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The COVID-19 vaccine is approved. How will we know it’s safe?


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After last week’s emergency approval of the Pfizer COVID-19 vaccine, doses will be arriving at destinations across the US over the next few days. Pfizer’s vaccine, which has been proven to be more than 95% effective, may be the light at the end of the tunnel that many of us have been waiting for since March.  Still, there are questions surrounding the details of the vaccine about which the public is yearning for answers. Our very own infectious diseases experts here at Tufts Medical Center, Helen Boucher, MD, and Shira Doron, MD, are weighing in.

Are “fast-tracked” vaccines safe?  

“A key message is that no vaccine will be recommended that isn’t acceptably safe,” says Dr. Helen Boucher.  

Dr. Boucher points out that there is a general misconception that “fast tracking” means cutting corners in terms of safety, but she says that is not the case. “What ‘fast tracking’ means in terms of speeding up approval has little to do with the actual trials, and more to do with producing the vaccine,” explains Dr. Boucher.  “Pharmaceutical companies involved in the trials are already manufacturing these potential vaccines ahead of knowing whether its vaccine will be approved.  This is done so that if and when a vaccine proves to be both safe AND effective, there are already manufactured doses ready to be administered to the public. Traditionally, vaccines do not go into production until after FDA approval.” 

What does emergency release of a COVID-19 vaccine mean, and would that vaccine be safe?

“Releasing a vaccine in this manner is known as an EUA, or Emergency Use Authorization,” explains Dr. Boucher.  “An EUA is an option the FDA can exercise during a pandemic to make medicines, diagnostic tests or vaccines available. As the name suggests, this is done in case of an emergency, but we would not recommend an EUA-approved vaccine unless we believe it to be safe. In the case of vaccines a request for EUA may be submitted based on 2 months of follow-up safety data. This was selected based on the fact that most vaccine-related adverse events happen within a few weeks of vaccination. The companies involved in the vaccine trials have all signed a pledge stating they will not request approval for a drug that isn’t safe. Patients who take part in these trials are being followed for 2 years as required by the study protocol.

More information about the FDA Vaccine Emergency Use Authorization Process can be found here >

Does is matter which brand name vaccine a person gets?

Initially there will be at least two versions of the vaccine available – one produced by Pfizer, and one produced by Moderna. Dr. Boucher points out that data around efficacy and safety will continue to be reviewed closely. “If things work out as they’re expected to, there should be very little difference,” she says. “Our advice is to get whatever vaccine is offered when it is offered.”

The type of vaccine one receives may be a determination of logistics. The first vaccine, expected to come from Pfizer, requires ultra-cold storage at -70 Fahrenheit and is shipped in cartons that each contain 975 doses. So only medical centers that have a large enough staff and the proper storage equipment, which Tufts Medical Center has, will be able to distribute the vaccine. The further you get away from these types of facilities the harder it becomes to transport and distribute the vaccine efficiently.

From the first vaccine safety trial back in March, there’s certainly been great progress. Since then, 14 vaccines have reached the final stages of testing, including those from pharmaceutical companies AstraZeneca, Johnson & Johnson, and Novavax. While the development of these vaccines have moved at a rapid pace, it is important to remember that these vaccines have, and are still, undergoing the normal rigorous clinical trial and FDA authorization processes. 

Who will be able to get it first? 

The CDC is implementing a phased approach for vaccine distribution, concentrating first on efforts to deploy the limited number of vaccines first made available to populations most at risk. Individual state legislation is responsible for detailed plans around their rollout. As of December 9th, 2020, the phased approach for the state of Massachusetts is as follows:

Phase 1 in order of priority:

  • Health care workers (clinical and non-clinical) involved in direct and COVID-facing care
  • Long term care facilities, rest homes and assisted living facilities
  • Police, Fire, and Emergency Medical Services
  • Congregate care settings (i.e. corrections and shelters)
  • Home-based health care workers
  • Health care workers doing non-COVID facing care

Phase 2 in order of priority:

  • Individuals with 2+ comorbidities (high risk for COVID-19 complications)
  • Early education, K-12, transit, grocery, utility, food and agriculture, sanitation, public works and public health workers
  • Adults 65+
  • Individuals with one comorbidity

Phase 3:

  • Vaccine available to the general public

Do you anticipate a mandate for the COVID-19 vaccines?

“We’ve never seen a national mandate before, but we’ve never been in a situation like this before,” says Dr. Doron. “Still, I do not anticipate a mandate. The real conundrum is when FDA approval or authorization comes, will that be enough for public acceptance and to end hesitancy? We need a significant percentage of the population to step forward and take the vaccine to speed up the end of the pandemic.”

What is mRNA technology and how do we know it is safe?

Both the Pfizer and Moderna are the first vaccines to use messenger RNA – or mRNA technology – which triggers the immune system to produce protective antibodies without using actual virus. mRNA is delivered in the vaccine in lipid-coated nanoparticles, and taken up by the body’s own cells when they manufacture the so-called “spike protein” on the COVID-19 virus. The protein, which is non-infectious, then causes the body to generate protective antibodies to coronavirus itself. Although long term studies are lacking, the clinical trial data has been compelling regarding efficacy and safety. This information has been subjected to the rigorous, independent review here in the US as well as abroad.

Is there anything that people receiving the vaccine should be aware of (potential side effects, etc.)?

Dr. Boucher explains that the vaccine will be provided in two doses with a short waiting period in between. “Some people get side effects after vaccination like a sore arm, some achiness, and maybe a low grade temperature,” she says. “These are very mild per the reports that we’ve seen and last only an average of 1-2 days. Really a small price to pay for a lifesaving vaccine.”

Is there an end in sight to wearing masks and social distancing?

“This vaccine isn’t a magic bullet,” says Dr. Doron. “There will not be enough at first to vaccinate all of the United States so that is why the ACIP is prioritizing groups in phases  , Producing enough vaccine for everyone will take time. You’re not going to see an immediate disappearance of COVID-19 when the vaccine is released.”  

Dr. Boucher says there is a “hard message” she and her colleagues across the country must get across to the public.  “We’re in a better place than we were in March.  Testing is better.  General treatment of patients is better, and there are more medicines coming to assist us.  It’s staggering, however, when you realize 90% of the population still hasn’t been exposed to COVID-19, so to get to a place where we can say masks are no longer required and physical distancing can be relaxed will take a significant amount of time.”  

It’s important to remember that the vaccine is a defense against the disease but not the infection. Both Dr. Doron and Dr. Boucher emphasize the need to continue wearing a mask, social distancing, handwashing and avoiding large crowds, at least until 70% of the population is vaccinated. People may be able to acquire and possibly spread COVID-19 infection naturally but would avoid serious infection due the protective antibodies afforded by the vaccine. 

Still her message is one of hope. “Things are going to get better. This will end. I am hopeful. Realistically speaking, I believe we are looking at another solid year before things will get back to normal.”