Updated on 11/3/2021. COVID-19 is an evolving topic and information may change. Most of the information comes from the Centers for Disease Control and Prevention (CDC) and the Public Health Communications Collaborative (unless otherwise noted). 

Vaccine Information, Safety & Benefits

How were the COVID-19 vaccines created? 

  • The technology around the mRNA (Pfizer and Moderna) vaccines has been in development for decades, but was brought to the market for the COVID-19 pandemic. The vaccine uses mRNA provides instructions to our immune system on how to recognize and fight against the COVID-19 virus should it come into contact with it. This does not alter your DNA. Learn more through this video by Johns Hopkins School of Public Health

  • The Johnson and Johnson vaccine uses an adenovirus technology. The virus has been altered so it can't make you sick, replicate or enter into your DNA. Learn more in this video from the Mayo Clinic.

Are the vaccines safe?

  • All COVID-19 vaccines have been rigorously tested and reviewed. The vaccine’s clinical trials three-phase process was detailed and thorough, and no shortcuts were taken. 

  • More than 150,000 people participated in U.S. clinical trials of the vaccines, and now, hundreds of millions of vaccine doses in the U.S. have been safely administered.
  • As with all vaccines, there will be ongoing monitoring for adverse events among people who are vaccinated into the future.
  • Learn more about the ingredients of each approved vaccine at the CDC's FAQ page.

Are the vaccines effective? 

  • All COVID-19 vaccines currently authorized for use in the United States helped protect people against COVID-19, including severe illness, in clinical trial settings. Studies that have looked at how COVID-19 vaccines work in real-world conditions (vaccine effectiveness studies) have shown that these vaccines are working well.
  • People with moderately to severely compromised immune systems are especially vulnerable to COVID-19, and may not build the same level of immunity to 2-dose vaccine series compared to people who are not immunocompromised. Therefore, 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 in order to improve immunocompromised people’s response to their initial vaccine series.
  • Booster shots are now recommended for certain groups of at-risk people to help maintain strong immunity. Studies show that after getting vaccinated against COVID-19, protection against the virus may decrease over time and be less able to protect against the Delta variant. Although COVID-19 vaccination for adults aged 65 years and older remains effective in preventing severe disease, recent data suggest vaccination is less effective at preventing infection or milder illness with symptoms. Emerging evidence also shows that among healthcare and other frontline workers, vaccine effectiveness against COVID-19 infections is decreasing over time. This lower effectiveness is likely due to the combination of decreasing protection as time passes since getting vaccinated (e.g., waning immunity) as well as the greater infectiousness of the Delta variant.

Who is eligible for the vaccine?

  • The Pfizer vaccine is approved for everyone 5 years of age and older.
  • The Moderna and Johnson & Johnson vaccines are currently approved for those over the age fo 18.

If I was already infected with COVID-19, do I still need the vaccine? 

  • Even if you have already had COVID-19, vaccination is an important step to protect yourself and those around you. One study showed that unvaccinated people who have had COVID-19 are still twice as likely as vaccinated people to get COVID-19 again. 

What are the side effects of getting the vaccine?

  • Side effects are like other common vaccines. The most common side effects are pain/redness at the injection site, headache, fatigue, muscle/joint aches and low-grade fever.

  • Most side effects last less than 24 hours and those ages 55 and older reporter fewer side effects.

  • For more information, read the CDC guidance on side effects.

Can you get other vaccines at the same time or close to getting the COVID-19 vaccine?

  • Yes, you can get a COVID-19 vaccine and any other vaccines, including a flu vaccine, at the same visit. 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.

Is the vaccine free?

  • Yes, COVID-19 vaccines are available for everyone at no cost, including the Pfizer-BioNTech Vaccine for children ages 5 through 11 years. COVID-19 vaccines will continue to be given to all eligible people living in the United States, regardless of insurance or immigration status.

Can you still get sick with COVID if you are vaccinated? 

  • Vaccine breakthrough cases are expected. COVID-19 vaccines are effective and are a critical tool to bring the pandemic under control; however, no vaccine is 100% effective at preventing illness. The risk of developing a severe case of COVID-19 or being hospitalized is significantly reduced for vaccinated individuals.

Can a person who is trying to get pregnant, is pregnant or breastfeeding receive the vaccine?

  • Pregnant women are at a higher risk to get severely ill with COVID-19 compared with non-pregnant women, which can cause fetal complications. The CDC has issued a health alert recommending those who are pregnant, recently gave birth, are breast-feeding, or trying to become pregnant receive a COVID-19 vaccine as soon as possible. 
  • Data from thousands of people who are pregnant, breast-feeding and those who became pregnant after vaccination confirms that the COVID-19 vaccine is safe and effective before, during and after pregnancy. Data shows no increase in adverse outcomes in pregnant women who receive the COVID-19 vaccine. There is also no evidence linking vaccines to infertility. 
  • The risks of COVID-19 infection outweigh any known or potential risks of vaccination while pregnant or trying to conceive. See more information from the CDC and this shared decision making tool from UMass Medical School.

What can fully vaccinated people do?

  • People are considered fully vaccinated 2-weeks after their second dose of an mRNA vaccine (Pfizer or Moderna) or a single dose of the Johnson & Johnson vaccine. Fully vaccinated people can:

    • Participate in many of the activities that they did before the pandemic.

    • Resume domestic travel and refrain from testing before or after travel and from self-quarantine after travel.

    • Refrain from testing before leaving the United States for international travel (unless required by the destination) and refrain from self-quarantine after arriving back in the United States.

    • Refrain from routine screening testing if feasible.

    • You will still need to follow guidance issued at a workplace and local businesses.

Trust Transfer Project

Taking precautions is still important even with full vaccination status:

  • Wear a mask in indoor public settings, especially in high transmission communities. Both the Department of Public Health and CDC advise fully vaccinated individuals wear a mask or face covering when indoors (outside of your home) if you have a weakened immune system, are at increased risk for COVID-19, or if someone in your household is at increased risk or unvaccinated. 
    • Wear well-fitted masks when visiting indoors with unvaccinated people. 

    • Avoid indoor large-sized in-person gatherings

    • Get tested if experiencing COVID-19 symptoms or have had exposure to someone with COVID-19

    • Follow guidance issued by individual employers

    • Follow CDC and health department travel requirements and recommendations

  • In Massachusetts, masks continue to be required in certain settings, whether you are vaccinated or not:

    • On public and private transportation,

    • Inside K-12 public schools, collaboratives, approved special education schools,

    • Inside childcare programs,

    • In health care facilities and provider offices,

    • In congregate care settings,

    • In health care and rehabilitative day services and programs.

Booster Shots

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Why are boosters needed?

  • COVID-19 vaccines continue to offer highly effective protection against hospitalizations and severe outcomes for people who are fully vaccinated. However, the scientists and medical experts who developed the COVID-19 vaccines continue to closely watch for signs of waning immunity, how well the vaccines protect against new mutations of the virus, and how that data differs across age groups and risk factors. 

  • Protection against the virus may decrease over time and be less able to protect against the rampant Delta variant for more vulnerable groups of people. A booster shot will help to maintain strong antibody protection against COVID-19.
  • Booster doses are common for many vaccines.

Who is eligible for a booster shot? 

If you live in Massachusetts, anyone over the age of 18 years old is eligible for a booster shot. Everyone can choose which brand of booster they prefer to get. 

  • For Moderna and Pfizer recipients, you are eligible after 6 months since getting vaccinated.
  • For Johnson & Johnson recipients, you are eligible after 2 month since getting vaccinated. 

**Please note that other states may have differing eligibility and follow the CDC's guidance

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Can I mix and match my COVID-19 vaccine and booster?

  • Yes. The CDC’s clinical guidance advises people to get the same booster as their initial vaccine, but allows people to mix and match if they have a different preference. Mixing and matching COVID-19 vaccines refers to getting a different COVID-19 booster than the initial vaccine (e.g. getting a Pfizer booster after the Moderna vaccine, or a Moderna booster after the J&J vaccine). 

  • If you have questions about your eligibility for booster doses or which booster you should get, speak to your health care provider.

Am I still considered “fully vaccinated” if I don’t get a booster shot?

  • Yes. Everyone is still considered fully vaccinated two weeks after their second dose in a 2-shot series, such as the Pfizer-BioNTech or Moderna vaccines, or two weeks after a single-dose vaccine, such as the J&J/Janssen vaccine.

For more information on the COVID-19 booster shots, please refer to the following resources:

Vaccine for Children & Youth

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Which children are eligible for the vaccine?

  • The Pfizer-BioNTech COVID-19 vaccine, now known as Comirnaty, is approved and available for children ages 5 and older through emergency use authorization (EUA).

  • The vaccine requires 2 doses spaced 3 weeks apart. Kids 12 years and older receive the same sized dose as adult, while kids 5-11 years old receive a 1/3 the size of an adult dose. COVID-19 vaccine dosage does not vary by patient weight but by age on the day of vaccination.

  • If your child has a significant health issue – such as those resulting in a compromised immune system — check with their physician to determine if they should be vaccinated.
  • Moderna has also applied for authorization for its vaccine for 12- to 15-year-olds, and that data is currently under review. Moderna is also conducting clinical trials on its vaccine for kids 5-11 years old.  

Why should children be vaccinated? 

  • Children can still be infected with COVID-19, get severely sick from it, and spread it to others. Widespread vaccination is a critical tool to help stop the pandemic. Getting vaccinated will help children protect their family and community, as well as get back to the things they have missed: in-person school, playing with friends, and participating in sports activities. 

Is the vaccine for kids effective?

  • Clinical trials show that the Pfizer COVID-19 vaccine is over 90% effective at preventing COVID-19 in children ages 5 through 11 years.

Is the vaccine safe for youth?

  • Yes. The FDA and CDC have carefully reviewed the clinical trials with over 3,000 kids for the Pfizer’s COVID vaccine, and it has been proven to be safe and effective for children 12 and older. Serious side effects were rare. The vaccine goes through the same testing and clinical trials as all vaccines and no serious safety concerns have been identified. COVID-19 vaccines have undergone—and continue to undergo—the most intensive safety monitoring in U.S. history.

What are the side effects for children? 

  • Children may experience mild side effects, such as soreness in the arm, fatigue, headache, or a slight fever, and most will pass in one to two days.  These side effects are normal signs that the body is building protection.
  • Serious side effects are rare and treatable. COVID-19 disease poses a higher risk of serious side effects than the vaccine. 
  • One side effect that parents and youth may feel concerned about it myocarditis or pericarditis (heart inflammation).  These reactions are rare; in one study, the risk of myocarditis after the second dose of Pfizer-BioNTech in the week following vaccination was around 54 cases per million doses administered to males ages 12–17 years. Reported cases have occurred predominantly in male adolescents and young adults age 16 and older. Onset was typically within several days after mRNA COVID-19 vaccination, and cases have occurred more often after the second dose than the first dose. Patients who sought medical care for myocarditis/pericarditis responded well to medications and rest and had prompt improvement of symptoms. CDC and its partners continue to investigate these reports of myocarditis and pericarditis following mRNA COVID-19 vaccination to monitor safety.
  • Parents/caregivers can enroll their child in v-safe, a free, easy-to-use smartphone-based tool that uses text messaging and web surveys to provide personalized health check-ins. Through v-safe, you can report how your child is feeling after vaccination.
  • CDC continues to recommend COVID-19 vaccination for everyone age 12 and older, given the risk of COVID-19 and related, possibly severe complications, such as long-term health problems, hospitalization, and even death. See the CDC's updated information on the clinical considerations on myocarditis and pericarditis after receipt of mRNA COVID-19 vaccines among adolescents and young adults.

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?

  • As opposed to many medications, 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-BioNTech COVID-19 Vaccine for their second dose, they do not need to repeat the dose.

Can the COVID vaccine impact child development?

  • There is no clinical evidence to suggest COVID vaccines have effects on puberty or fertility.

Is it safe to co-administer COVID-19 vaccines with other vaccines, like flu?

  • Yes, if a patient is eligible, both flu and COVID-19 vaccines can be administered at the same visit, as recommended by CDC and ACIP. In addition to flu vaccine, COVID-19 vaccine can be given with other vaccines as well.Does the vaccine require parental consent? 
  • In Massachusetts, a legally authorized representative (usually a parent or guardian) must give permission (also called consent) for vaccination for under 18 years of age, such as by completing a written consent form that the minor can bring to their vaccination appointment. Please contact the vaccination location for more information on written consent, or download a copy of the consent form. 
  • The parent or guardian does not need to go with the minor to their vaccination appointment to give consent. If the parent or guardian is not accompanying the minor, they should download and complete a pre-vaccination screening form, available at mass.gov/CDCScreeningForm. The form is available in several languages.

  • Parental consent laws may vary in other states.

What can parents do to help kids understand the pandemic and offer support?

  • Below are some important reminders on how to support kids. Also, follow these great tips on how to talk with kids about the pandemic.
  1. Make kids feel safe. Stay calm and offer reassurance.
  2. Give them facts and let them lead the discussion. Don't overwhelm them with information they didn't ask for.
  3. Give them control and power where possible.
  4. Let them know what to expect.
  5. Empathize and allow them to express a range of emotions without judgment.
  6. Set your expectations and goals to match the child's developmental stage and temperament.
  7. Try to maintain a routine.
  8. Model behavior you want to see.
  9. Take care of yourself.

Where will vaccines for younger children be available?

  • Pediatricians, pharmacies, and health centers are all places that will administer the COVID-19 vaccine to children. Vaccine providers will also be partnering with schools, districts, and communities to host pediatric vaccination clinics. You can look for locations near you using the MA Mass VaxFinder tool or call your pediatrician. 

What is the status of a vaccine for children under 5 years old? 

  • Clinical trials are currently underway for a vaccine for children under 5 years old. There is no vaccine approved for these younger children yet.

For more information regarding vaccines for children, go to: