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Get the answers to common questions about the COVID-19 vaccines, including vaccine safety, who should get the vaccine and when the vaccine will be available.

COVID-19 Vaccine Prevention and Safety

Will a vaccine prevent COVID-19?

Yes.  The COVID-19 vaccines work by teaching your immune system how to recognize and fight the virus that causes COVID-19.  This helps protect you from getting sick with COVID-19.

How do we know that the COVID-19 vaccines are safe and effective?

The U.S. vaccine safety system ensures that all vaccines are as safe as possible. The two COVID-19 vaccines that are available in the U.S. have been tested in research studies with many thousands of people. These studies have shown that the vaccines are safe and effective.

How long will a vaccine protect people?

It is too soon to know how long a vaccine will last. We do not know yet if people will need to get the vaccine one time, every once in a while, or every year like a flu shot. It is currently being researched. 

COVID-19 Vaccine Development

What is the difference between the Pfizer-BioNTech and Moderna Vaccine?

The Pfizer-BioNTech and Moderna vaccines are similar. Both vaccines use tiny parts called messenger RNA (mRNA) carried in very tiny lipid parts.  The two vaccines differ in the way the mRNA is built or the way the lipids are used.

Both vaccines require two doses. You will receive two doses from the same manufacturer. For the Pfizer vaccine the second dose is 21 days after the first dose. For the Moderna vaccine, the second dose is 28 days after the first dose.

The Pfizer vaccine is approved for people 16 years old and older, and Moderna is approved for 18 and older.

Both vaccines are being given at LG Health and in Lancaster County. The vaccine you get will depend on which one is available. Both vaccines are equally safe and effective.

What ingredients are in the mRNA vaccines?

The mRNA vaccines contain:

  • mRNA – The mRNA is a blueprint that teaches your cells to make one protein from the virus that causes COVID-19 and the antibodies against it.
  • Lipids – These are molecules that are not able to dissolve in water. They protect the mRNA so that it does not break down before it gets into our cells. These lipid particles can be thought of as little “bubbles of fat” that surround the mRNA like a protective wall and make it easier for the mRNA to enter cells.
  • Salts – Salts, similar to table salt, are used to keep the pH of the vaccine close to that found in the body, so the vaccine does not damage cells when it is administered.
  • Sugar – This ingredient is the same as the sugar you put in your coffee or on your cereal. In the vaccine, it helps keep the “bubbles of fat” from sticking to each other or to the sides of the vaccine vial.
  • The mRNA vaccines do NOT contain:

  • Blood products
  • Antibiotics
  • DNA
  • Fetal cells
  • Pork products
  • Egg proteins
  • Preservatives (e.g., Thimerosal)
  • How do mRNA vaccines work?

    The COVID-19 vaccines prevent or lessen illness from the coronavirus. Both the Pfizer-BioNTech and Moderna vaccines have mRNA, which make the virus’ spike protein. This protein lets the virus attach to cells in our body. When we get the vaccine, we develop antibodies to the spike protein. This stops the virus from attaching to cells when exposed to the virus. Other parts of the body that prevent infection are made active by the vaccines to protect against future COVID-19 infection.

    Getting Vaccinated

    Who should get the vaccine?

    The vaccine is recommended for most people over age 16. The Pfizer vaccine is approved for people 16 years and older, and Moderna is approved for 18 and older. The vaccines have only been studied in adults. They have not been studied in children yet.

    These people can get the vaccine, but they should talk to their doctor first:

    • People with a history of severe allergy to any vaccine or injectable medication
    • People who are pregnant or breastfeeding
    • People with immune-compromising or autoimmune conditions
    • People on blood thinners.

    If you have any questions about your health and the risks or benefits of the vaccine, please ask your healthcare provider before you schedule your vaccine appointment.

    Who should not get the vaccine?

    These people should not get the COVID-19 vaccine:

    • Anyone with a severe allergy to any ingredients in the mRNA vaccines.
    • Those younger than 16 years of age.
    • People currently isolating or experiencing symptoms of COVID-19. These people can get vaccinated after they have finished isolation.

    If you have any concerns about a health condition, please ask your healthcare provider before you schedule your vaccine appointment.

    Should older adults get the vaccine?

    Yes, it is especially important for older adults to get the vaccine because they have the highest risk of being very sick or dying from COVID-19. 

    Can pregnant and breastfeeding women get the COVID-19 mRNA vaccine?

    Yes. The Society for Maternal Fetal Medicine, the CDC, and the American College of Obstetricians and Gynecologists (ACOG) have said that pregnant women may be vaccinated if they choose to do so. If you are pregnant or breastfeeding, please discuss the vaccine with your doctor. Pregnant women were not included in the early COVID-19 vaccine studies, but a few participants became pregnant during the studies. As a result, we only have a small amount of data regarding the safety of these vaccines in pregnant women.

    If I already had COVID-19, should I still get the COVID vaccine?

    Yes, you should get vaccinated. Some people can get COVID-19 again, and we do not know how long someone is protected from getting the virus again.

    If you were treated for COVID-19 symptoms 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.

    Can I get other vaccines while I get the COVID vaccine?

    No. You should not get any other vaccines for 14 days before and after you get the COVID vaccine.

    What are the side effects of the vaccine?

    The most common side effects of the vaccine are pain at the site of the shot, tiredness, headache, muscle aches, chills, joint pain, and fever.  These side effects are more common after the second dose and may last a few days.


    The risk of a serious reaction to the COVID-19 vaccine is very low.  The CDC and FDA are closely monitoring the safety of all approved vaccines. As of early January, cases of anaphylaxis (a serious allergic reaction) were occurring about 5.5 times for every 1 million COVID-19 vaccine doses.


    The risk of COVID-19 is much greater than the risk of a serious reaction from the vaccine. As of January 18, there have been 1,515 COVID-19 deaths for every 1 million people in Pennsylvania.

    Can someone get COVID-19 from the vaccines?

    No.  It is not possible to get COVID-19 from the vaccines because they do not contain the live virus that causes COVID-19.


    Should I wait to schedule a screening mammogram following my vaccination?

    The COVID-19 vaccines can cause swollen lymph nodes after the vaccine is administered. This is a natural response and means your immune system is doing its job. However, the enlarged lymph nodes can show up in a screening mammogram leading to a false positive or confusing result, requiring additional and unnecessary diagnostic testing. Therefore, we recommend you schedule your screening mammogram either before receiving your first dose of the COVID-19 vaccine or 4 weeks after your second (final) dose. If you would like to reschedule your screening mammogram, please call Centralized Scheduling at 717-544-5941.


    COVID-19 Vaccine and Allergies

    Is the vaccine safe for me if I have allergies?

    We know that the great majority of people, even those with severe allergies, have tolerated the COVID-19 vaccine. People with allergies to environmental allergens (such as pollen), foods, latex, oral medications and stinging insects can receive the COVID-19 vaccine. The vaccine does not contain egg, gelatin or latex.

    CDC recommends not to receive mRNA vaccine if you had a severe or immediate allergic reaction to any of the ingredients in the vaccine or anaphylaxis (a severe allergic reaction) to the first dose of the vaccine. If you have a history of an immediate allergic reaction to polyethylene glycol (also known as PEG), or to polysorbate, you should not receive the vaccine.

    If you have questions about if you should receive the vaccine, please talk to your primary care provider.

    What is polyethylene glycol?

    Polyethylene glycol (PEG) is a common ingredient in a wide variety of vaccines and FDA-approved medications. It is found in the colonoscopy preparation, Golytely, in the constipation treatment, MiraLax, as well as in IV medications such as PEGylated medications. It is also in a steroid injection, Depo Medrol (methylprednisolone acetate). Reactions to PEG are rare, but anaphylaxis has been reported. Polysorbate is not an ingredient in either mRNA COVID-19 vaccines, but it is closely related to PEG.

    Who may not be eligible or may need further evaluation for the mRNA COVID-19 vaccine?

    According to CDC guidelines, you may not be eligible to get the mRNA vaccine (or a second dose of the vaccine) if you have experienced any of the following allergic reactions.

    • Severe allergic reaction (e.g., anaphylaxis) after a previous dose of an mRNA COVID-19 vaccine or any of its components
    • Immediate allergic reaction of any severity to a previous dose of an mRNA COVID-19 vaccine or any of its components
    • Immediate allergic reaction of any severity to polysorbate
    • A history of an allergic reaction to an injectable medication

    If you have experienced any of these reactions, please talk to your primary care provider before getting a first or second dose of the vaccine.

    If I have allergies, what happens when I receive the COVID-19 vaccine?

    If you decide to get the vaccine at a Penn Medicine Lancaster General Health vaccination site, you will be asked some questions about your allergy history before the vaccination. If you have had anaphylaxis (a severe allergic reaction) due to any cause, the vaccination team will decide if you need longer monitoring, or if you need to see your primary provider or allergy doctor before vaccination particularly if you report a history of an allergy to an injectable medication.

    There are safeguards in place at Lancaster General Health in case anyone experiences an allergic reaction to the vaccine. Everyone is monitored immediately after they receive the shot:

    • At least 30 minutes for people who have a history of severe allergic reactions
    • At least 15 minutes for all other individuals

    What should I do if I had an allergic reaction to the first vaccine shot?

    We have a virtual urgent care service, called Penn Medicine OnDemand, which you can use as a resource at any time if you develop a reaction that concerns you.

    If you received the COVID-19 vaccine and developed a reaction within 4 hours of being vaccinated, you should call Penn Medicine OnDemand at 717-544-2222. Not all reactions are truly allergic reactions; a provider will first get information about your reaction and decide how to best manage it.

    If you have severe symptoms with wheezing, throat tightness, nausea and hives, seek emergency care.

    It is common to experience a reaction (or, side effect that is not considered allergic) to the vaccine. Side effects include fever, chills, muscle aches, headache and soreness at the injection site. These symptoms commonly begin happening at any time point after receiving the shot and typically last 2 to 3 days. If symptoms persist longer or you develop a high fever, please call Penn Medicine OnDemand.

    After Getting the Vaccine

    If I complete the vaccine series, will I still need to wear a mask and social distance?

    Yes, you should continue wearing masks, handwashing, and social distancing after getting the vaccine. This will help bring the pandemic under control. 

    If I complete the vaccine series, will I still need to quarantine?

    • If you were in close contact with someone who has COVID-19, you do not have to quarantine if:
    • You have completed the second dose in a 2-dose series or one dose of a single-dose vaccine
    • It has been at least 2 weeks since your last vaccine dose
    • Your last dose in the vaccine series was within the past 3 months
    • You do not have COVID-19 symptoms
    • If you travel out of state, you should follow state guidance about quarantine during or after travel.

    Vaccine Availability and Distribution

    When will the COVID-19 vaccine be available?

    Penn Medicine and other hospitals across the country have started receiving a small supply of the vaccine. We currently do not have enough supply to vaccinate everyone who is eligible. As vaccine supply increases, we will contact LG Health patients who meet the Department of Health’s eligibility requirements to schedule their vaccine. Please check for updates.

    How will the vaccine be rolled out?

    The Centers for Disease Control and Prevention (CDC) and the Pennsylvania Department of Health have developed a plan to give the vaccine based on the risk of getting the virus. At first, the vaccine will be given to health care workers and nursing home residents and staff. Next, it will be given to people at higher risk because of their age or medical conditions, then to essential workers, and then to the general population. People who have a higher chance of getting very sick or dying will receive the vaccine first. You can view the state of Pennsylvania’s vaccine plan here.

    Will the COVID-19 vaccine be mandatory?

    The COVID-19 vaccine is not mandatory.

    How is LG Health helping to get the vaccine to everyone who wants it?

    County leaders and healthcare providers are committed to making the vaccine available to everyone who wants it. At this time, the supply of the vaccine is very limited. We will continue to provide clear, accurate information about the vaccine and eligibility on our website at This page will be updated regularly. We are also working with a county planning team to plan for a large, centrally-located site to vaccinate large numbers of people each day. Please check for updates.

    Facts about the COVID-19 Vaccine

    Information about the vaccine is available in many languages at the PA Department of Health website. Click “Translate” in the upper right corner to choose your language.

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