In December 2020, the FDA approved two COVID-19 vaccines (Pfizer/BioNTech and Moderna) for Emergency Use Authorization, both of which are beginning to be distributed across the country. Mark Poznansky, MD, PhD, director of the Vaccine & Immunotherapy Center at Massachusetts General Hospital offers guidance and answers to common questions regarding this latest development in the fight against COVID-19.

Are there any COVID-19 vaccines approved by the Food and Drug Administration (FDA)?

Currently, the FDA has given Emergency Use Authorization for the Pfizer/BioNTech and Moderna vaccines. Both are currently being rolled out for broader use across the United States.

Learn more about Emergency Use Authorization >

Who can get vaccinated right now?

The distribution of vaccines will be in accordance with the guidelines from the Advisory Committee on Immunization Practices (ACIP) as well as Massachusetts’ COVID-19 Vaccination Plan.

There are four recommended phases of vaccine distribution. The ACIP released that Phase 1a of vaccine distribution will include health care workers and long-term care facility residents. Given that guidance, the Massachusetts Department of Public Health is prioritizing hospitals, long term care facilities—including skilled nursing facilities—emergency medical services and other health care providers for recruitment and enrollment in the Massachusetts COVID-19 Vaccination Program.

Learn more about Massachusetts' Vaccine Distribution Plan >

When will I be able to get vaccinated against COVID-19?

Frontline health care workers, residents and staff of skilled nursing facilities and assisted living residences are currently being vaccinated as part of the first phase. Massachusetts estimates that the general public can get the vaccine between April-June 2021. If you are higher risk, are 65 or older, or work in certain jobs like education, transit or public works, you might receive the vaccine sooner. The current phases of COVID-19 vaccination and the approximate timelines for residents of Massachusetts are detailed here.

Will the COVID-19 vaccine be safe and effective?

Yes. In the U.S. the FDA reviews data collected throughout the development of the vaccine and from clinical trials before approving the vaccine for use. Both vaccines that received Emergency Use Authorization from the FDA have been shown in clinical studies to be more than 94% effective. As people receive the vaccine, the FDA continues to closely monitor its safety and effectiveness.

How many shots will I need to get?

The Pfizer/BioNTech and Moderna vaccines both require two shots, or doses. The Pfizer/BioNTech vaccine requires 21 days between the first and second dose; the Moderna vaccine requires 28 days between the first and second dose.

Is one of the COVID-19 vaccines better than the other? Will I have a choice of which vaccine I receive?

No. Both vaccines given Emergency Use Authorization have been shown in clinical studies to be more than 94% effective. Both vaccines are currently being shipped across the nation and people receiving the vaccination will not have the option to select which vaccine they receive. Once you receive your first shot, your second shot will be from the same manufacturer, i.e. if your first shot is from Pfizer/BioNTech, your second dose will be as well.

How much will a vaccine reduce the risk of COVID-19 and its complications?

Both vaccines that received Emergency Use Authorization are mRNA (messenger RNA). Typically, a vaccine trains your body to recognize and respond to proteins produced by a bacteria or virus. mRNA vaccines trick your body into producing the protein itself which causes your immune system to detect these proteins and defend itself, without risking the serious consequences of getting sick with COVID-19.

While the vaccine will reduce the risk of the vaccinated person becoming seriously ill with COVID-19, we do not yet know whether the Pfizer/BioNTech or Moderna vaccines will reduce transmission of the virus from one individual to another. We will be learning this as the vaccines are rolled out to more and more individuals.

Could I have an adverse reaction or side effect from the vaccine? What should I do if I experience one?

Based on what we know so far, many people will have mild, short-term side effects after getting a COVID-19 vaccine including:
  • fever
  • fatigue
  • headache
  • muscle pain 
  • joint pain
Some patients may have swelling and redness at the site of the injection that can last for a few days. These are not allergic symptoms but part of the immune response to the vaccine.

In rare instances, vaccines can cause severe physical reactions. If you experience an adverse reaction or side effect, you should contact your physician. Additionally, the Centers for Disease Control and Prevention (CDC) and FDA encourage the public to report possible side effects (called adverse events) to the Vaccine Adverse Event Reporting System (VAERS). Reports to VAERS help the CDC monitor the safety of vaccines. Safety is a top priority.

Learn more the difference between a vaccine side effect and an adverse event >

If I get the vaccine do I still need to wear a mask and practice social distancing?

Yes. According to the CDC, there is not enough information currently available to say if or when the CDC will stop recommending that people wear masks and avoid close contact with others to help prevent the spread of the virus that causes COVID-19. Additionally, how many people get vaccinated and how the virus is spreading in communities will also impact the effectiveness of the vaccine.

How soon after getting the vaccine am I protected?

The Pfizer/BioNTech vaccine has been shown to start providing some protection for the vaccinated person within 10 days of receiving the first dose. However, it remains necessary to receive the second dose in order for the vaccine to be maximally effective in protecting the vaccinated person. It will remain important for vaccinated individuals to continue wearing masks and following social distancing guidelines to help prevent the spread of the virus to other individuals.

Where can I find more information?

The CDC provides additional information on COVID-19 vaccines and responses to common questions.