Questions About COVID-19 Vaccination

Wondering what shots are recommended, when, and why? Find answers to those questions and more.

I’ve heard there’s a new COVID-19 shot. Should I get it?

The Centers for Disease Control and Prevention recommends everyone ages 5 years and older get a 2023-24 updated vaccine to protect against potentially serious outcomes of COVID-19 illness, including long-lasting effects of the disease, known as long COVID.

You’re eligible if it’s been at least two months since you received any previous COVID-19 vaccine. But note that children younger than 5 years require multiple doses for maximum protection — check with your child’s health care team.

These latest COVID-19 vaccines are produced by the drug companies Moderna and Pfizer-BioNTech. Another updated COVID-19 booster, made by the biotechnology company Novavax, is awaiting federal authorization and recommendations for use.

At this point in the pandemic, are vaccinations against COVID-19 still helpful?

Yes. The virus that causes COVID-19 continues to cause sickness and death, and vaccination remains effective at preventing severe illness and the spread of the disease.

As of September 2023, more than 3 ½ years after COVID-19 was declared a global health emergency, an average of over 19,000 people in the U.S. were being hospitalized weekly with COVID-19, and several hundred people died each week from the disease.

How can I find a COVID-19 vaccine near me?

Call your local pharmacy or check its website for vaccine availability and online scheduling. You can also use the VaccineFinder tool to search for vaccine providers in your area, text your ZIP code to 438829, or call 1-800-232-0233.

Are the COVID-19 vaccines still free?

During the national COVID-19 public health emergency, the vaccines were paid for by the federal government and provided free of charge to everyone. Now that the emergency has ended, you may have to do a little research up front to get the latest shot for free.

Because it’s considered preventive care, the new COVID-19 vaccines are covered 100% by Medicare, Medicaid and most private insurers. Be sure to use an in-network provider if your plan requires it — you can check with your insurer or the vaccine provider in advance.

If you are uninsured, or if your insurance will require any payment for a COVID-19 shot, you can still get the vaccine for free through the government’s Bridge Access Program. (To find these free vaccinations, go to, search using your ZIP code and which COVID-19 vaccine you want, and on the next screen choose “Bridge Access Program Participant.”) The Bridge Access Program is authorized through 2024.

I was vaccinated against COVID-19 soon after the vaccines became available. Am I still protected?

You’re not as well-protected now as you were then. In the U.S., nearly 70% of people completed an initial course of recommended doses (called the “primary series” of vaccination). But the effectiveness of the vaccines fades over time, meaning booster shots are needed to help maintain protection. Also, the virus that causes COVID-19 has changed, or “mutated,” in form since the pandemic’s early days, creating a need for updated vaccine formulations that target newer forms of the virus.

I’ve already had a COVID-19 booster shot or two. Do I need another shot?

Federal officials recommend that almost everyone get one of the newest vaccinations.

Booster shots have been available beginning in the fall of 2021 — but they have evolved. Those first booster shots were additional doses of the original three vaccine formulations approved in the U.S., produced by Pfizer-BioNTech, Moderna, and Johnson & Johnson Janssen.

In August 2022, U.S. officials approved updated formulations of two vaccinations, from Pfizer and Moderna, for use as booster shots. These were called “bivalent” vaccines because they provided a two-pronged attack on the virus, targeting both the original strain that causes COVID-19 and a couple of major subvariants of the virus that had emerged and were making people sick.

In September 2023 the Food and Drug Administration approved the newest formulation of COVID-19 shots, produced by Moderna and Pfizer for 2023-24. These updated, “monovalent” vaccines target one newer variant of COVID’s Omicron strain called XBB.1.5 and are expected to also increase defenses against other, related variants that are now spreading. The previous bivalent shots are no longer available in the U.S.

Currently, the CDC recommends people ages 5 years and older get one of the newly updated vaccines two months after their last shot (children under 5 require a series of shots that may mix previous and new formulations — recommendations are here).

Which COVID-19 vaccine should I get if I’ve never had one before?

You should get a dose of either the newest Moderna or newest Pfizer vaccine, released in September 2023, according to the CDC. You don’t need both.

The Pfizer and Moderna vaccines are a type known as an mRNA vaccine. (Read more about COVID-19 vaccine types.) For people age 12 or older who are unable to get an updated mRNA vaccine, or choose not to, another type of vaccine, made by the biotech company Novavax, is available. The Novavax product is a protein subunit vaccine, and two doses are recommended if you haven’t been vaccinated for COVID-19 before.

Novavax’s vaccine initially received FDA authorization for use in adults and adolescents in the summer of 2022, and was authorized as a booster in adults in October 2022. An updated Novavax formulation is awaiting federal approval.

How should the new 2023-24 COVID-19 vaccinations be given to children?

According to the FDA, which authorized the newest COVID-19 vaccines, anyone 5 years old and up can have a single dose of Pfizer or Moderna’s 2023-24 formulation at least two months after receiving any previous COVID-19 vaccine.

For children ages 6 months through 4 years who have not received any COVID-19 vaccination, three doses of the updated Pfizer vaccine or two doses of the updated Moderna vaccine are authorized. If they have already been vaccinated they can receive one or two doses of the newest vaccines, depending on previous COVID-19 vaccination (check with your child’s health care team).

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

Yes — vaccination will provide extra protection against another case of COVID-19. Because reinfection is less likely during a short window after having COVID-19, you may consider delaying your vaccine by three months from when symptoms started or when you tested positive. But you should take into account your personal risk and rates of COVID-19 in your community, the CDC says.

Wouldn't I be better protected against COVID-19 if I just got infected naturally, instead of getting vaccinated?

There's no way to predict how COVID-19 would affect you. Severe COVID-19 illness, and even death, have occurred in people of all ages — including healthy people. If you do get infected, vaccination helps protect you against severe illness, hospitalization and death.

Will we continue to need COVID-19 booster shots?

Many experts expect COVID-19 vaccinations to be recommended annually, the way the influenza vaccine is now. By the way, those annual flu shots prevent millions of illnesses and medical visits for flu treatment each year. (In the 2019-2020 flu season, vaccination prevented an estimated 7.5 million illnesses, 3.7 million medical visits, 105,000 hospitalizations and 6,300 deaths from flu.)

Can I get my COVID-19 shot at the same time as I get the flu or other vaccines?

Yes. The CDC says a COVID-19 vaccine and other immunizations, such as a flu shot, can be given together, or without any specific time interval in between. The agency recommends almost everyone 6 months and older be vaccinated against flu annually, ideally in September or October.

Influenza vaccination can help keep you and your family healthy this winter — so you might avoid a medical visit at a time when lots of people are sick and contagious. Flu vaccination is particularly important for children age 2 and under and adults 65 and older. It’s also vital if you have any of a variety of medical conditions including kidney disease, diabetes or heart failure; have a body mass index of 40 or higher; or have had a heart attack or stroke.

Discuss flu vaccination with your health care team if you have allergies to eggs or flu shot ingredients, have had a severe allergic reaction to a previous influenza vaccine, have a history of Guillain-Barré syndrome or are feeling ill.

How do the COVID-19 vaccines work?

The Pfizer and Moderna vaccines are a type called a messenger RNA (mRNA) vaccine. Novavax’s is a protein-based (or protein-subunit) vaccine. All these vaccines teach the body how to fight the virus that causes COVID-19 without you actually having to get the illness. None of the vaccines causes the illness — there is no live virus in any of the vaccines.

Research shows the vaccines can help protect you from getting COVID-19, although fully vaccinated people can get infected. (That’s called a “breakthrough infection.”) But more importantly, vaccination has been shown to greatly reduce the risk of getting seriously ill and being hospitalized if you do get COVID-19. Vaccination may also help protect against long-term COVID-19-related illness.

What does ‘primary series’ of vaccinations mean?

The first round of COVID-19 shots most people received was called the “primary series” of vaccinations. If you’re an adult, in most cases that was two doses of the Pfizer vaccine (three to eight weeks apart), two doses of the Moderna vaccine (four to eight weeks apart) two doses of the Novavax vaccine (three to eight weeks apart), or one dose of the now unavailable vaccine made by Johnson & Johnson/Janssen.

With the introduction of the newest mRNA (Moderna and Pfizer) vaccines for 2023-24, only children ages 6 months to 4 years who are previously unvaccinated are advised to receive more than one shot for their initial vaccination (i.e., a primary series). Everyone 5 years and older, previously vaccinated or unvaccinated, is urged to receive one dose of the 2023-24 vaccines, although people who are moderately or severely immunocompromised may be advised by their health care team to get additional shots.

How do I know if I’m ‘immunocompromised’?

Conditions such as advanced HIV infection and some genetic disorders can compromise, or weaken, the immune system. So can treatments including stem cell transplantation, some anti-cancer medicines, high-dose corticosteroids and immune-suppressing drugs used after organ transplantation.

Your health care team can guide you on whether you have a weakened immune system and should receive additional COVID-19 vaccinations. (The CDC has specific guidance, listed by age group, for vaccination in people with compromised immune systems.) Also, continue other COVID-19 precautions according to your health care team’s advice, including masking, distancing and frequent handwashing, and be sure people close to you are vaccinated whenever possible.

What are the most common side effects of vaccination?

Many people have no side effects from COVID-19 vaccination. Many others experience minor effects for a few days, including:

  • Pain, redness or swelling at the injection site
  • Fatigue
  • Headache or muscle pain
  • Chills or fever
  • Nausea

Very young children may also experience irritability or crying, swollen lymph nodes, sleeplessness and loss of appetite. Side effects are more common after the second shot in a two-shot primary series.

Call your health care team if these effects last more than a few days, are worrisome, or if the redness and swelling in the arm worsens after 24 hours. For minor issues, check out the CDC’s advice here.

You can report side effects to the CDC and FDA via the Vaccine Adverse Event Reporting System. (It will be helpful to consult the vaccine record you were given when you were vaccinated, which notes the date and type of vaccination you received as well as the location).

What if I have vaccine-related allergies?

Alert your health care team if you’ve had a severe allergic reaction to previous COVID-19 vaccines; have an allergy to polyethylene glycol (PEG), an ingredient in the Pfizer and Moderna vaccines; or are allergic to polysorbate, an ingredient of the Novavax vaccine. (Here are full lists of the vaccines’ ingredients.) If you have allergies that aren’t related to vaccines, including food, pet or latex allergies, the CDC recommends you get vaccinated for COVID-19.

Can I catch COVID-19 from the vaccine?

No. None of the vaccines available in the U.S. contains the live virus. But because the vaccines teach the body to recognize and fight the virus that causes COVID-19, you might have side effects like fever, which can occur when the immune system is working hard — building your immunity to the virus.

Also, it’s possible you could already have COVID-19 but not be feeling symptoms before vaccination — or could catch the disease right after your shot, before your immune system can protect you. If you’re sick, be sure to follow COVID-19 precautions, including physical distancing, masking and improved indoor ventilation.

What is ‘emergency use authorization’? How does it differ from FDA ‘approval’?

All the COVID-19 vaccines used in the U.S. initially received an official designation called emergency use authorization from the Food and Drug Administration. During a public health emergency such as the COVID-19 pandemic, the FDA can allow the use of medical products such as the new vaccines that haven’t yet received full agency approval if they are needed to fight serious or life-threatening disease and no acceptable alternatives are available. In evaluating the evidence for an emergency use authorization, the agency must decide that the known and potential benefits outweigh the known and potential risks of the medical product in question.

For full approval, the COVID-19 vaccines had to clear the FDA’s standard, more comprehensive review process for quality, safety and effectiveness, which builds on the extensive data previously submitted for emergency use authorizations.

As of September 2023, the updated COVID-19 vaccine formulations produced by Moderna and Pfizer are fully approved for use as a single dose for people ages 12 and up, and have emergency use authorization for use in children 6 months through 11 years old. (Note that the total number of shots differs for infants, very young children and some people with highly weakened immune systems.) Novavax’s COVID-19 vaccine is available under emergency authorization as a two-dose initial series or a single booster six months later for people 12 and older.

Are there serious side effects from COVID-19 vaccination?

Very rarely, a severe, dangerous allergic reaction called anaphylaxis can occur shortly after your shot. Symptoms of anaphylaxis include a swollen throat, a rash that can itch, wheezing or other trouble breathing, and passing out. If you think you are having such a severe reaction after you leave your vaccination site, call 911 immediately.

Experts have estimated anaphylaxis has occurred in about 5 cases per million doses of Pfizer or Moderna vaccines in the U.S. These reactions most commonly happen within 15 minutes of when the shot was given — that’s why there’s a short waiting period, with health care workers nearby if treatment is needed, after your vaccination.

You could also have a less severe allergic reaction within four hours of your shot, with symptoms such as hives, swelling and wheezing or difficulty breathing. (If any symptoms are concerning, seek medical help right away. And if you have any of these allergic reactions, talk to your health care team about what to do regarding future COVID-19 vaccinations.)

In addition, public health experts are monitoring vaccine safety and side effect data for cases of rare heart-related complications, myocarditis or pericarditis, after receiving the Pfizer or Moderna vaccines. (Myocarditis is inflammation of the heart muscle, while pericarditis is inflammation of the heart’s outer lining.) Research shows the benefits of COVID-19 vaccination outweigh the low risk of myocarditis after receiving the vaccine.

Cases of myocarditis and/or pericarditis have been more common in adolescent boys and young men. A 2021 study shows that most people under age 21 who developed myocarditis thought to be linked to COVID-19 vaccination had mild symptoms that improved quickly.

Should I get vaccinated if I’m pregnant — or planning to be?

Yes — the CDC recommends an updated (2023-24) COVID-19 vaccine for women who are pregnant or are anticipating a pregnancy. Pregnant or recently pregnant women face an elevated risk of death or severe illness from COVID-19, including illness requiring hospitalization, intensive care, or a ventilator or other special equipment to breathe, according to the CDC. Also, risk of pregnancy complications with COVID-19 is higher.

Women who are breastfeeding or might become pregnant also are urged to get vaccinated. There is no evidence that any vaccines, including those protecting against COVID-19, cause fertility problems for women or men, the CDC says.

How should I get ready for my vaccination appointment? What should I expect?

If you have a chance to fill out paperwork online before the visit, you’ll save time at your appointment. Plan for only light activity for a day or so after you receive your vaccine, in case you have any effects from the shot, like soreness or feeling a little ill.

Check with your doctor or vaccine provider about whether any medicines you are taking might be a problem. The CDC advises against taking over-the-counter painkillers such as acetaminophen, aspirin or ibuprofen solely as a measure to prevent vaccine side effects.

Bring your photo ID and your insurance card (if applicable). If this is not your first shot, bring the CDC COVID-19 Vaccination Record Card(s) that you received at previous visits, if you still have it. If your vaccine record card is full, ask for another one, if available (note that the CDC is no longer providing these cards).

The actual shot, given in the upper arm muscle, will only take a few seconds. Afterward, you will be asked to wait 15 to 30 minutes to ensure that a risky but very rare and treatable allergic reaction, called anaphylaxis (see “side effects” question above), does not occur. Health care workers who provide vaccinations are ready to treat anyone who has this reaction.

Should I get a COVID-19 vaccine if I have a history of heart disease or stroke?

Yes. People with cardiovascular risk factors, heart disease, and heart attack and stroke survivors should get vaccinated because they are at much greater risk from the virus than they are from the vaccine, according to leaders of the American Heart Association. The AHA urges people with medical conditions to discuss vaccination with their health care team.

Does vaccination affect other medical procedures I might have? I’ve heard mammograms might be a problem.

As part of the normal immune reaction that occurs after COVID-19 vaccination, lymph node swelling can occur in the underarm near where you received your shot. That swelling may show up on your mammogram and can raise a false alarm.

But experts do not recommend delaying mammography after a COVID-19 shot. If you’ve had a COVID-19 vaccination recently, be sure to tell your mammography technician the date of your vaccination and in which arm you received the shot.

You should also consult with your health care team about the timing of your COVID-19 vaccination if you’ve recently been ill or have a major medical procedure scheduled soon.

What are virus ‘variants’? Can the current COVID-19 vaccines protect against them?

When a virus infects you, it hijacks your cells to make numerous copies of itself that can infect other cells. Errors, or mutations, occur during copying. A variant emerges when a copying error proves beneficial to the virus — for instance, by making it more infectious — and is carried forward. The more a virus circulates in a population, the more opportunity there is for mutations to occur and variants to emerge.

Variants to the virus that causes COVID-19 so far have included Alpha, Delta and the one now of most consequence, Omicron. Subvariants, or lineages, of Omicron are currently dominant in the U.S. The newest COVID-19 vaccines target an Omicron variant called XBB.1.5 and are expected to also increase defenses against related variants that are now circulating.

What does ‘herd immunity’ mean?

Herd immunity refers to the point at which enough people in society have protective antibodies against an illness, either from having been vaccinated or previously infected, that it's hard for the disease to spread from person to person. Herd immunity helps protect people who are unable to be vaccinated, such as newborns or people who are allergic to the vaccine.

Experts in infectious diseases now say that achieving herd immunity against the virus that causes COVID-19 is unlikely. That’s because, among other factors, the virus is continually mutating, creating new variants; it can be spread by people without symptoms (making it harder to track and control); rates of vaccination and use of other precautionary measures in the population are inadequate; and protection against new COVID-19 infection provided by previous infection or vaccination isn’t lasting.

Do I still need my COVID-19 vaccination card?

Those COVID-19 Vaccination Record Cards are a handy log of your vaccination history, so they’re worth keeping. (If your card is full, many vaccination sites will be able to provide another one, while supplies last.) But the CDC is no longer distributing those cards.

It’s a good idea to take a photo or make a photocopy of your updated card as a backup record. If you’ve lost your card and need to know your vaccination history, try contacting your vaccination providers or check with your state health department's immunization information system.

Where can I find out more about the COVID-19 vaccines?

The CDC website includes extensive, up-to-date information about COVID-19 vaccination.

How can I take part in a clinical trial of a COVID-19 vaccine or treatment?

The website of the National Institute of Allergy and Infectious Diseases has information on COVID-19 clinical trials.