If I have allergies, should I be worried about the COVID-19 vaccine?

UIHC expert answers this and more questions about vaccine side effects

Pharmacy technician Suzanne Eagan shakes a vial of the Pfizer-BioNTech COVID-19 vaccine before drawing a dose for a heal
Pharmacy technician Suzanne Eagan shakes a vial of the Pfizer-BioNTech COVID-19 vaccine before drawing a dose for a health care worker at the University of Iowa Hospitals and Clinics in Iowa City on Monday, Dec. 14, 2020. (Andy Abeyta/The Gazette)

As rollout of vaccines is underway in Iowa and across the country, public health officials are closely watching for any adverse reactions or unusual side effects from the COVID-19 vaccines.

It’s typical to experience a sore arm or a slight fever after receiving a vaccine. That’s just your immune system kicking in and learning how to fight off the virus.

There have been some instances of people with a certain medical history going into anaphylactic shock, a life-threatening allergic reaction after receiving their shot.

As the vaccine reaches more Americans, officials are finding these kinds of extreme reactions are extremely rare. But this has still left some wondering about their own risk, according to questions from readers sent to The Gazette.

» Getting vaccinated: Do you qualify for the vaccine in Iowa? Check our chart to find out

The Gazette asked Dr. Pat Winokur to help answer these questions. Winokur is an infectious disease specialist and University of Iowa College of Medicine executive dean. She’s also the principal investigator on the UI portion of the clinical trial for the vaccine developed by Pfizer and BioNTech.

If I have an allergy, should I be worried about a reaction from the COVID vaccine?

Those who have had allergic reactions to things such as food, latex, pollen and bee stings should still get the COVID-19 vaccine, Winokur said. Even those who have allergies to penicillin, antibiotics or types of medications are not at risk if they get a COVID-19 vaccine.

However, Winokur said people who have had an anaphylactic reaction to any type of vaccine should not receive this shot.


The Centers for Disease Control and Prevention has issued guidelines for those who have experienced allergic reactions to injectable medications — namely polyethylene glycol, which is an ingredient in both COVID-19 vaccines. These individuals should not get a COVID-19 vaccine.

Winokur said data shows if someone were to have a negative reaction to the vaccine, it would happen within 15 minutes after the dose is injected — which is why providers make people wait 15 minutes after receiving the shot.

For those who have a strong medical history of allergic reactions, Winokur said some providers may opt to extend that watch period to 30 minutes.

“This is where there’s a judgment call,” Winokur said. “Some of our patients that have strong allergy histories are a little more nervous and they want to be sure, so that’s where we take a little bit of extra precaution.”

» More questions answered: Who’s eligible? Can I sign up? Where can I get the vaccine? And more info for Iowans

Should I get a vaccine if I’m immunocompromised?

Federal officials say people who have an impaired immune system, including those on immunosuppressant medication, can still receive the vaccine.

The vaccine is just as safe for people who are immunocompromised as it is for others, but the efficacy might be lower, Winokur said.

“But we do recommend they get vaccinated,” she said.

If I miss the second dose, is the vaccine still effective?

Both COVID-19 vaccines available are a two-dose series, but what if someone misses that second shot?

The first dose is somewhere between 50 percent to 80 percent effective in preventing COVID-19 illness, but it’s only after that second shot that it reaches 95 percent effectiveness rate.

People who only have one shot should still have some level of protection against severe infection, Winokur said. However, since researchers only studied patients who received both doses, it’s unclear how long one shot would be effective.

Winokur said its key anyone who missed their second dose seek it out as soon as possible. She believes individuals will still develop a strong immune response to the virus, even if the second shot is delayed.

Do we know how long this vaccine will be effective?

At this time, scientists aren’t certain how long immunity from the vaccine lasts.

Participants in vaccine clinical trials will continue to be monitored for two years, and researchers are collecting information on patients’ antibodies and whether anyone develops COVID-19 symptoms.

Until that data is analyzed, it’s unclear whether vaccinated people will need a booster shot or even a new COVID-19 shot every year.

Will the current vaccines be effective against the new COVID-19 variants?

Late last year, a mutation of novel coronavirus was discovered in other parts of the world, including the United Kingdom. While it’s common for viruses to mutate, experts have found the newest variant is more contagious that its predecessors.

So far, data scientists have suggested that the COVID-19 vaccine is effective against various mutations of the virus, Winokur said.

“The nice thing about the vaccine is you develop antibodies to different portions of the spike protein and those mutations are very specific, so you might affect the antibody that’s from the area where the mutation occurs,” Winokur said.

Does the COVID-19 vaccine cause sterilization?

No, it does not. Scientists, doctors and public health officials nationwide agree that infertility is not a side effect of the COVID-19 vaccine.

Concerns about the vaccine have morphed into a slew of speculative social media posts that have spread misinformation about potential side effects.

That fear seems to tie back to one anonymous source that claimed the vaccine’s gene sequencing contains a spike protein that overlaps with a protein found in the placenta, which develops during pregnancy. According to the social media post, the vaccine forms an immune response against the spike protein needed for the placenta.

The data behind that claim was false, Winokur said.


“The sequence was not long enough to actually trigger an antibody response,” she said. “You really have to have a certain size of a protein to allow an antibody to develop, and that sequence wasn’t long enough.”

The spike protein in the vaccine is the same protein found in the novel coronavirus, meaning experts can study for any adverse reactions in pregnant women who have become infected with the virus. So far, there’s no evidence the virus jeopardizes the pregnancies or causes any side effects in babies.

“We know pregnant women are more likely to have severe COVID illness, but that’s really their lungs and their body’s response, not the pregnancy per say,” Winokur said.

At the current rate of rollout, how long will it take before Iowa reaches herd immunity against COVID-19?

About 75 percent of the population needs to be vaccinated it can reach herd immunity. Based on the state’s current rollout, Winokur believes it will be summer or fall before Iowa reaches that immunity.

New vaccines, in addition to the ones developed by Pfizer and Moderna, will likely be considered in the near future by federal officials. These include shots developed by Johnson & Johnson and AstraZeneca.

The University of Iowa Hospitals and Clinics is also participating in a clinical trial for a new vaccine developed by Novavax.

Winokur said the trial still is in the midst of recruiting 30,000 participants, and researchers will need to wait at least a month after half of the participants have received the second dose before seeking federal emergency use authorization. She estimated it will be at least until March until that occurs.

When asked whether Iowans outside of Iowa City could participate in the clinical trial, UIHC officials said they “do not have the infrastructure and manpower to send our team to distant locations at this time.”

“All personnel working on the study have to be specifically trained for performing clinical research in general and have to be trained for this particular protocol,” officials said in a statement. “What often isn’t obvious is that we have a large team of individuals working behind the scenes for every single study visit, and these visits will be ongoing for two years.”

Comments: (319) 398-8469;

Support our coverage

Our most important Coronavirus coverage is free to the public.

If you believe local news is essential, especially during this crisis, please subscribe. Your subscription will support news resources to cover the impact of the pandemic on our local communities.

Support our coverage

Our most important Coronavirus coverage is free to the public.

If you believe local news is essential, especially during this crisis, please subscribe. Your subscription will support news resources to cover the impact of the pandemic on our local communities.