Frequently Asked Questions About COVID-19 Vaccines

COVID-19 Vaccines Cannot Cause DiseaseThe following information addresses frequently asked questions about COVID-19 vaccines. Although there are differences between the vaccines authorized for use in the US, all currently approved vaccines have the following in common:

  • All are nearly 100 percent effective in preventing hospitalization and death
  • All are not currently approved for use in children, but studies are ongoing
  • None contain the live virus or any component of the virus that causes COVID-19
  • Vaccinated people may still be able to transmit the virus to others, which is why it is important to continue wearing a mask and practicing social distancing, even after you have been vaccinated

Information about COVID-19 vaccines is changing rapidly. View the latest information on COVID-19 vaccination from the Centers for Disease Control and Prevention (CDC).

Note: To date, approximately 7 million doses of the Johnson & Johnson (J&J)/Janssen COVID-19 vaccine have been administered in the US, and a small number of cases of a rare and severe type of blood clot have been reported among some recipients. Read more about the current pause in the use of the J&J/Janssen COVID-19 vaccine.

About the Vaccines

Which COVID-19 vaccines are available in the US?

Three vaccines have received authorization from the Food and Drug Administration for emergency use in the US for the prevention of COVID-19. The Pfizer vaccine is recommended for use in individuals age 16 years and older. The Moderna and J&J/Janssen vaccines are recommended for individuals age 18 years and older.

Individuals may receive any age-appropriate COVID-19 vaccine and are encouraged to receive the earliest vaccine available to them.

Because the supply of COVID-19 vaccines is limited in the US, CDC has developed recommendations about who should be vaccinated first.

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What is an mRNA vaccine? Do mRNA vaccines affect DNA?

The vaccines from Pfizer and Moderna are messenger RNA (mRNA) vaccines. mRNA is found in all living cells, and mRNA vaccines work by teaching cells how to make a protein or a piece of a protein that triggers an immune response inside the body. That immune response, which produces antibodies, is what protects against infection if you are exposed to the virus.

mRNA is not the same as DNA, and it cannot combine with our DNA to change our genetic code. It is also relatively fragile, and will only hang around inside a cell for about 72 hours, before being degraded. mRNA vaccines do not affect or interact with DNA in any way. mRNA never enters the nucleus of the cell, which is where DNA (genetic material) is stored.

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When will COVID-19 vaccines be available for the general public?

Because the supply of COVID-19 vaccines is limited in the US, CDC has developed recommendations about who should be vaccinated first. Contact your local health department for more information about COVID-19 vaccination in your area.

This process will take months. It is important to continue wearing masks, social distancing, avoiding crowds, washing hands, and taking recommended steps to help stop the spread of the virus.

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When will vaccines be available for children?

Because children were not included in the first set of clinical trials, the vaccines are not currently recommended for children under the age of 16 years. Clinical trials in younger children are underway, and presuming the trials are successful, vaccine recommendations for children will be made once the trials are completed.

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How long are the vaccines effective? Will I need to be revaccinated each year?

Scientists do not yet know how long the protection from the COVID-19 vaccines will last. These are new vaccines for a new disease, which means there are not yet long-term data. Vaccine researchers and public health experts are closely monitoring vaccine effectiveness and safety, and new information will be shared by the Centers for Disease Control and Prevention (CDC) as it becomes available.

Some vaccines provide life-long protection, such as the measles vaccine. Others require booster doses. For influenza (flu), everyone age 6 months and older should get vaccinated each year.

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Will COVID-19 vaccines work against new mutations of COVID-19?

Viruses constantly mutate, and public health experts expect new variants of a virus to occur. Multiple variants of SARS-CoV-2 (the virus that causes COVID-19) have been documented in the US and globally, including B117, which first emerged in the United Kingdom, and 501Y.V2, which emerged in South Africa.

Scientists are monitoring changes in the virus, and information about these variants is rapidly emerging. The new variants seem to spread more easily and quickly, but at this time, there is no evidence that the variants cause more severe illness or increased risk of death, or make COVID-19 vaccines less effective. Existing vaccines are expected to be effective against the variants and others that may emerge in the short term.

View current CDC information about emerging SARS-CoV-2 variants

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What other vaccines are being developed?

Globally, there are additional vaccine candidates in various stages of testing to evaluate their safety and effectiveness, including some that are based on proven technologies and some that use innovative approaches.

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Vaccine Safety

Why is use of the J&J/Janssen one-dose vaccine currently being paused?

The Centers for Disease Control and Prevention (CDC) and Food and Drug Administration (FDA) are recommending a pause in the use of the J&J/Janssen COVID-19 vaccine to allow researchers at both agencies time to better understand a small number of reported cases of women developing a rare clotting disorder after receiving the vaccine.  As of April 14, 2021, approximately 7 million doses of the vaccine have been administered in the US and six cases of blood clots have been reported. All reported cases were in women age 18-48 years, and symptoms occurred 6-13 days after vaccination.

The pause gives scientists time to review the data and decide if recommendations on who should get the vaccine need to change. CDC and FDA will share more information as soon as possible with healthcare professionals, people who received the vaccine, and the general public.

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If I have already been vaccinated with the J&J/Janssen vaccine, what should I do?

If you received the J&J/Janssen COVID-19 vaccine within the past 3 weeks and develop any of the following symptoms, you should contact a healthcare professional and seek medical treatment right away:

  • severe headache
  • blurred vision
  • fainting
  • seizures
  • abdominal pain (pain in your chest or stomach)
  • leg pain or swelling
  • shortness of breath

Mild fever, mild headache, fatigue, and joint or muscle pain after vaccination are routine and typically go away within 2-3 days.

If you received your vaccine more than three weeks ago, or if you received the Pfizer or Moderna vaccine, your risk is very low and you do not need to take any specific action.

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Has this issue been seen with the other COVID-19 vaccines?

No. As of April 13, 2021, no cases of this blood clot issue have been reported among the more than 180 million people who received the Pfizer-BioNTech or Moderna vaccines. COVID-19 vaccines have undergone and will continue to undergo the most intensive safety monitoring in US history. The pause in the use of the J&J/Janssen vaccine indicates that the US vaccine safety monitoring system is working.

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Are the vaccines safe?

All vaccines used in the US are required to go through extensive safety testing before they are licensed by the US Food and Drug Administration (FDA) or recommended for widespread use.

The new COVID-19 vaccines have been studied in multiple clinical trials, each of which has included thousands of individuals who were followed for a minimum of two months. Decades of experience with other vaccines indicate that the vast majority of adverse reactions occur within the first two months of vaccination.

Vaccinated individuals may have a sore arm, fatigue, headache, and even low-grade fever that lasts one or two days. This is to be expected, and it indicates that the vaccine is working.

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Are COVID-19 vaccines safe for people with allergies?

Individuals who have had severe allergic reactions to other vaccines or injectable therapies should not get vaccinated against COVID-19. People who have other allergies (e.g., allergies to food, animals, venom, environmental, or latex) may be vaccinated but should remain at the vaccination site for 15-30 minutes for observation. Individuals who carry epinephrine (EpiPen©) should bring it with them as a precaution.

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Is it safe to get a COVID-19 vaccine while pregnant or breastfeeding? Do COVID-19 vaccines affect fertility?

Pregnant individuals who are eligible to receive a COVID-19 vaccine may choose to be vaccinated. Breastfeeding is rarely a safety concern with vaccines. There is no evidence that COVID-19 vaccines can reduce fertility. Talk with a healthcare professional if you have questions about getting vaccinated.

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How long after receiving a COVID-19 vaccine can I take an antibiotic safely?

There is no influence or interaction between antibiotics and COVID-19 vaccines, so when indicated, antibiotics may be taken at any time relative to COVID-19 vaccine administration.

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Is it possible to get COVID-19 after receiving the vaccine?

None of the new vaccines contain the live virus that causes COVID-19, so it is not possible to get the disease from the vaccine.

It typically takes a few weeks for the body to build immunity after vaccination. That means it is possible for an individual to be infected with the virus that causes COVID-19 just before or just after vaccination, as the vaccine has not had enough time to provide protection.

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Getting Vaccinated

Can I get a COVID-19 vaccine at the same time as another vaccine?

The Centers for Disease Control and Prevention (CDC) recommends waiting at least 14 days between getting a COVID-19 vaccine and getting any other vaccine, including a shingles vaccine or influenza (flu) vaccine.

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If I already had COVID-19, do I still need to get vaccinated?

CDC recommends COVID-19 vaccination regardless of whether or not an individual was previously infected.

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Should I delay my COVID-19 vaccine if I am scheduled for surgery?

There is no need to delay getting vaccinated against COVID-19 until after surgery. Fever is a potential side effect of COVID-19 vaccines, and having a fever after surgery raises concerns about a possible surgical wound infection. For that reason, it is a good idea to allow at least one week between getting vaccinated and having surgery.

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What side effects should people expect from the vaccines?

Some individuals who are vaccinated may have a sore arm, fever, or other symptoms. These symptoms are normal and are a sign that the body is building immunity.

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What can be done to relieve side effects of COVID-19 vaccines?

Side effects are normal signs that the body is building immunity. These side effects usually go away in a few days. Over-the-counter medicines, such as aspirin, antihistamines, or acetaminophen, may help relieve fever, pain, or discomfort after getting vaccinated—but should not be used before getting vaccinated.

To reduce pain and discomfort in the arm, apply a clean, cool, wet washcloth over the area, and use/exercise your arm gently. To reduce discomfort from fever, drink plenty of fluids and dress in layers that can be removed.

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What is the purpose of my COVID-19 vaccination card, and what should I do if I lose it?

The COVID-19 vaccination card is simply a medical record to help keep track of which type of vaccine you received, when you received it, and when you are due for another dose if necessary. You should keep your vaccination record in a safe place, as with all medical records. It is a good idea to make a copy of the vaccination card and keep the copy secure as well. Avoid carrying the card in your wallet to prevent losing it. Laminating the card is not necessary, and can make it difficult to add booster doses if needed. If you lose your card, contact the site where you received your vaccine or your local health department for a replacement.

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Will I be required to show proof of vaccination to return to work or school?

Vaccine mandates cannot be imposed federally, but some employers or schools may require proof of vaccination.

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After I have been fully vaccinated, why do I still need to wear a mask and take other precautions?

Individuals who have been fully vaccinated against COVID-19 still need to take precautions in public places such as wearing a mask, staying 6 feet apart from others, and avoiding crowds and poorly ventilated spaces. These precautions are necessary until enough people are vaccinated and until scientists learn more, including how well COVID-19 vaccines prevent the spread of the disease.

According to CDC, individuals who have been fully vaccinated can:

  • Gather indoors with other fully vaccinated people without wearing masks
  • Gather indoors with unvaccinated people from one other household (for example, visiting with relatives who all live together) without masks, unless any of those people or anyone they live with has an increased risk for severe illness from COVID-19
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What steps should those who have been fully vaccinated take if they are exposed to someone with COVID-19?

Fully vaccinated individuals who have been around someone who has COVID-19 do not need to quarantine or get tested unless they develop symptoms. However, vaccinated individuals who live in a group setting (like a college dorm or detention facility) and are exposed to someone with COVID-19 should still stay away from others for 14 days and get tested, even if they do not have symptoms.

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Should I get an antibody test after I am fully vaccinated?

No, not at the present time, as commercially available tests do not reliably measure antibodies against spike protein but rather against other parts of the virus. Testing is useful in measuring prior COVID-19 infection only.

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Who should not receive COVID-19 vaccines?

Authorized COVID-19 vaccines are safe for most people:

  • Current vaccines are not authorized for children under the age of 16 years
  • There are no known safety issues for pregnant or breastfeeding women
  • COVID-19 vaccination is recommended for those who have previously tested positive for COVID-19
  • Individuals who have had severe allergic reactions to other vaccines or injectable therapies should not get vaccinated against COVID-19. Those with other allergies may be vaccinated but should remain at the vaccination site for 15-30 minutes for observation, following vaccination.
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When can we expect to return to normal?

Recommended public health measures (including social distancing, face masks, and handwashing) will still be necessary to help slow or stop the spread of COVID-19:

  • While the vaccines appear to be highly effective at preventing disease, they may not prevent asymptomatic infection, meaning that those who have been vaccinated might still be able to get infected without experiencing any symptoms, and, therefore, unknowingly spread the virus.
  • Scientists estimate that to control COVID-19, about 70-80 percent will need to be immune (~250 million individuals in the US). To rely on infections alone to stop the spread of COVID-19, between 1 million and 5.4 million people would die before 250 million become immune.
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Interaction with Antibiotics and Other Drugs

Do COVID-19 vaccines interfere with other drugs and medications?

COVID-19 vaccines do not interfere with the vast majority of prescription and over-the-counter drugs that can be taken safely and effectively by those receiving COVID-19 vaccines. Talk to a healthcare professional if you have specific questions about your medical care.

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Is it safe to take an antibiotic before or after receiving a COVID-19 vaccine?

COVID-19 vaccines do not influence or interact with antibiotics, so when indicated, antibiotics may be taken at any time relative to COVID-19 vaccine administration.

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Is it safe to take a pain reliever when getting a COVID-19 vaccine?

Do not take a pain reliever or fever-reducing drug before receiving a COVID-19 vaccine because these drugs may impact the immune response to the vaccine. If you experience side effects after getting vaccinated, it is safe to take these drugs as needed to treat pain. Patients routinely taking low-dose aspirin or anti-inflammatory medications may continue to take these medications as instructed.

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Is it safe to get a COVID-19 vaccine while taking medication to control a chronic health condition?

COVID-19 vaccines do not interfere with drugs that are taken to control blood pressure, diabetes, cholesterol, lung disease, or other chronic health conditions. COVID-19 vaccines only affect the immune system, which has no impact on the effectiveness of medications to manage chronic conditions.

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Do any drugs or medicines impact the effectiveness of COVID-19 vaccines?

Prescription drugs that affect the immune system—such as certain cancer chemotherapies or drugs for HIV or autoimmune diseases—may impact the effectiveness of COVID-19 vaccines. Even if they do not prevent disease entirely, COVID-19 vaccines can help prevent hospitalization or death, and prescription drugs used to treat other conditions will continue to work when taken as directed.

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Updated April 2021

Sources: Centers for Disease Control and Prevention, Food and Drug Administration

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