COVID-19 Vaccine FAQs

March 9, 2021 Dawn Querns

Widespread vaccination is our best way to end the COVID-19 pandemic. We know you may have questions and concerns as more vaccines become available to the public.

Paul Sax, MD, clinical director of the Infectious Disease Clinic at Brigham and Women’s Hospital and other Mass General Brigham experts answer your top questions about the COVID-19 vaccines.

Why is it important to get a COVID-19 vaccine rather than waiting for herd immunity?

“There are two compelling reasons to recommend vaccination over herd immunity,” said Dr. Sax. “The first is that immunization protects people from COVID-19, which is a potentially life-threatening disease. COVID-19 has a much higher case fatality rate than flu, and even young healthy people can become severely ill.“

Some people with COVID-19 have symptoms that may persist for weeks or months. Common complaints include fatigue, shortness of breath, feeling a racing or pounding heart (also called palpitations), chest pain, trouble concentrating and “brain fog.”

“The second reason to advocate for getting the vaccine is that it will protect others. People with COVID-19 — the actual disease — are highly infectious during the early phases of their illness. This means they can readily transmit (spread) the infection to others,” explained Dr. Sax.

“It is highly likely that immunization will reduce the risk of viral spread. So while we can’t conclude that immunization eliminates this risk — which is why we still recommend masks and physical distancing while case numbers are high — the scientific evidence strongly points to the vaccines reducing it, making all of us safer.”

How do we know the COVID-19 vaccines work?

The Pfizer, Moderna and Johnson & Johnson COVID-19 vaccines have all proven to be extremely effective.

According to Phase 3 clinical trials, the Pfizer vaccine is 95 percent effective 7 days after the second dose. The Moderna vaccine is 94 percent  effective 14 days after the second dose. These results were consistent across gender, age, race and ethnicity. In U.S. and global studies, the Johnson & Johnson vaccine was 85 percent effective against severe disease. It also provided 100 percent protection against hospitalization and death from COVID-19.

The Pfizer vaccine is authorized for emergency use in those 16 and older. The Moderna and Johnson & Johnson vaccines are authorized for emergency use in those 18 and older.

NOTE: Effective April 13th, Mass General Brigham has paused administration of the Janssen (Johnson & Johnson) vaccine. The U.S. Centers for Disease Control and Prevention and the Food and Drug Administration jointly recommended that administration of the Johnson & Johnson vaccine be paused out of an abundance of caution, while both entities review data, involving six reported U.S. cases of a rare, severe type of blood clot out of the nearly 7 million people who received the vaccine. For the most up-to-date information on the COVID-19 vaccine please visit:

Did the Brigham lead any of the COVID-19 vaccine trials?

Yes. Leadership at the COVID-19 Prevention Network (CoVPN) chose Lindsey Baden, MD, director of the Brigham’s Center for Clinical Investigation (CCI), as the co-principal investigator of an mRNA Phase 3 vaccine trial. The trial evaluates the effectiveness and safety of the Moderna vaccine and its ability to prevent COVID-19 illness. Watch our video to learn more.

Can I get COVID-19 from a vaccine?

No. The vaccine does not contain the whole or live virus. This means it can’t cause COVID-19.

What are mRNA vaccines?

Both the Pfizer and Moderna vaccines are mRNA vaccines. While the mRNA vaccine is a new kind of vaccine, researchers have been studying and working on them for many years.

When you get an mRNA vaccine, it gives your cells directions on how to make the COVID-19 proteins found on the outside layer of the coronavirus (also called spike proteins). Your immune system can then make antibodies to these proteins, which protects you from getting infected with COVID-19.

The mRNA from the vaccine never enters the nucleus of your cells and doesn’t get into your DNA. Your cells break down and get rid of the mRNA soon after they’re finished using the instructions. The Centers for Disease Control and Prevention (CDC) has information about mRNA vaccines.

How many doses of each COVID-19 vaccine do I need?

The number of doses you need and timing between doses depends on the vaccine you receive.

Why is it important that people get their second dose of the Pfizer or Moderna vaccines?

“The first dose of the vaccine “primes” the immune system to respond to the vaccine. The second dose “boosts” it, greatly increasing antibody responses,” explained Dr. Sax.

“Such a strong antibody response is thought to correlate with how well and how long we’ll be protected from getting COVID-19 in the future,” he added. “It’s likely especially important in those who might have a less robust immune response to vaccinations, such as older people and those who have weakened immune systems.”

What are COVID-19 variants?

Viruses constantly change through mutation. Sometimes new variants emerge and disappear. Other times, new variants emerge and persist. Multiple variants of the virus that causes COVID-19 have been documented in the United States and around the world during this pandemic.

The CDC reports that multiple variants are spreading around the world. Some of these variants seem to spread more easily and quickly than other variants, which may lead to more cases of COVID-19.

How can widespread vaccination help prevent the spread of variants?

Dr. Sax expects widespread immunization will lead to decreased numbers of people with COVID-19 and less circulating virus. With less virus out in the community reproducing, the virus has less of an opportunity to evolve into variants.

I already had COVID-19. Should I get vaccinated?

Yes. When it becomes available to you, you can still get the vaccine if you’ve had COVID-19 and have recovered. If you’re actively sick with COVID-19 or have symptoms that could be from COVID-19, you shouldn’t get the vaccine at this time.

How long will immunity last after I get vaccinated?

We don’t know this yet. The clinical trials will continue to monitor participants to see how long protection lasts. We will provide updated information as it becomes available.

Because we don’t yet know how long immunity will last, it’s still important to wash your hands, wear a mask and physically distance.

What are the side effects of the COVID-19 vaccine?

Some people have side effects after receiving the vaccine. Most mild side effects resolve within a day or so.

The most commonly reported symptoms are:

  • Pain at the site of vaccination
  • Swollen lymph nodes in the same arm as the injection
  • Chills
  • Fatigue (feeling very tired)
  • Fever
  • Headache
  • Muscle pain or joint pain
  • Nausea or vomiting

If you get the vaccine but don’t have side effects, there’s no reason to worry.

“As far as we know, this protection applied across all the study participants, even those who had few or no side effects from the vaccine,” said Dr. Sax.  “As a result, at present there is no recommendation to repeat the vaccine or do additional testing afterwards if a person has no side effects.”

How can I get my COVID-19 vaccine at Mass General Brigham?

Mass General Brigham is offering limited new appointments for the COVID-19 vaccine to patients who are eligible under the current phase of the state’s vaccine distribution plan. Due to continued vaccine supply constraints, Massachusetts has been working to continue to streamline COVID-19 vaccine distribution and to align hospital and health system needs to support the state’s rollout.

Mass General Brigham contacts eligible patients through the patient portal known as Patient Gateway, email, or text message to schedule vaccine appointments. All vaccine appointments are scheduled through a central scheduling center. Please do not contact your doctor’s office about vaccine appointments.

Based on supply, Mass General Brigham invites eligible patients to schedule appointments using a fair, random process. It may take time before you receive your invitation and are able to schedule your appointment. Please be patient. The team is working closely with state officials to ensure that Mass General Brigham receives a steady supply of vaccine to schedule appointments every week.

Get the latest COVID-19 vaccine distribution information.

Last reviewed: April 14, 2021

The post COVID-19 Vaccine FAQs appeared first on Brigham Health Hub.

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