FAU Expert Answers Questions about COVID-19 Vaccines

COVID-19, Coronavirus, Vaccines, Frequently-asked-questions, Questions and Answers, Medicine, Public Health

By gisele galoustian | 3/31/2021

Florida Atlantic University’s Joanna Drowos, D.O., M.P.H., M.B.A., associate chair of the Department of Integrated Medical Science, an associate professor of integrated medical science, and a practicing physician at the Marcus Institute for Integrative Health at FAU Medicine, within  the Schmidt College of Medicine, provides answers to some of the most frequently asked questions regarding COVID-19 vaccines.

Drowos is board certified in preventive medicine, family medicine and medical quality. Prior to joining FAU, she served as the center medical director of the Riviera Beach Health Center of the Palm Beach County Health Department. At the health department, Drowos participated in the care of the county’s medically underserved populations addressing various infectious diseases such as HIV/AIDS and tuberculosis. She also served as the director of medical education for the Palm Beach County Health Department’s Preventive Medicine Residency Program from 2009 to 2013.

1.    What exactly do the Covid-19 vaccines do? Will we be able to go back to normal without masks and social distancing?

The COVID-19 vaccine protects vaccinated individuals from developing disease by promoting an antibody response. These antibodies work by neutralizing the ability of the virus to enter a person’s cells and cause disease. The reason that we do not say the vaccine prevents transmission of the virus between people is that this was not studied in the vaccine trials. In clinical trials, patients who were vaccinated did not go on to develop serious disease or die as a result of COVID-19. Therefore, we cannot say yet with any certainty that the vaccines prevent transmission. So everyone, including people who have been vaccinated, need to wear masks and socially distance until we have data that confirms the vaccine prevents transmission or we have enough people vaccinated in the population (70 to 90 percent) so that the virus is no longer a threat.

2.    Which COVID-19 vaccine should I receive?

The United States Centers for Disease Control and Prevention (CDC) does not offer a recommendation to select one vaccine over another. Patients are encouraged to get any COVID-19 vaccine that is available at the time they become eligible. It is not necessary to wait for a specific brand. All of the currently authorized and recommended COVID-19 vaccines are safe and effective.

3.    If I am in remission from an autoimmune disease will the vaccine cause an autoimmune response or cause my immune disease to flare up?

COVID-19 vaccines that are under emergency use authorization (EUA) have been tested for safety and efficacy and have been found to be safe and highly efficacious. There have not been enough people studied with certain conditions, such as autoimmune diseases, to know for sure if they are safe. Therefore, individuals with autoimmune conditions should consult with their primary care physician or specialist for guidance on whether or not to get the vaccine. The CDC provides more information regarding vaccines and autoimmune conditions.

4.    The CDC advises individuals who are allergic to ingredients in the vaccine not to get vaccinated. How do we know what is in the vaccines?

The likely cause of the very few allergic reactions (anaphylaxis or severe allergic reactions) that have been experienced are due to the lipid nanoparticles that facilitate transfer of the mRNA into cells so that the body can make a spike protein for our immune system to make antibodies against it. For the vast majority of individuals, the lipid nanoparticles are benign. For people with severe allergies (e.g. carry an epi-pen), it is advisable to get the vaccine at a medical facility such as a doctor's office or hospital. Note that this type of allergic reaction is very rare .

5.    Is it true the vaccine can make you sterile? I haven't had children yet and I'm afraid to get the vaccine for that reason.

No, there is no evidence or any reason to believe that the vaccine can make anyone sterile.

6.    If I am pregnant or breastfeeding, should I get a COVID-19 vaccine?

Observational studies suggest that pregnant women with COVID-19 have an increased risk of severe illness and poor health outcomes that may impact their health, as well as the health of their baby. The data on the safety of COVID-19 vaccines in pregnant patients are limited, as this population was not part of the clinical trials. Based on current knowledge, experts believe that COVID-19 vaccines are unlikely to pose a risk to pregnant patients or their babies, because the currently authorized COVID-19 vaccines are non-replicating vaccines and cannot cause infection in either the mother or the fetus. It should be noted that the potential risks of COVID-19 vaccines to pregnant women and their babies are unknown because these vaccines have not been studied in this population. Pregnant women may choose to receive a COVID-19 vaccine and may discuss this choice with their health care provider. The decision on whether to get a COVID-19 vaccine should consider the level of community transmission, the patient’s personal risk of contracting COVID-19, the risks of COVID-19 to the patient and potential risks to the fetus, the efficacy of the vaccine, the side effects of the vaccine, and the limited data about the vaccine during pregnancy. Pregnant women who choose to receive COVID-19 vaccines are encouraged to enroll in v-safe, a pregnancy registry to follow outcomes among pregnant women who are vaccinated. Vaccine manufacturers are following outcomes in people in the clinical trials who became pregnant. Based on self-reported information, no specific concerns have been observed among pregnant vaccine recipients included in the v-safe registry. However, longitudinal follow-up is needed to fully evaluate pregnancy and birth outcomes. Clinical trials to evaluate the safety and efficacy of COVID-19 vaccines in pregnant women are underway or planned. There is no recommendation for routine pregnancy testing before receiving a COVID-19 vaccine, and no need to avoid pregnancy following COVID-19 vaccination. Because non-live vaccines pose no risk for breastfeeding mothers or their infants, COVID-19 vaccines are also not thought to be a risk to breastfeeding mothers and their babies. Therefore, breastfeeding patients may choose to be vaccinated. There have not been studies evaluating the safety of COVID-19 vaccines in lactating women or the effects of COVID-19 vaccines on the breastfed infant or milk production or excretion.

7.    If I am planning on getting another vaccine such as Shingrix to prevent the shingles, when will it be safe for me to get a COVID-19 vaccine?

According to the CDC, we do not have enough data on the safety and efficacy of mRNA COVID-19 vaccines administered simultaneously with other vaccines. Therefore, the recommendation is that the COVID-19 vaccine series be administered alone, with a minimum interval of 14 days before or after administration with any other vaccine. In certain emergent situations where the benefits of receiving the vaccine outweigh the potential risks of co-administration (i.e. giving a tetanus-toxoid vaccine as part of wound management) or avoiding barriers or delays to mRNA COVID-19 vaccination (e.g., in long-term care facility residents) and may be given before a 14 day separation. If mRNA COVID-19 vaccines are administered within 14 days of another vaccine, doses do not need to be repeated for either vaccine. That said, it is more important to get the COVID-19 vaccine now and if you or your physician have concerns about getting the two vaccines close together, postpone the Shingrix. Talk to your doctor to help you decide.

8.    What happens if I can’t make my appointment for the second dose of the Pfizer vaccine? Does it have to be exactly 21 days or can it be off a couple days?

The Pfizer vaccine was studied as a two-dose vaccination with the second dose at 21 days after the first dose. While it is best to stick to 21 days because this is how the vaccine was studied, it is okay to get the second dose within 21 to 28 days.

9.    I have heard that if someone has a compromised or weakened immune system, they should not get a COVID-19 vaccine. Can someone with a weakened immune system be safely vaccinated?

The COVID-19 vaccines were not studied in people who are immune suppressed, so the answer is that we do not really know what the safety and efficacy is in people with immune suppressive disorders. What we do know is that in order to mount an effective immune response with vaccination, a working immune system is needed. Therefore, people who have a compromised or weakened immune system may not be able to generate a fully protective immune response to the COVID-19 vaccines. Based on experience with other vaccines of a similar type to the ones currently under emergency use authorization (no live virus), no major side effects or unique side effects have been reported in immunocompromised patients. Your physician may want to do some testing prior to you being vaccinated. Moreover, it is important that you discuss with her or him the risks and benefits to you specifically, which is why I advise speaking with your primary care or specialist physician to determine if you should get the COVID-19 vaccine.

10.   Are the first and second doses of the Pfizer and Moderna COVID-19 vaccinations exactly the same or is the second dose a different composition? 

As far as the COVID-19 vaccine, whether you receive the Pfizer-BioNTech or the Moderna COVID-19 vaccine, the first and second doses are identical. How the vaccines are administered are standardized as far as temperature storage, preparation and dilution, and amount injected from the syringe, and are specific for each manufacturer. This is standardized across all of the sites that are delivering each of the vaccines. If you receive a vaccine from one manufacturer, your second dose should be from the same manufacturer. There are differences in the timing of when to administer the second dose between the two, making it difficult to switch vaccine brands. The studies showing how well the vaccines work were standardized with the same vaccine for both doses, at specific intervals. This led to the recommendation to receive the same vaccine for the second dose that you receive for your first. Receiving the second dose is important, as the first primes your immune system to fight the infection, while the second increases and differentiates the kind of antibodies that you would need in order to be maximally protected.

11.   I have received both doses of my COVID-19 vaccination. In two weeks, am I allowed to be indoors and unmasked with my friends who also have received both doses of their vaccinations?

Vaccination will play an important role in stopping the spread of COVID-19 this year and allowing a return to activities, which we have previously enjoyed. Both the Pfizer/BioNTech and Moderna vaccines showed approximately 95 percent efficacy at preventing symptomatic disease in clinical trials after the second dose. While this is a high number, we should be mindful that they are not 100 percent effective. There is still a small chance one of you could pick up the virus from a vaccinated friend and develop symptoms. Although the vaccines are very good at preventing the severe symptoms that land people in the hospital, experts cannot rule out the possibility that you will develop milder symptoms, which could conceivably become chronic. The risk is low, however, you need to factor in your underlying health, and the risk to you if you were to contract an asymptomatic infection, as well as the risk of spreading infection to others, before making decisions about activity safety post-vaccines.

12.   What should I do if I have an adverse event from receiving a COVID-19 vaccine?

Any adverse event related to a vaccine is reported in the Vaccine Adverse Event Reporting System (VAERS https://vaers.hhs.gov/data.html). The COVID-19 vaccines are relatively new, so as of now, most of the adverse events have been related to anaphylactic reactions to the vaccine. Within four to six weeks after reports are entered, they are de-identified and made available to the public to analyze. You do have the ability to enter your own report and many of us will be following this data over time.

13.   Why isn’t the COVID-19 vaccine a pill instead of a shot?

While oral vaccines are easier to administer, oral delivery of antigens needs to overcome multiple physicochemical and biological barriers in the gastrointestinal (GI) tract. Our GI tracts are designed to provide a biological barrier that protects our bodies from the invasion of pathogenic threats. This includes an environment that is very acidic, which could break down an antigen, as well as challenges in the absorption that would allow our systems to develop the necessary immune response. Our bodies would need a significantly higher dose of antigen to induce an immune response when compared to traditional parenteral immunizations. Currently, the majority of licensed vaccines are administered either by subcutaneous or intramuscular injection.

14.   How long should I wait to get the second dose of the COVID-19 vaccine if I happen to get COVID in between the two doses?

According to the CDC, vaccination of persons with known current SARS-CoV-2 infection should be deferred until the person has recovered from the acute illness (if the person had symptoms) and criteria have been met for them to discontinue isolation. This recommendation applies to persons who develop SARS-CoV-2 infection before receiving any vaccine doses as well as those who develop SARS-CoV-2 infection after the first dose, but before receipt of the second dose (www.cdc.gov/vaccines/covid-19/info-by-product/clinical-considerations.html). As long as the person is no longer symptomatic and able to discontinue isolation, they can have the vaccine, however there is a caveat regarding what kind of treatment they had for their COVID infection. There also are questions about treatments for COVID infection – such as those who have received monoclonal antibodies or convalescent plasma as part of their treatment. In a case where someone has received either of these therapies, per the CDC, they should delay.

15.   If I had COVID-19 and I received monoclonal antibodies or convalescent plasma as part of my treatment, do I still need to get vaccinated and if so when?

Currently, there are no data on the safety and efficacy of mRNA COVID-19 vaccines in individuals who received monoclonal antibodies or convalescent plasma as part of COVID-19 treatment. Based on the estimated half-life of such therapies as well as evidence suggesting that reinfection is uncommon in the 90 days after initial infection, vaccination should be deferred for at least 90 days, as a precautionary measure until additional information becomes available, to avoid potential interference of the antibody therapy with vaccine-induced immune responses. This recommendation applies to individuals who receive passive antibody therapy before receiving any vaccine doses as well as those who receive passive antibody therapy after the first dose but before the second dose, in which case the second dose should be deferred for at least 90 days following receipt of the antibody therapy.

16.   Once I get both doses of the vaccine or the one dose of Johnson & Johnson’s vaccine, will I need to get a booster shot later?

In January, media outlets announced that Moderna planned to offer a third “booster” shot to participants who were a part of their clinical trial. This is part of the ongoing study to determine how long antibodies last and to determine whether it was possible to prolong immunity through giving a third booster, and would need approval from regulatory authorities and time to analyze the data from this change. As of now, the need for and timing of booster doses for mRNA COVID-19 vaccines has not been established for either vaccine. No additional doses beyond the two-dose primary series are recommended at this time.

17.   If I have received both doses of the COVID-19 vaccine, do I have to quarantine if I’m traveling?

Travel can increase your chances of getting or spreading COVID-19, so you will want to take all necessary precautions while making your plans. You can check the CDC’s COVID-19 travel planner to learn about the local, territorial and state requirements for where you are coming from in order to check their requirements for when you return from your trip (www.cdc.gov/coronavirus/2019-ncov/travelers/travel-planner/index.html). It is strongly recommended that individuals who are exhibiting symptoms of COVID-19, or who know or suspect that they have been exposed to COVID-19, do not travel until their periods of isolation or quarantine have ended per CDC guidelines.

18.   I completed my second shot for shingles this week, how long do I have to wait to get the COVID-19 vaccine?

The CDC still recommends that the COVID-19 vaccine series should routinely be administered alone due to the lack of data on the safety and efficacy of mRNA COVID-19 vaccines administered simultaneously with other vaccines. Their recommendation is that you should wait a minimum of 14 days after receiving Shingrix before receiving the mRNA COVID-19 vaccine series. If a COVID-19 vaccine is given within 14 days of another vaccine, you do not need to be revaccinated with either vaccine. You should still complete the vaccine series on schedule. When more data is available on the safety and effectiveness of COVID-19 vaccines given at the same time as other vaccines, the CDC may update this recommendation in the future.

19.   How long does my immunity last once I am fully vaccinated?

Scientists are currently studying both natural immunity and vaccine-induced immunity to learn more about timelines. We do not know how long protection lasts for those who are vaccinated, however, studies are currently looking to answer this question. The CDC will keep the public informed as new evidence becomes available. Getting a COVID-19 vaccine is still a safer choice than risking becoming very ill, being hospitalized or dying from the infection.

20.   I’m in my early 20s and healthy. Why should I get vaccinated?

The complications of COVID-19 are serious and life-threatening and there is no way to know how COVID-19 will affect you. Getting sick also means you could spread the disease to friends, family and others around you. The clinical trials conducted show these vaccines are safe and effective, which is required before their use is authorized. The known and potential benefits of a COVID-19 vaccine outweigh the potential risks of disease, regardless of your age and health status.

21.   Are COVID-19 vaccinations safe for children?

All of the currently available COVID-19 vaccines are authorized for use in adults, except for the Pfizer/BioNTech's vaccine, which is authorized for people ages 16 and older. Children and adolescents outside these authorized age groups should not receive COVID-19 vaccination at this time. Studies are now looking at the safety and efficacy of these vaccines in younger populations and the guidance may change in the future.

22.   What exactly does it mean when they say a COVID-19 vaccine has 97 percent efficacy? 

The efficacy of a vaccine is determined by randomized-control trials, in which volunteers receive either a vaccine or placebo. These trials tell researchers how well the vaccine works in optimal conditions, in which its storage and delivery are monitored and volunteers are healthy. To calculate efficacy rates, scientists compare the frequency of the end-point of the study (in the case of COVID-19 – getting sick or hospitalized) in the vaccinated versus the placebo groups. According to the CDC, vaccine efficacy/ effectiveness is measured by calculating the risk of disease among vaccinated and unvaccinated persons and determining the percentage reduction in risk of disease among vaccinated persons relative to unvaccinated persons. The greater the percentage reduction of illness in the vaccinated group, the greater the vaccine efficacy/effectiveness.

The basic formula is written as:

  • Risk among unvaccinated group − risk among vaccinated group divided by risk among unvaccinated group
  • The numerator (risk among unvaccinated − risk among vaccinated) is sometimes called the risk difference or excess risk
  • Vaccine efficacy/effectiveness is interpreted as the proportionate reduction in disease among the vaccinated group. So a vaccine efficacy/effectiveness of 90 percent indicates a 90 percent reduction in disease occurrence among the vaccinated group or a 90 percent reduction from the number of cases you would expect if they have not been vaccinated. 

 23.  What are the side-effects that I can expect from getting a COVID-19 vaccination? 

While some people have no side-effects from COVID-19 vaccination, you may have some side effects, which are expected as your body is building protection. These side effects may interfere with your ability to complete your daily activities, but they should resolve in a few days.Common side effects at the site where you received the injection include pain, redness and swelling. You may also experience tiredness, headache, muscle aches, fever, chills and nausea. Check with your doctor about whether it is okay for you to take over-the-counter medications such as ibuprofen, acetaminophen, aspirin or antihistamines for any pain and discomfort. It is not recommended that you take these medicines before vaccination for the purpose of trying to prevent side effects. You also are encouraged to apply a clean, cool, wet washcloth over the area where you got the injection, to use or exercise your arm as well as drink plenty of fluids and dress lightly.

24.   Can the vaccines give me COVID-19?

None of the authorized and recommended COVID-19 vaccines or those currently in development in the U.S. contain the live virus that causes COVID-19. This means that a COVID-19 vaccine cannot make you sick with COVID-19. Some of the side effects of the vaccine occur as our immune systems learn how to recognize and fight the virus that causes COVID-19 and may look like an infection, but are actually a normal response to the vaccine and resolve quickly. Some people may report developing COVID-19 even after a vaccine, because it typically takes a few weeks for the body to build immunity after vaccination. It is possible that a person could be infected with the virus just before or just after vaccination and still get sick, or because they have not completed the series and may not have adequate protection.

25.   It seems like they developed these COVID-19 vaccines very quickly. Are they safe?

While using an mRNA vaccine to target COVID-19 specifically is new, the technology behind the vaccine is not new. Prior to receiving authorization, COVID-19 vaccines were evaluated in tens of thousands of participants in clinical trials. The vaccines met rigorous scientific standards for safety, effectiveness and manufacturing quality needed to support emergency use authorization. More than 126 million doses of COVID-19 vaccines were administered in the U.S. from Dec. 14, 2020 through March 22. These vaccines will undergo the most intensive safety monitoring in U.S. history. This monitoring includes using both established and new safety monitoring systems to make sure that COVID-19 vaccines are safe and effective in the long term.

26.   Everyone I know who is vaccinated – including myself – continues to follow the safety protocols that kept us from getting COVID-19 in the first place, before the vaccine. How do we know that this is not what is keeping us safe?

The endpoint of the vaccine trials was to look at serious illness and hospitalization – not whether the vaccines actually stop someone from acquiring the infection at all. We also do not yet have definitive data on whether the vaccine can prevent us from spreading the infection to others. The safety protocols are recommended until we know more about whether the vaccine will protect us from getting a milder form of infection or until we know definitively that vaccines can stop the spread to unvaccinated individuals. So to answer your question – it is both the vaccine keeping you as an individual from getting very sick as well as the other preventive measures to limit further spread and milder illness that are keeping us safe.


The answers to these questions are not meant as medical advice. They are intended to provide information that during a pandemic can change as we learn more about the virus and the vaccines that have been and are being developed. The information provided is the best available as of March 29, 2021. For questions about specific circumstances, consult with a physician.

Joanna Drowos, D.O., M.P.H., M.B.A., associate chair of the Department of Integrated Medical Science, an associate professor of integrated medical science, and a practicing physician at the Marcus Institute for Integrative Health at FAU Medicine, within the Schmidt College of Medicine

Joanna Drowos, D.O., M.P.H., M.B.A., associate chair of the Department of Integrated Medical Science, an associate professor of integrated medical science, and a practicing physician at the Marcus Institute for Integrative Health at FAU Medicine, within the Schmidt College of Medicine