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COVID-19 Vaccine FAQ

We have created a list of common questions about the COVID-19 vaccines based on current knowledge and understanding. These questions will continue to evolve with time, so we encourage you to check back frequently for the most up-to-date information.

Common Questions about COVID-19 Vaccines:

  1. Who is currently eligible for the COVID-19 vaccine?

Individuals 12 years and older are currently eligible to receive the two-dose Pfizer COVID-19 vaccine, while those 18 years and older can receive the two-dose Moderna or single-dose Janssen vaccine.

  1. The vaccine was produced very quickly. How do I know it is safe?

The U.S. vaccine safety system ensures that all vaccines are as safe as possible. Today, more than 200 million people in the U.S. have received at least one dose of the vaccine and experienced only minimal side effects, further underscoring the safety of the COVID-19 vaccines. Despite what the vaccine project name may suggest, “Operation Warp Speed” does not mean that manufacturers were able to skip steps or cut corners in the vaccine development process. Instead, after development of the vaccine, manufacturers took a secured risk and overlapped the study, manufacturing and distribution phases. The FDA committed to giving these vaccinations priority (not rushed) review at all phases of the studies, which helped speed up the overall process. Ongoing monitoring of vaccine effectiveness and side effect reports will continue to be evaluated by the FDA and the manufacturers.

  1. If I get the COVID-19 vaccine, should I still wear a mask?

Yes. For several reasons, a mask and other proven methods of preventing COVID-19 (hand hygiene and social distancing) are still important even after receiving the vaccine. It typically takes a few weeks for the body to build immunity after vaccination. That means it is possible that a person could be infected with the virus that causes COVID-19 just before or just after vaccination. This is because the vaccine has not had enough time to provide protection. Also, while the vaccines protect you from becoming ill, it is not yet known if the vaccines prevent you from spreading the virus if infected.

In addition, while COVID-19 vaccines are highly effective, there is a small percentage of people who might not be protected while the virus continues to spread – including those with compromised immune systems due to cancer and cancer treatments and those who are unable to be vaccinated due to severe allergic reactions to vaccine ingredients.

Masks also help protect against new strains of the virus, for which vaccine effectiveness is still unclear. For these reasons, it is important to continue practicing safety measures like wearing masks until vaccines are widely administered and the virus is no longer spreading.

  1. If I have already had COVID-19 and recovered, should I still get the COVID-19 vaccine when it is available?

Yes, at this time the vaccine is recommended even if you previously tested positive for COVID-19. Due to the severe health risks associated with COVID-19 and the fact that re-infection with COVID-19 is possible, individuals who have previously been infected with COVID-19 should proceed with getting the vaccine.

  1. Can you contract COVID-19 by getting the vaccine?

No. The vaccine is NOT a live vaccine, and it is NOT possible to contract COVID-19 from receiving the vaccine. Some people experience side effects from the vaccine, such as headache, muscle pain, or fever – but that does not mean you have COVID-19.  It means your body is working to build the necessary immunity against the virus, which is a good thing. 

  1. What are the possible side effects/adverse events from the COVID-19 vaccine? 

The most common adverse reactions reported have been fatigue, headache, fever/chills and joint pain. This means your body is working to build the necessary immunity against the virus.

You can read more in Pfizer’s FDA Briefing Document, Moderna’s FDA Briefing Document and Johnson & Johnson’s (Janssen) FDA Briefing Document about the side effects reported among the vaccine study participants.

  1. How many doses are required? If multiple, when do I get another dose?

The dose regimen for full vaccination will depend on the type of vaccine you receive. For both the Pfizer and Moderna vaccine, two doses are required. The second dose of the Pfizer vaccine should be administered 21 days after the first dose. The second dose of the Moderna vaccine should be administered 28 days after the first dose. It is very important to note that the second dose must be from the same manufacturer as the first dose. The Johnson & Johnson (Janssen) vaccine requires only one dose.

  1. What should I do if I am unable to get the second dose exactly 21 days (Pfizer) or 28 days (Moderna) after the first dose?

While it is recommended that you receive the second dose as soon as feasible after day 21 or day 28, we understand that it might not be possible to receive it on the desired date. This could be due to multiple reasons. Please keep the following in mind if you cannot receive the second vaccine dose on the desired date:

  1. It is strongly preferred that you receive the second dose from the same manufacturer as the first dose. However:
    1. In exceptional situations in which the Pfizer or Moderna vaccine product given for the first dose cannot be determined or is no longer available, any available mRNA (Pfizer or Moderna) COVID-19 vaccine may be administered at a minimum interval of 28 days between doses to complete the vaccination series.
    2. In situations where the same Pfizer or Moderna vaccine product is temporarily unavailable for an individual’s second dose, it is preferable to delay the second dose (up to 6 weeks) to receive the same product than to receive a mixed series using a different product.
  2. Get the second dose as soon as possible after the desired date has passed, as it is better to get the second dose late than not at all. You will still experience the same efficacy in the long run, although you may not see the full effect of the immunity until a few weeks after the second dose.  

  1. How long after receiving my full dose regimen until it is considered effective?


Similar to the flu vaccine, it typically takes a few weeks for the body to build immunity after vaccination. That means it’s possible a person could be infected with the virus that causes COVID-19 just before or just after vaccination and get sick. This is because the vaccine has not had enough time to provide protection. As a general rule, the vaccine is considered effective about two weeks after your full dose regimen, according to the manufacturers. If you are receiving the Pfizer or Moderna vaccines, which require two doses, there is evidence that the first dose will begin providing some immunity, but it is still very important to receive the second dose for optimal results.

  1. Can I choose which vaccine I get?

    In general, we do not recommend waiting for a specific manufacturer, but your age and health history must be carefully considered before deciding which vaccine is right for you, as some may have increased risks. All FDA-approved or FDA-authorized COVID-19 vaccines have been proven effective in reducing the risk of becoming infected with the SARS-CoV-2 virus that causes COVID-19, decreasing the likelihood of having a severe case of the illness and reducing hospitalizations and deaths due to COVID-19 disease. Early defense is better than no defense against COVID-19. Talk to your doctor to determine the most appropriate vaccine for you.

  1. If receiving a two-dose regimen, should those who experience significant side effects from their first COVID-19 vaccine dose expect significant or worse side effects with the second dose? What about those who were previously COVID-19-positive?

Based on data from the Pfizer and Moderna vaccines, there appears to be an increased incidence of experiencing certain side effects from the second dose of the COVID-19 vaccine compared to the first dose (e.g., fever, fatigue, headache, chills, muscle pain, and joint pain). This does not mean that all vaccine recipients will experience these side effects with the first or second dose. A full list of the reported side effects comparing Dose 1 and Dose 2 may be found within the Pfizer BioNTech EUA and the Moderna EUA .

At this time, we do not have definitive data to state whether vaccine side effects are worse in patients who were previously positive for COVID-19.

  1. How long will I need to be observed after I get the vaccine?

In general, a 30-minute observation period is recommended for anyone with a history of severe allergic reactions (due to any cause), and a 15-minute observation period is recommended for all other individuals.

  1. Will the COVID-19 vaccine result in a false positive COVID-19 test?

No, COVID-19 vaccination will not cause a false positive COVID-19 viral test. Per CDC guidance, the immunity response from a COVID-19 vaccine could possibly result in a positive antibody test, which indicates previous infection and potential protection against the virus.

  1.  If I become COVID-19-positive following my first dose of the vaccine, should I take the second dose?

Per CDC guidance, you may receive the vaccine (either dose) following resolution of symptoms, if any, and completion of the quarantine period.

  1. What ingredients are included in the COVID-19 vaccines?

Ingredients for authorized COVID-19 vaccines can be found via this CDC link. Individuals with allergies to any of the vaccine components should discuss concerns with their healthcare provider before receiving the vaccine.

  1. Can the COVID-19 vaccine be administered to children?

The Pfizer COVID-19 vaccine is recommended for those ages 12 and over.

  1. Is there a COVID-19 vaccine available for children younger than 12 years old?

Currently, 12 years old is the youngest age threshold for receiving the COVID-19 vaccine based on current studies. This age requirement could eventually be adjusted to include younger children as research and clinical trials continue. To date, the Pfizer-BioNTech COVID-19 vaccine is the only vaccine that has been authorized for use in individuals ages 12 and older.

  1. Can the COVID-19 vaccine be administered to pregnant women?

COVID-19 vaccination is recommended for all people aged 12 years and older, including people who are pregnant, lactating, trying to get pregnant now, or might become pregnant in the future. Any of the currently FDA-approved or FDA-authorized COVID-19 vaccines can be administered to people in these groups; ACIP does not state a product preference. However, all women less than 50 years should be aware of the rare risk of TTS after receipt of the Janssen COVID-19 vaccine and the availability of other currently FDA-approved or FDA-authorized COVID-19 vaccines (i.e., mRNA vaccines) for which this risk has not been seen. See also People with a history of thrombosis or risk factors for thrombosis. There is no evidence that any of the COVID-19 vaccines affect current or future fertility.

    19. I’ve read that fertility could be impacted by the COVID-19 vaccine. Is that true?

There has been no demonstrated link between vaccines and infertility in the studies conducted to date. The CDC reports there is no evidence that the COVID-19 vaccines cause fertility problems, and the American College of Obstetricians and Gynecologists states that the vaccine studies do not indicate any safety concerns for those who are pregnant or want to become pregnant.

  1. What does it mean that the Pfizer COVID-19 vaccine has received full approval from the Food and Drug Administration (FDA)?

Receiving full approval means the Pfizer vaccine now carries the FDA's strongest endorsement of safety and effectiveness. This is based on thorough research and comprehensive data review over many, many months. You can read more about the Pfizer vaccine receiving full FDA approval below in the FDA Approval of Pfizer COVID-19 Vaccine FAQ section.

  1. Why is a third dose of the COVID-19 vaccine necessary? Is it not as effective as we thought?

COVID-19 vaccines have been proven safe and highly effective, even against the Delta variant.

FDA Approval of Pfizer COVID-19 Vaccine FAQ

  1. What does it mean that the Pfizer COVID-19 vaccine has received full approval from the Food and Drug Administration (FDA)?

Receiving full approval means the Pfizer vaccine now carries the FDA's strongest endorsement of safety and effectiveness. This is based on thorough research and comprehensive data review over many, many months.

  1. What did the approval process involve?

Full FDA approval only occurs when enough data demonstrate that the vaccines are safe and effective for the majority of people who receive them. After many months of studies and hundreds of millions having received a COVID-19 vaccine, the FDA has substantial information on how safe and effective the COVID-19 vaccines are in protecting people, how well they prevent severe disease, and how the vaccines are safely and consistently manufactured. 

  1. What data did the FDA review?

The Pfizer-BioNTech COVID-19 vaccine underwent the FDA’s standard process for reviewing the quality, safety and effectiveness of medical products. The FDA evaluates data and information included in the manufacturer’s submission of a biologics license application (BLA). The agency also conducts its own analyses of the information in the BLA to make sure the vaccine is safe and effective and meets the FDA’s standards for   approval.The FDA stated the BLA submitted by Pfizer “builds on the extensive data and information previously submitted that supported the EUA, such as pre-clinical and clinical data and        information, as well as details of the manufacturing process, vaccine testing results to ensure vaccine quality, and inspections of the sites where the vaccine is made.”

  1. Is the Pfizer COVID-19 vaccine considered safer than the other two vaccines still under emergency use authorization?

Like the Pfizer vaccine, both of the currently FDA-authorized COVID-19 vaccines (single-dose Johnson & Johnson/Janssen and two-dose Moderna) have been proven safe and effective based on extensive research. Pfizer was the first COVID-19 vaccine manufacturer to complete the arduous application and rigorous inspection process for full approval.

  1. Does FDA approval of the Pfizer vaccine apply to everyone 12 years old and up?

No. At this time, the vaccine has received full FDA approval for individuals who are 16 years and older. The vaccine is still under emergency use authorization (EUA) for those who are 12-15 years old until Pfizer files its application for this specific age group. The vaccine is also still under EUA for the third dose for immunocompromised individuals.

  1.  Is Logan Memorial Hospital planning to require the vaccine for healthcare workers since Pfizer has received full approval?

We are carefully evaluating our next steps in light of the FDA’s decision to grant full approval for the Pfizer COVID-19 vaccine. At this time, we are still strongly encouraging and supporting all of our staff and our community to become fully vaccinated. We are hopeful that the FDA’s decision will help reduce vaccine hesitancy among unvaccinated individuals and encourage them to roll up their sleeves to protect themselves and those around them from COVID-19.
 

  1. When will the other currently available COVID-19 vaccines be approved?

Moderna has applied for full approval, and its vaccine is still being evaluated. Johnson & Johnson has indicated that it will likely apply for full approval later this year.

  1. Will the name of the Pfizer COVID-19 vaccine change with the FDA approval?

Comirnaty will be the brand name of the Pfizer mRNA COVID-19 vaccine. It will likely not be commercially available until 2022. Until more information is available, the   Pfizer vaccine doses will continue to be distributed to states using the existing process.

  1. Once Comirnaty is commercially available, will individuals have to pay for the vaccine? 

Cost and pricing information is not yet available for the FDA-approved product.

COVID-19 Vaccine  3rd Dose for Immunocompromised Individuals

  1. Why is a third dose of the COVID-19 vaccine necessary? Is it not as effective as we thought?

COVID-19 vaccines have been proven safe and highly effective, even against the Delta variant. The CDC’s Advisory Committee on Immunization Practices (ACIP) now recommends an additional dose of the mRNA COVID-19 vaccines (Pfizer and Moderna) specifically for people who are moderately to severely immunocompromised. A third dose will help this vulnerable population enhance their immune response and further protect them from serious – and potentially prolonged – illness.

  1. Why is a third dose only recommended for immunocompromised individuals at this time?

Studies have shown that immunocompromised individuals typically have less of an immune response after initially completing a 2-dose COVID-19 vaccine series than those who are non-immunocompromised. The third dose is intended to help enhance their immune response by increasing antibody levels for greater protection against the virus.

  1. What are the criteria for receiving a third dose?

Individuals may qualify for a third dose if they are moderately or severely immunocompromised due to a medical condition or receipt of immunosuppressive medications or treatments. This includes people who have: 

  • Been receiving active cancer treatment for tumors or cancers of the blood 
  • Received an organ transplant and are taking medicine to suppress the immune system 
  • Received a stem cell transplant within the last 2 years or are taking medicine to suppress the immune system 
  • Moderate or severe primary immunodeficiency (such as DiGeorge syndrome, Wiskott-Aldrich syndrome) 
  • Advanced or untreated HIV infection 
  • Active treatment with high-dose corticosteroids or other drugs that may suppress your immune response 

  1. Is a doctor’s permission or a prescription required?

No. The CDC has indicated that immunocompromised people will not need a doctor’s permission or a prescription to get a third shot. They will only need to attest that they meet the eligibility requirements for an additional dose. Individuals who are unsure whether they meet the criteria above should consult their provider. 

  1. Can immunocompromised individuals who initially received the Johnson & Johnson/Janssen COVID-19 vaccine now receive a dose of the mRNA vaccine?

Currently, there are insufficient data to support the use of an mRNA COVID-19 vaccine dose after a single-dose J&J/Janssen COVID-19 vaccination series in immunocompromised people. The FDA and CDC are actively working to provide guidance to immunocompromised individuals who previously received the single-dose J&J/Janssen vaccine.

  1. What if someone has a chronic medical condition like diabetes or asthma? Can they get the third dose now?

These individuals should not receive a third dose at this time. However, it is expected that the general public will be able to get a booster shot sometime this fall. We anticipate that the booster dose will first be available to healthcare workers, first responders and nursing home residents.

  1. What is the difference between a third dose and a “booster” shot? Are they the same thing?

The vaccine dose is the same, but the intended purpose is different. The third dose is intended to improve immunocompromised people’s response to the initial vaccine series. A booster dose is given to people when the immune response to a primary vaccine series is likely to have waned over time.

  1. How long after completing the 2-dose series should an immunocompromised individual receive a third dose?

The CDC recommends that people with moderately to severely compromised immune systems receive an additional dose of mRNA COVID-19 vaccine at least 28 days after a second dose of the Pfizer or Moderna vaccine.

  1. Where can someone get a third dose?

Check www.vaccines.gov to find a COVID-19 vaccine near you.