An infectious disease expert explains facts of COVID-19 vaccine

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Wednesday, June 9, 2021 ~ Updated 8:50 AM

Pfizer-BioTech vaccine viles sit on a table before being put into syringes during a Broadway Pharmacy vacation clinic at the Show Me Center in Cape Girardeau on Thursday, March 4, 2021.
Sarah Yenesel

All of the COVID-19 vaccines currently available are safe and effective. This has been verified by the FDA, the CDC and numerous doctors, researchers and medical professionals. They've gone through a rigorous testing and clinical trial phase using a wide cross section of participants. Any assertions these vaccines can give you COVID-19 or cause cancer or lead to autoimmune diseases are completely unfounded. So, if you're thinking of getting the COVID-19 vaccine, you can do so with confidence. That being said, like any other vaccine, medicine or treatment, there are some common side effects. While these observed side effects have been mild to moderate (and are actually a sign that the vaccine is working as intended), it's important to be aware of them so you can continue making the best possible medical decisions for yourself. Here are some of the possible side effects from the COVID-19 vaccine:

Low-grade fever

These fevers range from around 99.5 degrees to 100.3 degrees, slightly higher than your normal body temperature, but not to the point that you should be concerned. While relatively harmless, if you are feeling uncomfortable, things that should help include rest, fluids and a cool, damp washcloth on your forehead or the back of your neck.

Arm tenderness at injection site

It's very normal to feel some pain and soreness at or near your injection site. Again, a cool, wet washcloth on the affected area can alleviate some of this soreness, but you may also find that some stretching or exercising your arm can provide relief.

Dr. William W. Sistrunk, MD, is an infectious disease specialist.


A bit of a no brainer, but if you're feeling chills, an easy way to combat that is by warming yourself with blankets, heavier clothing or a heating pad, and getting rest. Body chills can either be constant or come and go in short periods, but overall, do not last very long.


Headaches are another common side effect. They can come in a number of different varieties and have a number of different treatments, most based on whatever makes you feel the best. Dimming the lights, using a cold pack or hot compress on your head, rest, hydration, rubbing or massaging the affected area, any of these might do the trick. You can also take an over-the-counter medication, but it's not recommended to take pain relievers before you get the COVID-19 vaccine because we don't yet know how they may impact the effectiveness of the COVID-19 vaccines.


An uneasy stomach never feels great, but any uneasiness should both be relatively mild and short lived. Again, the treatment is mostly just doing what feels good for you, whether that be sitting, laying down or drinking water. Over-the-counter options work well, too.


A number of vaccine recipients have mentioned feeling fatigue after getting their vaccines. For the two-shot Pfizer and Moderna vaccines, we've heard people say that neither, either or both shots have caused them to feel tiredness. Most cases of this seem to last about a day, possibly a little more, and rest is the recommended treatment.

Again, these are all relatively minor side effects we see with almost any vaccination, and very few instances of these side effects will require a call to your doctor. If you find that any redness or tenderness gets worse 24 hours after receiving your vaccination or if any of the above symptoms continue to persist after a few days' time, then it would be advisable to contact your health care provider.

Allergic Reactions

Allergic reactions are extremely rare, but can happen, so as a precaution you will be asked to stay for about 15 minutes of observation after receiving your vaccination.

I've had friends and family members who participated in the COVID-19 vaccine trials and others who received the vaccine in recent months, and while some did report mild side effects, they all told me these effects were both temporary and short-lived. You should not expect any of these side effects to last more than a couple days. When I've asked them if they would get the vaccine again, knowing the side effects they experienced, all emphatically said, "Yes."

An informed decision is a better decision. I hope this information is helpful and provides some clarity about the COVID-19 vaccine. If you have more questions about the vaccine or the vaccination process and want to learn more, visit

Dr. William W. Sistrunk, MD, is an infectious disease specialist.