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COVID-19 Vaccine Frequently Asked Questions (FAQs)

Updated November 23, 2021

Some of the information below is provided by the Centers for Disease Control and Prevention (CDC), US Food and Drug Administration and the Missouri Department of Health and Senior Services (DHSS).

Why should I get the COVID-19 vaccine?

  • Helping to slow and stop the spread of COVID-19 is a team effort. You play a key part in keeping you and your family healthy.
  • Getting the COVID-19 vaccine adds one more layer of protection for you, your family, friends, coworkers and others.
  • If we use all of the tools we have – getting vaccinated, wearing a mask, practicing social distancing and washing our hands often – the sooner we can “get back to normal.”
  • Vaccines boost your immune system, so it will be ready to fight the virus if you are exposed.

Who is eligible to get the vaccine?

Currently, all people ages 5 and older are eligible to be vaccinated. 

How do I know the vaccine is safe?

All COVID-19 vaccines were tested in clinical trials involving tens of thousands of people to make sure they meet safety standards and protect adults of different ages, races and ethnicities. This was a transparent, rigorous process.

Millions of Americans have received the Pfizer (Comirnaty), Moderna and Johnson & Johnson (Janssen) vaccine, with the vast majority experiencing minor, temporary side effects. Medical and research professionals using public health data have reviewed final COVID-19 vaccine data.

The FDA has given full approval to the Pfizer vaccine for individuals ages 16 and older. The Pfizer vaccine also continues to be available under emergency use authorization (EUA) for the following:

  • For individuals ages 5-15; 
  • For the administration of a third dose in certain immunocompromised individuals (28 days after second dose);
  • For individuals age 65 years and older (six months after second dose);
  • For individuals ages 18 through 64 at high risk of severe COVID-19 (six months after second dose); and 
  • For individuals ages 18 through 64 with frequent institutional or occupational exposure to SARS-CoV-2 (six months after second dose).

The Moderna and Janssen vaccines also have been approved for emergency use.

The Centers for Disease Control and Prevention (CDC) and the US Food and Drug Administration (FDA) will keep monitoring the vaccines to look for safety issues. If an unexpected adverse event is seen in vaccinated individuals, experts quickly study it further to assess whether it is a true safety concern. Experts then decide whether changes are needed in US vaccine recommendations. This monitoring is critical to help ensure that the benefits continue to outweigh the risks for people who receive vaccines.

What is the cost of getting the COVID-19 vaccine?

No person can be billed for the COVID-19 vaccine itself. The vaccines are free from the federal government.

Vaccination providers may charge an administration fee to insurance, Medicaid or Medicare. The administration fee helps cover the cost of vaccination supplies and related expenses.

For those with insurance, this administration fee will be billed to their health plan. Individuals receiving the COVID-19 vaccine will not pay any out-of-pocket costs.

Missourians without health insurance will be able to receive the vaccination at no cost to them.

Should pregnant patients get the COVID-19 vaccine?

COVID-19 vaccination is recommended for all people 5 years and older, including people who are pregnant, breastfeeding, trying to get pregnant now, or might become pregnant in the future.

Evidence about the safety and effectiveness of COVID-19 vaccination during pregnancy has been growing. These data suggest that the benefits of receiving a COVID-19 vaccine outweigh any known or potential risks of vaccination during pregnancy.

There is currently no evidence that any vaccines, including COVID-19 vaccines, cause fertility problems in women or men.

Pregnant and recently pregnant people are more likely to get severely ill with COVID-19 compared to non-pregnant people.

If you are pregnant, you might want to have a conversation with your healthcare provider about COVID-19 vaccination. 

Should cancer patients get the COVID-19 vaccine?

Many expert medical groups recommend that most people with cancer or a history of cancer get the COVID-19 vaccine. This includes people who have already had COVID-19. Cancer patients should discuss the risks and benefits of getting the COVID-19 vaccine with their cancer doctor.

How do mRNA vaccines, such as the Pfizer-BioNTech and Moderna COVID-19 vaccine, work?

The mRNA (messenger RNA) vaccine is a type of vaccine used to protect individuals against infectious disease. These vaccines are new, but they are not unfamiliar. Researchers have been working with them for decades. The mRNA vaccine works by teaching our cells how to make a protein, or part of a protein, and this protein triggers an immune response from our bodies.

The mRNA vaccine essentially teaches our cells how to make a protein by giving our cells a set of instructions, much like a builder uses a blueprint for construction, to create a piece of what is called the spike protein. The spike protein is found on the surface of the virus that causes COVID-19.

Once the vaccine is placed into our arm muscle, the instructions, or the mRNA, are then present inside our muscle cells. The cells then follow the instructions (or blueprint) to make a protein piece. After the protein piece is made, our cell breaks down the instructions and gets rid of it.

Next, our cell displays the created protein piece on its surface. Our immune system recognizes that the protein does not belong there and begins building an immune response by making antibodies. This process is similar to what happens when a person is naturally infected by the COVID-19 virus.

The mRNA vaccine teaches our bodies how to protect us against future infection from COVID-19.

Watch this video on the different COVID-19 vaccines.

Does the mRNA vaccine alter my DNA?

No. The mRNA vaccine does not affect or interact with your DNA in any way. The mRNA vaccine never enters the nucleus of the cell, which is where our DNA is stored. The cell breaks down and gets rid of the mRNA soon after it is finished using the instructions provided by the vaccine.

Information on mRNA vaccines provided by the Centers for Disease Control and Prevention (CDC). Visit to learn more.

Can I get COVID-19 from the vaccine?

No. None of the COVID-19 vaccines currently authorized for use or in development in the United States use the live virus that causes COVID-19. Both the Pfizer and Moderna COVID-19 vaccine are mRNA (messenger RNA) vaccines, which do not use a live virus and cannot give someone COVID-19 or make them contagious to others. The Janssen vaccine also does not contain the SARS-CoV-2 virus and cannot give you COVID-19.

What are the ingredients in the COVID-19 vaccine?

None of the current authorized COVID-19 vaccines contain eggs, gelatin, latex or preservatives. All COVID-19 vaccines are free from metals. Learn more about the ingredients in the following vaccines:

Pfizer-BioNTech vaccine

Moderna vaccine

Janssen vaccine (Johnson & Johnson)

How long does immunity last after vaccination?

How long COVID-19 vaccine protection lasts is unknown. Recent studies show that protection against the virus that caused COVID-19 may decrease over time. This reduction in protection has led the CDC to recommend those ages 18 and older get a booster shot.

What can I expect when I get the COVID-19 vaccine?

Before Vaccination

  • See if a COVID-19 vaccine is recommended for you.
  • Learn about the different types of vaccines offered.

During Vaccination

  • When you go to your appointment, remember to wear a mask and stay at least six feet away from others.
  • You should receive a vaccination card or printout that tells you what COVID-19 vaccine you received, the date you received it, where you received it and when your next dose is due (if you get the Pfizer or Moderna vaccines). The Janssen vaccine is a one-dose shot.
  • With the Pfizer and Moderna COVID-19 vaccines, you will need two doses in order for the vaccine to be maximally effective. The second dose is usually given a few weeks after the first. Be sure to get the second dose on time -- even if you have side effects after the first one, unless a vaccination provider or your doctor tells you otherwise.

After Vaccination

  • Ask your healthcare provider about getting started with v-safe, a free, smartphone-based tool that uses text messaging and web surveys to provide personalized health check-ins after you receive a COVID-19 vaccination. V-safe also reminds you to get your second dose if you get the Pfizer or Moderna vaccines. The Janssen vaccine is a one-dose shot.
  • After any vaccination, it takes time for your body to build protection. COVID-19 vaccines that require two doses will usually not fully protect you until about two weeks after your second dose. You are considered fully vaccinated after two weeks of the one-dose Janssen vaccine.
  • You may have some side effects, which are normal signs that your body is building protection in response to the vaccine. In clinical trials, most people reported that symptoms developed the day of or the first two days after the vaccine and went away by three days after the vaccine. Side effects are more common after the second dose. The most commonly reported side effects included the following:
    • Fever or chills
    • Headache
    • Fatigue/tiredness
    • Muscle pain
    • Nausea
    • Pain and/or swelling at the vaccination site on the arm
  • Consult your healthcare provider if you have any of the following symptoms after getting the vaccine:
    • Swelling or redness at the vaccination site that increases after 24 hours
    • High fever (above 102°F) that cannot be reduced with fever-reducing medicine
    • Shortness of breath or difficulty breathing
    • Rash
    • Your symptoms do not improve in two to three days

Do I still need to wear a mask and practice social distancing after I am fully vaccinated?

In general, people are considered fully vaccinated:

  • Two weeks after their second dose of the Pfizer or Moderna vaccines, or
  • Two weeks after Johnson & Johnson’s one-dose Janssen vaccine.

If you are fully vaccinated, you can resume activities that you did prior to the pandemic. 

To reduce the risk of being infected with the Delta variant and possibly spreading it to others, wear a mask indoors in public if you are in an area of substantial or high transmission. You might choose to wear a mask regardless of the level of transmission if you have a weakened immune system or if, because of your age or an underlying medical condition, you are at increased risk for severe disease, or if a member of your household has a weakened immune system, is at increased risk for severe disease, or is unvaccinated.

If you have had close contact with someone who has COVID-19, you should get tested five to seven days after your exposure, even if you do not have symptoms. You should also wear a mask indoors in public for 14 days following exposure or until your test result is negative. You should isolate for 10 days if your test result is positive.

If you travel in the United States, you do not need to get tested before or after travel or self-quarantine after travel.

Learn more about what you can do when you are fully vaccinated.

Am I still considered fully vaccinated if I do not get a booster shot?

Yes. Everyone is considered fully vaccinated against COVID-19 two weeks after their second dose in a two-shot series, such as the Pfizer-BioNTech or Moderna vaccines, or two weeks after a single-dose Johnson & Johnson (Janssen) vaccine.

Why do I need two doses of the COVID-19 vaccine?

The Pfizer and Moderna COVID-19 vaccines require two doses. The first dose helps the immune system recognize the virus, and the second dose strengthens the immune response. You need both to get the best protection. Be sure to get the second dose on time -- even if you have side effects after the first one, unless a vaccination provider or your doctor tells you otherwise.

Patients who do not receive the second vaccination dose at 21 days (Pfizer) or 28 days (Moderna) should still receive that second dose as soon as possible thereafter.

Do I need a third dose of the COVID-19 vaccine?

For Immunocompromised Individuals:

The US Food and Drug Administration (FDA) has amended the emergency use authorizations (EUAs) for both the Pfizer and Moderna COVID-19 vaccines to allow certain immunocompromised individuals -- specifically, solid organ transplant recipients or those who are diagnosed with conditions that are considered to have an equivalent level of immunocompromised -- to receive a third dose of the Pfizer or Moderna vaccines.

If you are immunocompromised, you may receive a third dose of the Pfizer or Moderna vaccine 28 days after the second dose.

The third dose may still not provide full immunity to COVID-19 in people who are immunocompromised, and you should continue to maintain appropriate precautions to help prevent COVID-19.

People who are immunocompromised have a reduced ability to fight infections and other diseases, and they are especially vulnerable to infections, including COVID-19.

Do I need a booster dose of the COVID-19 vaccine?

The Missouri Department of Health and Senior Services (DHSS) has amended the state’s standing orders for COVID-19 vaccine administration immediately authorizing use of a single booster dose for all individuals ages 18 and older after completion of primary vaccination with any FDA-authorized or approved COVID-19 vaccine. This follows the FDA and CDC’s announcements authorizing and endorsing the use of single dose boosters for all adults.

Those who are 18 or older and fully vaccinated against COVID-19 are eligible for a booster shot:

  • At least two months after a one-dose vaccine of Johnson & Johnson (Janssen), or
  • At least six months after a two-dose vaccine of Pfizer BioNTech or Moderna.

Mix and Match

The FDA also has approved the use of each of the available COVID-19 vaccines as a “mix and match” booster dose in eligible individuals following completion of primary vaccination with a different available COVID-19 vaccine.

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

Yes, you should be vaccinated regardless of whether you already had COVID-19 because research has not yet shown how long you are protected from getting COVID-19 again after you recover from COVID-19. Also, vaccination helps protect you even if you’ve already had COVID-19.

Evidence is emerging that people get better protection by being fully vaccinated compared with having had COVID-19. One study showed that unvaccinated people who already had COVID-19 are more than two times as likely than fully vaccinated people to get COVID-19 again.

If you were treated for COVID-19 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 are still learning more about how long vaccines protect against COVID-19. 

Can I get the COVID-19 vaccine and other vaccines at the same time?

You can get a COVID-19 vaccine and other vaccines, including a flu vaccine, at the same visit. You no longer need to wait 14 days between vaccinations. Experience with other vaccines has shown that the way our bodies develop protection, known as an immune response, after getting vaccinated and possible side effects of vaccines are generally the same when given alone or with other vaccines. Learn more about the timing of other vaccines.

What side effects are reported after getting a COVID-19 booster shot?

The most common side effects after a booster shot are fatigue and pain at the injection site. Overall, most side effects were mild to moderate and similar to side effects after a 2-dose series. Like the two-dose series, serious side effects are rare, but may occur.

Learn more about possible side effects after COVID-19 shots.

Why should I consider vaccination for my child?

Pediatricians, infectious disease doctors and other experts overwhelmingly recommend COVID-19 vaccination in most cases.

With many children back in school and participating in extracurricular activities, COVID-19 vaccination among children as young as age 5 is critical to preventing infection and possible severe disease, as well as reducing the spread of COVID-19. There are approximately 28 million children between the ages of 5 and 11 in the United States, and there have been nearly 2 million cases of COVID-19 within this age group during the pandemic. While fewer children have been sick with COVID-19 compared to adults, children can be infected with the virus, and there is no way to tell in advance if a child will get a severe or mild case. After a natural infection, some children have developed a rare but serious disease that is linked to COVID-19 called multisystem inflammatory syndrome (MIS-C).

As more variants of COVID-19 develop, vaccination continues to be our best tool to reduce the chances that the virus has to mutate.

Choosing vaccination will:

  • Protect your child from severe illness and disease
  • Maintain in-person school, sports and extracurricular activities
  • Protect your family members by reducing transmission
  • Protect our communities from future variant development

What side effects from the COVID-19 vaccine have been observed in children?

Side effects from the COVID-19 vaccines in children and adults are similar. Your child may experience mild side effects like a sore arm, body aches, chills, headache, nausea, tiredness or fever. These are normal signs that their body is building protection, but they should go away in a few days.

How is a child’s vaccine different from the adult vaccine?

The Pfizer vaccine for children ages 5 through 11 has the same active ingredients as the vaccine given to adults and adolescents. However, the vaccine for children comes in a different vial with a different color cap. The Pfizer vaccine that is given to adults and adolescents cannot be used for children ages 5 through 11 years. Children ages 5 through 11 will receive an age-appropriate dose that is one-third of what adolescents and adults receive. Smaller needles, designed specifically for children, are used for children ages 5 through 11 years. COVID-19 vaccine dosage does not vary by patient weight but by age on the day of vaccination. Children are still required to get two doses three weeks apart to be considered fully vaccinated.

What should a parent do if a child turns 12 after they get their first dose of the pediatric vaccine but before the second dose is due?

COVID-19 vaccine dosages are based on age and not size or weight. If a child turns from 11 to 12 years of age in between their first and second dose and receives the pediatric Pfizer COVID-19 vaccine for their first dose, it is recommended by the CDC to administer the second dose using dosing guidance for those 12 and up.

Is Phelps Health offering COVID-19 vaccines for children?

Yes, Phelps Health is offering the Pfizer COVID-19 vaccine for children ages 5 through 11 in the Pediatrics Clinic. Please call (573) 426-3225 to schedule a COVID-19 vaccine for your child(ren). A parent or guardian must sign the consent form at and be present with their teen when the child is vaccinated.

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