Frequently Asked Questions
December 16, 2020

The following Questions and Answers were written based on guidelines of the Center of Disease Control (CDC), the Mayo Clinic and NorthShore University Health Systems as of December 16, 2020.

Download this FAQ (PDF) here

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How do the Pfizer and Moderna vaccines work?
Both are forms of a new type of vaccine that involves injecting mRNA, which replicates the spike protein on the COVID-19 virus. Once you’re injected with the vaccine, your body begins to manufacture the same spike protein to create antibodies to fight it. If you’ve taken the vaccine and are later exposed to COVID-19, the antibodies created inside your body will keep the virus from entering the cells and causing an infection.

Is it a live vaccine?
No. The two vaccines with EUA contain the virus mRNA (which is like a recipe) for the spike protein on the virus.

Can I get COVID-19 from the vaccine?
No. While the vaccine doesn’t contain either live or dead virus, you may develop “flu-like” symptoms such as tiredness, fevers or headaches after receiving one or both doses of the vaccine but these usually resolve within three days.

If someone has previously had COVID-19, should they get the vaccine?
Due to the severe health risks associated with COVID-19 and the fact that re-infection is possible, people may be advised to get a vaccine even if they have been sick with the virus before. If you have had an infection in the previous 90 days, there are differing opinions on whether or not you will need to wait for 90 days after you have recovered from your COVID infection.

What if I’m immune compromised or have an autoimmune disorder. Would it be optimal for me to get vaccinated now or should I wait?
For people who have immunodeficiencies, the COVID-19 vaccine likely will be as effective as it is for the general population. Experts in the field believe that since both vaccines use mRNA—and not live virus—the injection would potentially be suitable for immune-deficient patients. It’s still unclear how the vaccine will work for those who have antibody deficiencies, as they could likely have an incomplete response. Immune-compromised individuals should discuss with their physician before deciding on whether to get vaccinated.

Are there any individual factors that make me ineligible to receive the vaccine at this time?
The CDC’s Advisory Committee for Immunization Practices also has published its guidance on special populations, and it supports offering COVID-19 vaccine to all individuals age 16 and older. The only absolute contraindication is for individuals with a known anaphylactic reaction to any of the components in the vaccine, in particular to polyethylene glycol.

I understand there are two doses of the vaccine required, why is that? How long do I need to wait before getting the second dose?
Yes, you will need to take both doses of the vaccine from the same manufacturer administered either 21 or 28 days apart. This double dose allows your body to develop a stronger immune response to counter a future infection. Your body also needs the extra exposure time to learn how to most effectively fight off exposure to the virus.

What do we know about the vaccines’ efficacy?
The data submitted show that the Pfizer and Moderna vaccines have an efficacy of at least 90 percent after 2 doses. A vaccine efficacy of 90 percent means that the vaccine will protect 9 out of 10 individuals from contracting the infection. The data also show that vaccinated individuals have more mild symptoms if infected and didn’t need to be hospitalized as often.

Can the vaccinated person still spread COVID-19 once the vaccine takes effect?
We don’t have data on whether receiving the vaccine keeps you from spreading the virus to others. This means that everyone—whether they have received the vaccine or not—will need to continue to wear facemasks, practice physical distancing and good hand hygiene.

Is the vaccine safe? What is the science data behind it?
The Pfizer and Moderna vaccines are being distributed under Emergency Use Authorization (EUA) from the Food and Drug Administration (FDA). An FDA committee granted an EUA for the Pfizer vaccine on Dec. 10, and the Moderna vaccine will be reviewed a week later. Our recommendations assume that both EUAs will be granted. In order for an EUA to be granted, the data submitted is rigorously reviewed by teams of FDA scientists.

What insights can you provide on any potential vaccine side effects for various populations—including the elderly and younger children?
We currently only have safety data from the short-term duration of the study trial. This means that we don’t know all of the potential side effects of the vaccine, particularly long-term side effects. We do know that the following have been reported as possible side effects which can last up to a week after receiving the vaccine:

• Pain and redness at the injection site
• Feeling tired and run down a day after receiving the vaccine
• Headache, muscle aches, chills, joint pains, or fever
• Possible allergic reaction in individuals with known allergies

At this time, vaccine trials including children, or pregnant or breastfeeding women have not been completed. Vaccines can affect children differently than adults, so further testing will be necessary to make sure any coronavirus vaccine is safe for children.

handful of recently vaccinated people in the United Kingdom have reported an allergic reaction after receiving the initial injection. This isn’t unusual. However, if you’re prone to severe allergic reactions from vaccines or injections, you should first consult with your physician before getting vaccinated

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