-BioNTech vaccine should be given 3 weeks (21 days) apart.
• Two doses of Moderna vaccine should be given 4 weeks (28 days) apart.
• Only one dose of Johnson & Johnson’s Janssen (J&J/Janssen) vaccine should be given.

If you receive a vaccine that requires two doses, you should get your second shot as close to the recommended interval as possible. You should not get the second dose earlier than the recommended interval.

COVID-19 vaccines are not interchangeable for your COVID-19 vaccine primary series. If you received a Pfizer-BioNTech or Moderna COVID-19 vaccine for your first shot, you should get the same product for your second shot. If the mRNA vaccine product given for the first dose is not available or is unknown, either mRNA COVID-19 vaccine product may be administered.

People who are moderately or severely immunocompromised may need an additional shot to complete their primary series. See the specific recommendations for people who are moderately or severely immunocompromised.

You should get your second shot as close to the recommended 3-week or 4-week interval as possible. However, if you receive your second shot of COVID-19 vaccine at any time after the recommended date, you do not have to restart the vaccine series. This guidance might be updated as more information becomes available.

Learn more about COVID-19 vaccines that require 2 shots.

Scientists are continuing to monitor how long COVID-19 vaccine protection lasts. Recent studies show that protection against the virus may decrease over time. This reduction in protection has led CDC to recommend that everyone ages 12 years and older get a booster shot after completing their primary vaccination series.

People who received the Pfizer-BioNTech or Moderna COVID-19 vaccine for their primary series should get a booster shot at least 5 months after completing the primary series. People who received Johnson & Johnson’s Janssen COVID-19 vaccine should get a booster shot at least 2 months after getting their first shot.

At this time, CDC recommends getting only one COVID-19 booster shot. CDC continues to review evidence and will update guidance as more information is available.

Learn more about COVID-19 vaccine booster shots.

Related page:

• Vaccines Work

You can get a COVID-19 vaccine and other vaccines, including a flu vaccine, at the same visit. Experience with other vaccines has shown that the way our bodies develop protection, known as an immune response, and possible side effects after getting vaccinated are generally the same when given alone or with other vaccines. Learn more about the timing of other vaccines.

You should get a COVID-19 vaccine even if you already had COVID-19.

Getting sick with COVID-19 offers some protection from future illness with COVID-19, sometimes called “natural immunity.” The level of protection people get from having COVID-19 may vary depending on how mild or severe their illness was, the time since their infection, and their age. No currently available test can reliably determine if a person is protected from infection.

All COVID-19 vaccines currently available in the United States are effective at preventing COVID-19. Getting a COVID-19 vaccine gives most people a high level of protection against COVID-19 even in people who have already been sick with COVID-19.

Emerging evidence shows that getting a COVID-19 vaccine after you recover from COVID-19 infection provides added protection to your immune system. One study showed that, for people who already had COVID-19, those who do not get vaccinated after their recovery are more than 2 times as likely to get COVID-19 again than those who get fully vaccinated after their recovery.

People who were treated for COVID-19 with monoclonal antibodies or convalescent plasma or people who have a history of multisystem inflammatory syndrome in adults or children (MIS-A or MIS-C) may need to wait a while after recovering before they can get vaccinated. Talk to your doctor if you are unsure what treatments you received or if you have more questions about getting a COVID-19 vaccine.

Related pages:

• Benefits of Getting a COVID-19 Vaccine | CDC
• Preparing for Your COVID-19 Vaccination | CDC

No. People with COVID-19 who have symptoms should wait to be vaccinated until they have recovered from their illness and have met the criteria for discontinuing isolation; those without symptoms should also wait until they meet the criteria before getting vaccinated. This guidance also applies to people who get COVID-19 before getting their second dose of vaccine.

People who have had a known COVID-19 exposure should not seek vaccination until their quarantine period has ended to avoid potentially exposing healthcare personnel and others during the vaccination visit. This recommendation also applies to people with a known COVID-19 exposure who have received their first dose of an mRNA vaccine but not their second.

Related pages:

• When to Quarantine
• Ending Home Isolation

Currently, the Pfizer-BioNTech COVID-19 vaccine is the only COVID-19 vaccine available to children ages 5 through 17 years old. For adults ages 18 years and older, the mRNA COVID-19 vaccines (Pfizer-BioNTech or Moderna) are preferred over Johnson & Johnson’s Janssen (J&J/Janssen) COVID-19 vaccine. All COVID-19 vaccines currently authorized and recommended for use in the U.S. are safe and effective. However, mRNA COVID-19 vaccines are preferred based on an updated risk-benefit analysis.

People should be aware that a risk of a rare condition called thrombosis with thrombocytopenia syndrome (TTS) has been reported following vaccination with the J&J/Janssen COVID-19 vaccine. TTS is a rare but serious condition that involves blood clots in large blood vessels and low platelets (blood cells that help form clots). In some instances, TTS following vaccination has been fatal. Cases of TTS have been reported in both men and women and in a wide age range of people 18 years and older. While all ages and sexes are at risk for TTS, women ages 30-49 have the highest risk with about 1 case occurring per 100,000 doses administered. This risk has not been seen in recipients of Pfizer-BioNTech or Moderna COVID-19 vaccines.

Receiving any COVID-19 vaccine is better than being unvaccinated. Widespread vaccination is a critical tool to help stop the pandemic.

Learn more about your COVID-19 vaccination, including how to find a vaccination location, what to expect at your appointment, and more.

Related page:

• Your Vaccination
• Safety of COVID-19 Vaccines
• Ensuring COVID-19 Vaccines Work

If you need a new vaccination card, contact the vaccination provider site where you received your vaccine. Your provider should give you a new card with up-to-date information about the vaccinations you have received.

If the location where you received your COVID-19 vaccine is no longer operating, contact your state or local health department’s immunization information system (IIS) for assistance. Your state’s IIS cannot issue you a vaccination card, but they can provide a digital or paper copy of your vaccination record.

Getting a QR Code or Digital Copy of Your COVID-19 Vaccination Card

• Some vaccination providers and health departments may offer you access to a QR code or digital copy of your COVID-19 vaccination card in addition to giving you a physical CDC COVID-19 Vaccination card.

CDC does not maintain vaccination records or determine how vaccination records are used, and CDC does not provide the CDC, white COVID-19 vaccination record card to people. These cards are distributed to vaccination providers by state and local health departments. Please contact your state or local health department if you have additional questions about vaccination cards or vaccination records.

Related page:

• Getting Your CDC COVID-19 Vaccination Record and Vaccination Card

If you are up to date on your COVID-19 vaccinations, in general, you do not need to wear a mask in outdoor settings.

However, if you are in an area with high numbers of COVID-19 cases,

• consider wearing a mask in crowded outdoor settings and when you are in close contact with others who are not up to date on their vaccinations, and
• wear a mask indoors in public.

If you have a condition or are taking medications that weaken your immune system, you may not be fully protected even if you are up to date on your vaccinations. You should continue to take all precautions for unvaccinated people, including wearing a well-fitted mask, until advised otherwise by your healthcare provider. Learn more about COVID-19 vaccinations for people who are moderately or severely immunocompromised.

CDC does not keep vaccination records or determine how vaccination records are used. To update your records with vaccines you received while outside of the United States, you may:

• Contact the immunization information system (IIS) in your state. You can find state IIS information on the CDC website.
• Contact your healthcare provider or your local or state immunization program through your state’s health department.

The CDC-labeled white COVID-19 Vaccination Record Cards are only issued to people vaccinated in the United States. CDC recommends you keep your documentation of being vaccinated in the other country as proof of vaccination. CDC also recommends checking with your primary care provider or state health department for options to document your vaccination status domestically.

Learn more about COVID-19 vaccination records and vaccination cards.

You are considered fully vaccinated if you

• Received any single-dose COVID-19 vaccine series that is authorized or approved by the U.S. Food and Drug Administration (FDA) or listed for emergency use by World Health Organization (WHO).
• *Received any combinationexternal icon of two doses of an FDA approved/authorized or WHO emergency use listed COVID-19 two-dose series.

*CDC does not recommend mixing different COVID-19 vaccines for the primary series, but CDC is aware that this is increasingly common in many countries outside of the United States. Therefore, for the interpretation of vaccination records, these people are considered fully vaccinated.

Accepted COVID-19 Vaccines

If you received a COVID-19 vaccine that is not authorized or approved by FDA or listed for emergency use by WHO, you may start over with an FDA-authorized or approved COVID-19 vaccine. Please note that no data are available on the safety or effectiveness of COVID-19 vaccination after receiving a non-FDA-authorized or approved COVID-19 vaccine. Wait at least 28 days after you received the last dose of the non-FDA-authorized or approved vaccine before receiving an FDA-authorized or approved COVID-19 vaccine. Visit the clinical considerations webpage for more information.

As with vaccines for other diseases, people who are up to date on their COVID-19 vaccines are optimally protected. Learn more about staying up to date on your COVID-19 vaccines.

People who have been fully vaccinated outside the United States with a COVID-19 vaccine that is FDA-approved or FDA-authorized are eligible to receive an additional primary dose and/or a booster dose, according to the same guidance for people who received these vaccines in the United States.

People who have been fully vaccinated with a COVID-19 vaccine that is not FDA-approved or FDA-authorized but is listed for emergency use by the World Health Organization (WHO) and people who completed a mixed vaccine series composed of any combination of FDA-approved, FDA-authorized, or WHO Emergency Use Listed COVID-19 vaccinesexternal icon are also eligible to receive an additional primary dose (for people with weakened immune systems) and/or a booster dose.

Additional primary dose for those who are moderately or severely immunocompromised

A number of people who are moderately or severely immunocompromised and who were vaccinated abroad should receive an additional primary dose if they meet the following conditions:

• Moderately or severely immunocompromised who are ages 12 and older and have been fully vaccinated should receive an additional primary dose of Pfizer-BioNTech COVID-19 vaccine at least 28 days after receiving the second vaccine dose of their vaccine primary series. Fully vaccinated includes completing a vaccine primary series for:
  • not FDA-Authorized or FDA-approvedpdf icon vaccine but is listed for emergency use by WHO and people who completed a mix and match series composed of any combination of FDA-approved,
  • FDA-authorized vaccine, or
  • WHO Emergency Use Listed COVID-19 vaccines.

Single-dose booster shots

Booster shots should be obtained by people who meet the following conditions. Those who have been fully vaccinated with a COVID-19 vaccine that is not FDA-authorized or FDA-approved but is listed for emergency use by WHO and people who completed a mix and match series composed of any combination of FDA-approved, FDA-authorized, or WHO Emergency Use Listed COVID-19 vaccines. Of these people, those who also are:

• 16 years and older receive a single booster dose of Pfizer-BioNTech COVID-19 vaccine at least 6 months after completing their primary series.
• This also includes people ages 16 years and older who are moderately or severely immunocompromised. These people should receive a single Pfizer-BioNTech COVID-19 booster shot  at least 6 months after completing their additional primary dose.

Visit the clinical considerations webpage for more information.