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COVID-19 Vaccine Webinar FAQs

HSS experts Alexandra Grizas (AVP, Infection Prevention) and Andy Miller, MD (infectious disease and internal medicine physician) answered frequently asked questions about the COVID-19 vaccine on a live webinar January 27, 2021 (View webinar). The questions and answers have been summarized and sorted into the following categories that you can jump to below:

For the most accurate and up-to-date information about the COVID-19 vaccines, please reference the CDC site. The information below was published on February 24, 2021.

About the Vaccines

What are the different available vaccines and how do they compare? Is one better than the other?

There are currently 2 COVID-19 vaccines available for use in the US, and they are very, very similar to each other.  One is made by Pfizer and the other is made by Moderna. Both vaccines are given as a shot into the upper arm/shoulder muscle.  The injection itself is just like a flu shot.

Many other COVID-19 vaccines are under development in the US and around the world, such as the ones by AstraZeneca, Novavax, and the Janssen Pharmaceutical Companies of Johnson & Johnson. Preliminary data published in the New England Journal of Medicine show a single shot of Janssen was 66% efficacious. While Janssen is not an mRNA vaccine, like Pfizer and Moderna, it also uses the “spike protein” antigen to induce immunity to the virus that causes COVID-19.

You can see an interesting graphic about the many COVID-19 vaccines in various stages of development from the NY Times.

What is an MRNA vaccine?

Both the Pfizer and Moderna vaccines work the same way.  Both vaccines are made of “messenger RNA (or mRNA)” which is coated in an oily layer – a little bit like an M&M is a chocolate coated in candy.

mRNA is most easily described as “instructions for your body’s cells.” mRNA molecules are how your cells bring information from their DNA inside the nucleus, outside to the rest of the cell, so that proteins can be made.  In this case, with this vaccine, the mRNA contains instructions on how to make a piece of the “spike protein.” And the mRNA never gets to the nucleus. mRNA vaccines do not alter your DNA.

How does the body develop immunity after getting the vaccine?

When you get vaccinated, cells in your muscle that take up the injected mRNA use it to make spike proteins. The immune system, noticing the spike protein, reacts to it. It's that immune response, the immune response getting exposed to and reacting to the spike protein, that builds immunity to the COVID-19 virus that keeps you from getting infected. Your body makes antibodies, B cells and T cells develop, and you become immune to the virus when you are exposed to it. What we know for sure is that both vaccines work extremely well at preventing people from getting ill with COVID-19.

How long does it take for immunity to develop after each of the doses?

1-2 weeks after your 2nd shot, the vaccine will become fully effective. Data from the vaccine trials show that Pfizer vaccine is 95% effective at preventing COVID-19 illness and Moderna vaccine is 94.1% effective.

Do the available vaccines protect against the new strains of COVID-19?

So far, the vaccines still appear VERY effective against ALL the new strains, and these vaccines can actually be changed pretty quickly if adjustments are needed. Right now, no one can say for certain whether all of these new variants will be meaningful or not. But they do remind us that – vaccinated or not – we all need to continue to wear a mask and distance ourselves, and to stay home – all of the things we have been doing for so many months – even though most of us are tired of it by now.

When will those under the age of 18 or 16 (depending on vaccine) be able to get vaccinated?

The answer is: not yet. 

Pfizer has completed enrollment in a study of children between ages 12-15, and we don’t know the results of that study yet.  Moderna, Janssen, Novavax, and AstraZeneca are also planning or conducting similar studies.

We anticipate that studies including younger children will begin soon (perhaps over the next couple of months).  There is still hope that school age children can return to school safely vaccinated in September 2021, but there are unfortunately no guarantees about this yet.

Why is the vaccine not called the Emergency Vaccine any longer? When will the full trial be completed to be approved by the FDA and other similar organizations around the world?

Please see the FDA summary page on Emergency Use Authorization.

The Emergency Use Authorization (EUA) process was established in 2004 and is different than an “FDA approval or clearance.” In an emergency, EUA allows the FDA to make a product available to the public based on the best available evidence at the time, without waiting for all the evidence that would be needed for formal FDA approval. The EUA process includes looking at potential risks and benefits based on the data currently available, and data will continue to be provided to the FDA even after EUA is granted. EUAs are effective until the emergency declaration ends and can also be revised or revoked by the FDA at any time.  After EUA is granted, the FDA also expects manufacturers to continue their clinical trials to obtain additional safety and effectiveness information, and ultimately to pursue licensure (like FDA approval).

What side effects can I expect after receiving the vaccine?

Common side effects include:

  • Pain at injection site
  • Tiredness
  • Headache
  • Fever and chills in about 1/5
  • Injection site swelling or redness
  • Nausea
  • Enlarged lymph nodes


  • Anaphylaxis – approximately 1 in 111,000, perhaps even less often
  • Deaths – as millions of vaccine doses have been given, there have been some rare reports of deaths in people who got vaccinated.  It’s not clear that these deaths were actually linked to the vaccine itself, and that is still under evaluation.  But it is clear that the vaccine is generally extremely safe, and that the risk of death from COVID-19 is much, much higher than any risk from the vaccine.

How should we manage potential side effects?

If you have vaccine side effects, like a sore arm, Tylenol (acetaminophen) or Advil or Motrin (Ibuprofen) can be helpful for pain and fever. It is not recommended that you take anything before getting the vaccine though because you may not have any side effects that warrant taking medications, and we do not fully understand how medications like these interact with the vaccine.

When you get your vaccine, one of the things you will also receive is information about how to report any side effects that you experience. The CDC has developed the “v-safe” program that is a smartphone-based tool that uses text messaging and web surveys to provider personalized health check-ins after you receive a COVID-19 vaccine.

Additionally, everyone who gets the vaccine will be monitored for at least 15 minutes afterwards.  And of course, if you have concerns after then, you should contact your healthcare provider or 911 if you are experiencing an emergency, but that will be a very rare occurrence.

Will we have to get a shot every year as we do with the flu? Will booster vaccines be necessary?

Booster doses might be required in the future, but we do not have this information yet as it is still being studied.

Vaccine Safety

Is the vaccine safe?

Some people are concerned that the vaccine is “too new.” One of the reasons these vaccines have been a scientific success and become available within 1 year is that there was so much engagement and financial investment early on from both the public and private sectors. Additionally, the DNA sequence for the virus that causes COVID-19 was identified very early on and it was shared widely.

Rest assured that both vaccines completed rigorous testing and thus far, with over 104 million doses given around the world (including more than 36 million doses in the US), these vaccines appear to be very safe.

How do we know the vaccine does not cause long term effects?

The COVID-19 vaccines are still new and we do not know everything about them. While a broad range of people took the vaccines safely in the clinical trials, there may be groups of patients that have special risks, and there may be risks that are unknown. We will continue to learn more as more data is gathered and more people are vaccinated.

Should I be concerned about news of severe allergic reactions to the vaccine? I've heard that one of the vaccines is likely to cause a reaction in those with a severe shellfish allergy.  Is this true?

It is important to make sure you do not have serious allergies to the components of the COVID-19 vaccine. Some of the compounds that go into the vaccines include polyethylene glycol and some polysorbates. If there are any questions about allergies, you should talk to your doctor and not receive the vaccine only if there is a high suspicion or confirmation that you are allergic.

There have been many news reports about allergic reactions, and you can rest assured that whenever there is a serious adverse event, healthcare providers are mandated to report it, and the event is investigated to see if there is a causal link.

As of right now, there are only two clear medical reasons why you might not be eligible to get vaccinated:

  • The risk of allergy: Severe allergic reaction (anaphylaxis) to any component of the COVID-19 vaccine (specifically PEG, polysorbates)
  • You’re too young!   Need to be at least 16 years or older to receive the Pfizer vaccine, or 18 years or older to receive Moderna.

After receiving the vaccine, you will be monitored for at least 15 minutes.  If you have a special concern, speak with your healthcare provider before getting the COVID vaccine. You can also let the vaccination center know and ask for longer monitoring after getting your vaccine.

Right now, there is only one reported shellfish allergy.

Should people on immunosuppressive medication take the vaccine? Should people on certain medications not get the vaccine? (Humira, Enbrel, blood thinners)

Even if you are immunocompromised, it is still very important to get the vaccine. In general, immunocompromised people are more likely to get very sick if infected with COVID-19. Make sure to consult with your doctor beforehand to decide the best course of action.

Over time, we are going to learn more about patient groups that have particular benefits or risks from the vaccine. There is still so much left to learn, but so far, the vaccine seems extremely safe and extremely effective.

Will the vaccine interact with medications for those with cancer, are immunocompromised, or who are transitioning? For patients on immunosuppressive meds for RA, is it recommended that those meds be temporarily discontinued for a period of time pre and/or post vaccination? Are the vaccines as effective (94% and 95%) if on Humira for RA?

It’s a great question, and we don’t have a clear answer. Because we know that people on biologic therapies have a lower immune response to some other vaccines, it won’t be surprising if we notice the same about people on Humira and related medicines. But we don’t know yet.

Getting Vaccinated

Can I get COVID-19 from the vaccine?

No. You cannot.

The “spike protein” that gets made through the mRNA vaccines is only 1 piece of the virus. It isn’t a virus. It can’t replicate. It’s just a molecule. On its own, the “spike protein” cannot cause COVID-19 infection.

It is important to remember that while you cannot get COVID-19 from the vaccine (just as you cannot get the flu from a flu shot), none of the vaccines give you 100% protection. As such, it is important to continue with all safety precautions (like wearing a mask and socially distancing) even after you get the vaccine.  It is still that if you do not take all precautions, you could be exposed to someone who is sick with COVID-19 and you could still get infected and spread COVID to others (whether you have symptoms or not). So while you cannot get COVID from the vaccine itself, you still have to be careful in general.

After vaccination, some people will still get COVID-19. There is good evidence that those people are less likely to become very ill, and less likely to pass COVID-19 to others, although this is still ongoing research about these topics.

Should I take the vaccine if I have never taken other vaccines, such as for flu, shingles, and pneumonia?

If you haven't ever had a vaccine, you are still encouraged to go ahead and receive your COVID vaccine. It is also not too late to get the flu and pneumonia shots this season, but you should wait at least 14 days between getting different vaccines.

The chance of severe allergic reaction is extraordinarily low. Additionally, during vaccine distribution, healthcare professionals are available at all vaccine centers to listen to and help with any concerns. Not receiving a flu, shingles, pneumonia, or any other vaccine in the past should not increase your chance of being allergic to the COVID-19 vaccine.

If I have experienced reactions to DPT shot and pneumonia (i.e. fever and swelling), should I receive the COVID vaccine?

Yes, you should still get the COVID vaccine. Fever and localized swelling around the injection site (and sometimes local lymph node, like the one under the armpit) are common side effects of many vaccines, including the COVID vaccine. Most reactions like these only last for a limited amount of time and self-resolve.

It is important to mention that if you have a history of severe allergic reactions, it would be reasonable to speak with your physician (or allergist) to get individualized advice.

Should I space out receiving the flu vaccine (or other vaccines) from the COVID vaccine?

Wait at least 14 days before getting any other vaccine, including a flu or shingles vaccine, if you get your COVID-19 vaccine first. And if you get another vaccine first, wait at least 14 days before getting your COVID-19 vaccine.

If you happen to get a COVID-19 vaccine within 14 days of another vaccine, you do not need to restart the COVID-19 vaccine series and you should still complete the COVID vaccine 2-dose series on schedule.

When more data are available on the safety and effectiveness of COVID-19 vaccines being given with other vaccines, the CDC may update this recommendation.

If the second dose comes later than the 21 day or 28 days (depending on the vaccine), is this cause for concern? How long can you wait between doses?

While you should get the doses at the recommended times, it’s probably not a problem if there’s a bit of a delay between the two.

The CDC currently recommends that the 2nd COVID dose be given no later than 6 weeks (42 days) after the first dose of both Pfizer and Moderna vaccines if it is not possible to follow the recommended 21-day interval for Pfizer and 28-day interval for Moderna. However, if the 2nd dose is given beyond the 6-week interval, you do not need to restart the series.

Should you get tested for COVID-19 before receiving the vaccine?


You should only be tested for the virus if: you think you currently have COVID-19 infection, you have been exposed to someone who has COVID-19, or you are otherwise are advised to get tested (for instance, for travel testing requirements or before receiving medical care). And the vaccine has shown efficacy whether or not you’ve had COVID-19 before or not, so testing for the COVID-19 antibodies before vaccination isn’t recommended either.  

Should you get tested for antibodies after receiving the vaccine?


Antibody testing is not recommended to assess for immunity to COVID-19 after getting the COVID vaccine.

Can I get the vaccine if I have recovered from COVID-19?

Yes, after 3 months.

If you have had COVID in the last 90 days, you should speak to your doctor about getting the vaccine and recommended timing.  Ultimately though, you should still get the COVID vaccine.  We are learning that natural COVID infections appear to produce widely differing levels of immunity, and it is also possible to get COVID more than once, so you should still get the vaccine.

What happens if I get COVID-19 between my 1st and when my 2nd shot is scheduled? Would I need to delay my second shot?

If you currently have COVID-19, you should wait until you have fully recovered and meet criteria to exit isolation before getting the COVID-19 vaccine.

If you get COVID-19 between the 1st and 2nd doses of the COVID vaccine, you should fully recover and follow guidance from your health department and healthcare provider on when you can exit isolation, and then get the 2nd dose of the COVID vaccine.

HSS Patients and Community Vaccination program

Will HSS be providing vaccinations? What does the timeline look like?

HSS is following all New York State Department of Health guidelines to distribute our supply of the COVID-19 vaccine. These guidelines include strict criteria that outline who is eligible to receive it. Our availability depends on the amount of vaccine and guidelines we are provided by NY State.

Will HSS patients be contacted or invited to receive the vaccination at HSS?

We will do our best to communicate with our patients and community, but encourage everyone to check the status and availability of the vaccine on our COVID-19 Vaccine Community page.

Is it safe for me to get the vaccine if I have underlying medical conditions?

There are many people with health concerns who should talk with their doctor before vaccination, as the CDC has advised: 

  • If you had COVID-19 or received COVID-19 antibody therapy in the last 90 days
  • If you’re pregnant, planning on getting pregnant, or breastfeeding.  Most doctors and U.S. organizations think the benefits of vaccination still outweigh the risks, but we advise discussing with your doctor before vaccination.
  • If you have a serious bleeding disorder or are immunocompromised, we still think important to be vaccinated, but talk it over with your doctor beforehand
  • If you have a history of severe allergic reactions to other vaccines, talk with your doctor
  • It may be, over time, that particular patient groups are found to have particular benefits or risks from the vaccine.  There’s much left to learn, but we have been very encouraged by what we know so far

How long do I need to wait after receiving the vaccine to have elective surgery?

For anyone planning to have elective surgery at HSS soon, we are advising our patients to get the vaccine at least 7 days prior to surgery, and to plan to be at least 7 days post-op before getting the 2nd dose.  If you have any specific questions about the timing of your vaccine versus your surgery, please reach out to your surgeon’s office for guidance.

Life after the Vaccine

Do I still have to wear a mask and social distance after being vaccinated? Can I still transmit the virus to others?

We do not yet know the exact answer to whether or not you can still spread COVID-19 around once you have received your vaccine. It is very likely that transmission would be highly reduced, but we still do not have all of the evidence. A new study of the AstraZeneca vaccine shows that transmission is greatly reduced, but it is not eliminated.

The last thing you'd want to do is be in a big group and potentially spread the virus around to other people, or pick up the virus and bring it to your household, work, and others. Social distancing and wearing a mask when you're around people who are from outside your household are going to remain very important for a while.

Will getting the vaccine mean less travel restrictions?

Getting the vaccine will help reduce your risk of becoming infected with COVID-19, but it will be a while before everyone is vaccinated, before we fully understand how long the vaccine provides immunity for, before we know how many people need to be vaccinated to reach herd immunity, and before we understand how well the vaccine prevents the spread of COVID-19. Also remember that the vaccine is not 100% effective at preventing COVID-19 infection. So currently there are no changes in the recommended safety precautions everyone should take, including limiting unnecessary travel or quarantine and testing requirements after travel, even for those who have been vaccinated.


Go to our COVID-19 Vaccine page