Information about the COVID-19 vaccines for our patients

Watch our webinar from April 21, "Covid-19 Vaccine Updates: What we know now."

You are encouraged to schedule an appointment at a community vaccination site outside of Roswell Park if you have the opportunity to do so. The most important thing is that you get vaccinated and protected from COVID-19 — do not wait for an appointment at Roswell Park if you have an earlier opportunity to get the vaccine. To register online for an appointment at a New York State-run vaccination site, use the Am I Eligible tool at

How does a vaccine work?

Dr. Kelvin Lee explains how vaccines work to protect your body and immune system.


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COVID-19 vaccines FAQs

For Cancer Patients

Dr. Kelvin Lee explains the difference between the Pfizer and Moderna vaccines.

It’s unlikely to affect your cancer treatment, but very little is known right now about the interactions of the vaccine with cancer therapy or with cancer patients. Your cancer treatments would probably have a negative effect on the vaccine, because the vaccine works with your immune system, and most cancer treatments suppress your immune response. It may be that the vaccine won’t work very well in people who are in active treatment.

But even if the cancer treatment decreases the effectiveness of the vaccine by as much as 50%, it’s still worth getting, because if you have at least 50% protection, that is a good thing.

Your type of cancer, the kind of treatment you received or are receiving, or an immune-compromised condition will not automatically exclude you from receiving the vaccine.

The National Comprehensive Cancer Network (NCCN) guidelines, co-authored by Brahm Segal, MD, notes that specific patients should wait to be vaccinated:

  • You must wait at least 14 days after receiving another type of vaccination. If you are planning to receive another vaccine and a COVID vaccine is offered to you, choose the COVID vaccine first. 
  • If you received a blood or marrow transplant or cellular therapy (TCT) recently, you should wait to be vaccinated — at least 100 days after an autologous transplant or cellular therapy, and at least 180 days after an allogeneic transplant. This is to ensure that the vaccine will be as effective as possible.
  • If you’re receiving immunosuppressive therapy for a brief period of time (i.e., for ten days or fewer), you should wait until completion of therapy to be vaccinated. Those on chronic therapy should be immunized as vaccine becomes available to you. 
  • If you’re scheduled to undergo surgery in the near future, the recommended timing of your vaccination will vary based on the type of surgery and how quickly you recover. In most cases, vaccination can be given at least 3 days prior to surgery and after two weeks following surgery. Consult with your medical team for guidance.  
  • If you have received platelet transfusions in the last 30 days, you will need approval from your care team. In addition, if you are being treated for a hematologic malignancy (a blood cancer, such as leukemia) and you have very low platelet counts, please contact your care team. The COVID vaccine is given as an injection into the muscle, and it may cause bleeding. If you have a very low platelet count and are used to getting platelets, you may need platelets before getting the immunization.
  • Patients on anticoagulant therapy (blood thinners) may take the vaccine as long as they are within the therapeutic range. If you are on anticoagulation therapy and have noticeable bruising or bleeding, please contact your Roswell care team for guidance.
  • If you are enrolled in a clinical trial, you will be screened electronically to see if you are in a trial that might make you ineligible for vaccination; this requires special approval from your care team.

If you have specific questions regarding your vaccination status, please read the latest NCCN Guidelines or speak with your doctor and care team.

It is not yet clear whether home-based vaccination will become available. We will answer this question as soon as we have an answer.

The vaccine is free, but an administration cost may be charged, and it is to be covered by insurance.

If you received a blood or marrow transplant or cellular therapy (TCT) recently, you should wait to be vaccinated — at least 100 days after an autologous transplant or cellular therapy, and at least 180 days after an allogeneic transplant. This is to ensure that the vaccine will be as effective as possible.

Your Roswell Park physician or Advanced Practice Professional (APP) will determine your eligibility and recommend the most appropriate timing for vaccination.

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Let's Start to Heal

We trust fact-based research that shows us getting vaccinated will help stop the spread of COVID-19. Get more information about the COVID-19 vaccines, and stay informed.

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Vaccine science & safety


Thousands of people were vaccinated in the phase 1, 2 and 3 studies of the COVID-19 vaccines, and so far, data from those studies indicate that the vaccines are safe. The Food & Drug Administration (FDA) conducts stringent reviews of the vaccines by some of the brightest, most accomplished scientists and health professionals. We can be confident that any vaccine authorized by the FDA is safe and effective.

In addition, a separate COVID-19 Clinical Advisory Task Force has been created in New York State to independently evaluate the safety and effectiveness of the vaccines. Their recommendation will be considered before any vaccine is made available in New York State.

Learn about the benefits of COVID-19 vaccination so you’re ready when the vaccine is available to you.

No, you cannot get COVID from being vaccinated. Learn more about the facts behind COVID-19 vaccines.

The vaccines are not live viruses. They are all either just one or two molecules out of the entire virus or they are a piece of the virus — one or two genes that have been put into another virus that just causes the common cold and that has been inactivated.

No. The COVID-19 vaccines are not live-virus vaccines and cannot affect your DNA.

The side effects recorded during the COVID-19 clinical trials look very much like those associated with other vaccines, such as vaccines for the flu, measles and mumps. It is normal to experience some arm soreness, and some people will experience mild side effects that are a sign that the immune system is working, such as low-grade fever, fatigue, muscle aches or headache.

All vaccines — from the COVID-19 vaccine to the childhood vaccines you received as a kid — have very rare side effects that happen to between one in 100,000 to one in a million patients. Less than 2% of the people who took part in the clinical trials experienced severe side effects, and none were out of the ordinary. There were no autoimmune side effects, for example.

The phase 3 clinical trials included people with high blood pressure, diabetes, emphysema, cardiovascular disease, HIV and other conditions, and in those people the vaccine was shown to be safe and effective. While the data are still being analyzed, there were no clear differences in safety or efficacy for those people.

Here is the FDA's fact sheet about the Pfizer vaccineModerna vaccine and the J&J vaccine. Both include a complete list of ingredients. Mercury and aluminum are not on the lists.

Both are about 95% effective. What does that mean? In the clinical trials, half the patients were given the vaccine and the other half received a placebo (which doesn’t do anything). It is unethical to deliberately expose people to the coronavirus, so researchers just followed up to see which people later became infected.

In the Pfizer/BioNTech trial, of the 43,448 participants (who were 16 years and older), 21,720 received the vaccine and 21,728 received a placebo.

Twenty-eight days after the first dose was given, 170 cases of COVID-19 were observed among those who participated. Of those 170 COVID-19 cases, 162 or 95%  were observed in the placebo group, versus 8 cases in the vaccination group.

In terms of protection from any kind of infection, the straightforward numbers would suggest that the J&J vaccine is less effective when we look at all COVID infections. Both the Pfizer and the Moderna vaccines led to protection of greater than 90%, in the 95% range. With the J&J vaccine, it's closer to 70%.

But the more important thing in terms of public health and personal health is that the J&J vaccine was extremely effective, as effective as Pfizer and Moderna, in terms of preventing hospitalizations and there were no deaths in vaccine recipients who developed COVID.

It usually takes from two to three years to develop a vaccine. The COVID-19 vaccines were developed in six months.

The Pfizer and Moderna vaccines were developed quickly because they used brand-new mRNA technology, which uses instructions for building proteins that can be used to prevent or treat a disease. The same technology was used to develop at least one of the vaccines for the Ebola virus.

The traditional way of making a vaccine was to inoculate chicken eggs with a virus, grow the virus, purify the virus, inactivate the virus, and then make a vaccine out of it. That process is extraordinarily complicated, and that’s why vaccine development took as long as it did.

If the situation weren’t as urgent as it is, the companies who have developed vaccines probably would have taken the standard route. But the advantage of this technology is that it’s incredibly fast — faster by magnitudes than any previous technology we used for developing vaccines.

With Johnson & Johnson, it's a little bit different. It’s not an RNA-based vaccine, but it’s based on virus DNA. The DNA is packaged in an unrelated virus that poses no risk to us, but it's basically housed in this other virus called adenovirus. The DNA that encodes for the spike protein has been engineered, so it's inside the adenovirus. With this vaccine, we don't need to worry about the adenovirus creating infection because it's engineered to not create a problem, but it enables delivery of the spike DNA. And then from the DNA, we go to RNA, from RNA we go to protein and the end result is you're making spike protein.

The regulatory scientists at the Food & Drug Administration are some of the finest scientists and professionals around. They’ve been doing this a very long time. Their interest is in the health of our citizens. Their review of the safety and efficacy of the vaccines is going to be as high-quality as we can possibly get in these rapidly changing times.

Our physician leaders at Roswell Park have reviewed every aspect of safety to determine which patients would benefit from the vaccine, which patients probably should not receive the vaccine at this time, and when it should be given to those who do get it. In addition, as a member of the National Comprehensive Cancer Network (NCCN) — an alliance of 30 of the nation's top cancer centers — Roswell Park is following the recommendations of the NCCN COVID-19 Vaccination Advisory Committee for vaccinating cancer patients. These guidelines are based on the latest medical and scientific evidence.

The clinical trials excluded pregnant women, although some women became pregnant during the trials, and no adverse effects have been reported.

The American College of Obstetrics & Gynecology (ACOG) advises that women who are pregnant or breastfeeding should not be prevented from receiving the vaccine. ACOG also notes that pregnant women are at higher risk for becoming seriously ill if they become infected with COVID-19, and that “Black and Hispanic individuals who are pregnant appear to have disproportionately higher prevalence of COVID-19 infection and death.”

There should be no concern about vaccinated people being around pregnant women, infants or small children. The vaccine is not a live-virus vaccine; it is not infectious and cannot spread to others.

COVID-19 has hit the Black and Hispanic/Latinx communities especially hard. Americans who identify as Black or Hispanic/Latinx represent 33% of all COVID-19 illnesses and 28% of all deaths from COVID-19.

Although the coronavirus vaccines offer protection from COVID-19,  their release has raised many questions, especially for individuals from communities of color. Our COVID-19 Vaccine and Communities of Color fact sheet has the answers you need.

Yes. All vaccine sites are prepared to deal with anaphylactic responses, and the CDC advises sites to monitor people for 15 minutes after vaccination, which is when an allergic reaction is most likely to occur.

Again, if you believe you are eligible to receive the vaccine at this time and have not yet been scheduled for vaccination at Roswell Park, you are encouraged to schedule an appointment at a community vaccination site outside of Roswell Park if you have the opportunity to do so.

Results of the clinical trials indicate that there were no significant side effects for people with general allergies.

Two people in the United Kingdom and two in Alaska did experience anaphylaxis, a serious allergic reaction, within 10 minutes of receiving the vaccine. One of the two in Alaska had no history of allergies. Both people in the U.K. had histories of allergic reactions and carried adrenaline auto-injectors as a result.

The Pfizer vaccine clinical trials enrolled 43,448 participants. Half received the vaccine and the other half received a placebo (which does nothing) in order to compare safety and effectiveness between the two groups. Data show that a few people in both groups experienced what were assumed to be allergic reactions, although the difference between the two groups was slight (.63% vs. .51%).

The phase 3 trial for the Moderna vaccine also had no instances of anaphylactic reactions in the 15,208 subjects who received the vaccine. There has been one incident with the Moderna vaccine being administered under the Emergency Use Authorization.

These anaphylactic reactions have been rare, and have been well managed using the same medical approaches used for other hypersensitivity reactions (for example, peanut allergies, etc.). The current recommendations from the CDC are that unless you are specifically allergic to an actual ingredient in the vaccine itself, you should get vaccinated.

Clinical trials leading up to the FDA’s Emergency Use Authorization of the Pfizer vaccine involved tens of thousands of people, half receiving the vaccine and half receiving a placebo (which does nothing). Significant side effects were very, very rare, and when they did occur, there was no clear evidence that they were caused by the vaccine. Most side effects occurred on the first day and included pain at the injection site, fatigue, headache, muscle aches and some joint pain.

The clinical trials included people who were HIV-positive or who had diabetes, heart disease, liver disease, chronic lung disease, obesity or hypertension (high blood pressure).

With the Moderna vaccine, the side effects were a little more frequent but not more severe.

Please see the question above for specific information about patients who have received a transplant or cellular therapy.

Being immunocompromised will not automatically exclude you from being eligible for the vaccine. Both vaccines were tested in patients with HIV, which is associated with an immunocompromised state. Although the results in those patients were not available when the Emergency Use Authorization was granted, no serious safety concerns were noted.

Neither vaccine was tested in cancer patients in the clinical trials. However, Roswell Park is a member of the National Comprehensive Cancer Network — an alliance of 30 of the nation's top cancer centers — and we are following recommendations of the NCCN COVID-19 Vaccination Advisory Committee for vaccinating cancer patients. 

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Efficacy and Administration


Both the Moderna vaccine and the Pfizer vaccine are two-shot vaccinations. You’ll get the vaccine and then you’ll get a booster later. Right now we don’t know how long that immunity will last. We may need a shot once a year, twice a year or never again. We’ll find out as time goes on.

Both the Pfizer vaccine and the Moderna vaccine require two initial shots for a person to develop immunity. The Pfizer vaccine requires two doses, given three weeks apart. The Moderna vaccine also requires two doses, given four weeks apart.

At the time of your first dose, you will be advised when to return for the second dose, which will be given at the same location.

The Johnson & Johnson vaccine involved one shot. That is the way their respective clinical trials were designed and we judge efficacy based on the clinical trial data.

You will be scheduled for your booster shot at the time of your first shot. It is important that you receive this second dose for maximum protection. There is no evidence to show that protection from the first dose will last if you do not get the second dose. 

More information about the second dose

The second dose of the Pfizer vaccine is given 21 days (three weeks) after the first dose. The second dose of the Moderna vaccine is given 28 days (four weeks) after the first dose. You should receive the second dose of vaccine as close to the recommended date as possible. The Johnson & Johnson vaccine is only one dose.


  • It is permissible to receive the second dose up to four days earlier than the recommended date.
  • If you are unable to receive the second dose by the recommended date (you're late in getting it), you should still get it. You do not need to start over again with another first dose.

Note that COVID-19 vaccine products are not interchangeable. Your second dose must be the same vaccine product. If for some reason you receive a different vaccine for the second dose, you do not need to get another second dose of the original vaccine. 

Fact Sheets

Pfizer-BioNTech Moderna Johnson & Johnson/Janssen (J&J)

There's no basis to pick one vaccine over another. They're all highly effective. When you look at the actual results numerically, the Pfizer and Moderna vaccine prevented more infections than the J&J vaccine, but the J&J vaccine was still very effective. The J&J vaccine was evaluated at a time that there was substantially more COVID infections. But the most important thing is that all three of the vaccines are highly effective at reducing severe COVID, meaning the number of hospitalization and deaths.

Specifically with the J&J vaccine, in the people who were vaccinated, the level of hospitalization is dramatically reduced and there were no deaths.

If one is offered to you, you should take it.

The vaccines produce a rising level of protection. You will get some protection from the first vaccination and more after the second shot. While we don’t know for certain, it looks as if it takes the immune system from two to four weeks to achieve the greatest level of protection.

Yes. The vaccines are not 100% effective, and in the first clinical studies, 5% of people who got vaccinated later became infected with COVID-19. If you do get infected and have symptoms, you can spread COVID-19 to others.

Also, in the clinical trials, only the people who developed symptoms of COVID-19 were tested for the virus. We know that some people  especially younger people  can be infected with the virus but don’t develop any symptoms  the so-called “asymptomatic infections.” We do not yet know if the vaccines protect people from asymptomatic infections, which is important because asymptomatic patients can still spread the virus to others.

Therefore, the key takeaway is this: Continue to wear your mask, wash your hands and social distance EVEN IF you get the vaccine.

For the safety of our staff, patients and visitors, we continue to require that everyone mask up at Roswell Park.

While we continue to be encouraged by the science and the new CDC recommendations released May 13, 2021, that allow vaccinated individuals to put down their masks is most settings, this does not apply in hospitals and healthcare settings at this time. We must continue to protect our most vulnerable patients and we appreciate everyone’s continued cooperation with the important public health measures of masking and physical distancing while at Roswell Park. We remain confident that the continued rollout of the vaccines and growing data about their impact will keep us inching forward toward resuming our normal lives.

The guidance below is provided by the CDC. More information can be found here

Data from clinical trials indicate that the COVID-19 vaccines can safely be given to people who show evidence of having previously been infected with COVID-19. Vaccination should be offered whether you had symptomatic or asymptomatic infection (with or without symptoms). COVID-19 testing to determine whether you are infected now or were infected in the past is not  recommended as part of the process for deciding whether or not you should be vaccinated. 

If you are currently infected with COVID-19, you should not get vaccinated until you have recovered and have met the criteria for discontinuing isolation. This recommendation applies to people who develop COVID-19 infection before receiving any vaccine doses as well as those who become infected after the first dose but before receiving the second dose.

Until the virus is gone, you should not. We don’t know what’s going to happen. And what if half the population doesn’t want to get vaccinated? We cannot let our guard down.

For the safety of our staff, patients and visitors, we continue to require that everyone mask up at Roswell Park.

While we continue to be encouraged by the science and the new CDC recommendations released May 13, 2021, that allow vaccinated individuals to put down their masks is most settings, this does not apply in hospitals and healthcare settings at this time. We must continue to protect our most vulnerable patients and we appreciate everyone’s continued cooperation with the important public health measures of masking and physical distancing while at Roswell Park. We remain confident that the continued rollout of the vaccines and growing data about their impact will keep us inching forward toward resuming our normal lives.

If you have been vaccinated, you will not have a sufficient (>94%) amount of immunity until 2 weeks after your second dose, please continue to be vigilant with masking and precautions.

There are going to be issues with supply-chain shortages and the vaccine-manufacturing process that may be affected as the pandemic gets worse. That’s why all of us need to continue to be vigilant — socially distance, wear a mask, wash our hands. And even though the vaccines are here, they're not going to be available to the general public for months.

The safest thing to do is to get vaccinated as soon as you can and continue following the current safety measures until we get the pandemic under control. Then we can consider lightening things up a little, but until people stop dying, we need to do everything we can to stop this pandemic.

For more information about the COVID vaccines, please visit:

Nobody is claiming that the vaccines are 100% effective. In some of the people who have tested positive after being vaccinated, they may have developed COVID during an early window period, like after the first shot but before the second. They may have already had asymptomatic COVID at the time that they got the first vaccine or the second. Recall, the incubation period can be as long as two weeks. Then there are people who simply got COVID. They got the full vaccine, proper period elapsed, and they got COVID.

There's no question that you're going to reduce the likelihood of getting COVID, and even more important, you will dramatically reduce the likelihood of severe COVID that will lead to hospitalization and death. Just because a vaccine is not 100% effective, it's not an all-or-none situation. It may be partially effective, it may be that you get COVID but not as severe as you otherwise would have had it had you not been immunized. There's benefit even if there is COVID.

So even if you get vaccinated, you still need to wear a mask, wash your hands and practice social distancing.

The expectation is that the vaccines are effective against the variants, but there's variability and geographic diversity in the variants.  The virus can rapidly mutate and there can be a shift in the prevalence between garden variety SARS coronavirus-2 and the variants. There are some data that some of the variants may actually be more aggressive than the original virus. For what we know right now, the vaccine should be effective against variants, but that is not a sure thing and things can change.

According to the Centers for Disease Control and Prevention (CDC), “Experts do not know what percentage of people would need to get vaccinated to achieve herd immunity to COVID-19. Herd immunity is a term used to describe when enough people have protection — either from previous infection or vaccination — that it is unlikely a virus or bacteria can spread and cause disease.”

This will depend primarily on vaccine manufacture and distribution, which may be impacted by the current worsening of the pandemic itself, through disruption of supply chains and essential workforces. It is likely that full vaccination in the U.S. will not occur any sooner than summer 2021 – and possibly significantly later than that.

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