Frequently Asked Questions About COVID-19 Vaccines

The 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

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: Effective May 12, 2021, CDC has approved the use of the Pfizer-BioNTech COVID-19 vaccine in individuals age 12-15 years in the US population under Food and Drug Administration (FDA) Emergency Use Authorization. 

COVID-19 Vaccines Cannot Cause Disease


About the Vaccines

Which COVID-19 vaccines are available in the US?

Three vaccines have received authorization from FDA for emergency use in the US for the prevention of COVID-19. The Pfizer vaccine is recommended for use in individuals age 12 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. Learn more from CDC.

Back to Top

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.

Back to Top

Who should be vaccinated against COVID-19?

In the US, COVID-19 vaccination is recommended for everyone age 12 years and older.  Contact your local health department for more information about COVID-19 vaccines available in your local area.

Back to Top

When will vaccines be available for children?

Because children were not included in the initial clinical trials, the vaccines are not currently recommended for children younger than 12 years of age. Clinical trials in younger children are underway, and presuming the trials are successful, vaccine recommendations for younger children will be made once the trials are completed.

Back to Top

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.

Back to Top

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 B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.427 (Epsilon), B.1.429 (Epsilon), and B.1.617.2 (the Delta variant).

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, which may lead to more cases of COVID-19, but at this time, 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

Back to Top

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.

Back to Top

Vaccine Safety

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.

Back to Top

Should I be concerned about Guillain Barré syndrome (GBS) after COVID-19 vaccination?

There have been rare reports of Guillain Barré syndrome (a neurological disorder in which the immune system damages nerve cells, causing muscle weakness and sometimes paralysis) in some individuals who have received the J&J/Janssen COVID-19 vaccine. In most cases, symptoms began within 6 weeks of being vaccinated. According to FDA, the chance of occurrence is very low. If you have any of the following symptoms after receiving the  J&J/Janssen vaccine, seek medical care:

  • Weakness or tingling sensations, especially in the legs or arms, that is worsening and spreading to other parts of the body
  • Difficulty walking
  • Difficulty with facial movements, including speaking, chewing, or swallowing
  • Double vision or inability to move eyes
  • Difficulty with bladder control or bowel function

CDC and FDA are actively monitoring these reports and continue to recommend COVID-19 vaccination, as the benefits outweigh the risks.

Back to Top

Should I be worried about myocarditis or pericarditis following COVID-19 vaccination?

There have been rare reports of inflammation of the heart (myocarditis or pericarditis) following vaccination with the mRNA COVID-19 vaccines (Pfizer-BioNtech and Moderna) in the US. Most of the reported cases have been among male adolescents and young adults and have occurred within several days following the second dose of the vaccine. Most patients with myocarditis and pericarditis who received care responded well to medicine and rest and quickly recovered.

If you have any of these symptoms within a week after COVID-19 vaccination, seek medical care:

• Chest pain
• Shortness of breath
• Feelings of having a fast-beating, fluttering, or pounding heart

CDC is actively monitoring these reports and continues to recommend COVID-19 vaccination for everyone age 12 years and older. The known and potential benefits of COVID-19 vaccination outweigh the known and potential risks.

Back to Top

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.

Back to Top

Are COVID-19 vaccines safe for people with liver disease, heart disease, or other chronic health conditions?

COVID-19 vaccines are safe and effective. Multiple studies show that older adults and those with certain medical conditions—like cancer, chronic kidney disease, chronic lung disease, dementia, diabetes (type 1 or type 2), down syndrome, heart disease, HIV, liver disease, and sickle cell disease—are at higher risk of severe illness or death from COVID-19.

Back to Top

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.

Back to Top

Why was use of the J&J/Janssen one-dose vaccine temporarily paused?

The Centers for Disease Control and Prevention (CDC) and US Food and Drug Administration (FDA) temporarily recommended a pause in the use of the J&J/Janssen COVID-19 vaccine to allow experts time to better understand the small number of reported cases of women developing a rare clotting disorder after receiving the vaccine. All reported cases were in women age 18-48 years, and symptoms occurred 6-13 days after vaccination. More than 7.5 million doses of the vaccine had been administered in the US at the time of the pause.

The pause was lifted on April 23, 2021, after scientists reviewed the data and concluded that the benefits of the vaccine far outweigh the risks. Women younger than 50 years old should be aware of the rare risk of blood clots with low platelets after vaccination, and that other COVID-19 vaccines are available where this risk has not been seen. 

Back to Top

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.

Back to Top

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.

Back to Top

Getting Vaccinated

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

If you are fully vaccinated, you can do many things that you did before the pandemic, like getting together with other fully vaccinated people without wearing masks. Even if you are fully vaccinated, the Centers for Disease Control and Prevention (CDC) still recommends wearing a mask in certain places, including public transportation, and you still need to follow guidance at local businesses and workplaces.

Anyone who is not fully vaccinated still needs to wear a face mask, practice social distancing, and take other precautions. Face masks can help prevent an infected individual from spreading the virus. Face masks are not recommended for children less than two years of age or for individuals who have trouble breathing or who cannot easily remove them.

The virus that causes COVID-19 is still circulating, and people are still getting sick and dying. Precautions such as wearing masks in public places, staying at least 6 feet apart from others, and avoiding crowds and poorly ventilated spaces are necessary until enough people are vaccinated.

Back to Top

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.

Back to Top

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.

Back to Top

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.

Back to Top

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.

Back to Top

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.

Back to Top

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.

Back to Top

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.

Back to Top

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.

Back to Top

Who should not receive COVID-19 vaccines?

Authorized COVID-19 vaccines are safe for most people:

  • Current vaccines are not authorized for children less than 12 years of age
  • 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.
  • 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

Women younger than age 50 years should be aware of the rare risk of blood clots with low platelets after vaccination with the J&J/Janssen COVID-19 vaccine. Other COVID-19 vaccines are available where this risk has not been seen.

Back to Top

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.
Back to Top

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.

Back to Top

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.

Back to Top

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.

Back to Top

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.

Back to Top

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.

Back to Top

Updated July 2021

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

Learn more about coronaviruses at