The potential side effects of COVID-19 vaccines have increasingly become a topic of discussion, especially since the suspension of the Oxford-AstraZeneca and Johnson and Johnson (J&J) vaccines in many countries over blood clot fears. People with serious medical allergies, in particular, have grown worried about the possible risks, though in these uncertain times it is easy to get worked up over nothing.

While it is true that the current COVID-19 vaccines have been reported to cause strong allergic reactions, it is extremely rare.

In Germany, allergy outpatient clinics are seeing an influx of people extremely worried about the vaccines, says Dr. Ludger Klimek, president of the Medical Association of German Allergologists (AeDA). "Many would like to be vaccinated and are looking forward to it, and then they read that a severe reaction is possible," he remarks. "This has raised a lot of uncertainty."

Since vaccinations started in England and the United States, there have been reports of some strong allergic reactions that occurred shortly after vaccination and had to be treated. Precise data on the frequency of such reactions after COVID-19 vaccinations aren't currently available, however.

Based on existing preliminary data, Klimek says, the new messenger RNA vaccines, also called mRNA vaccines, by Pfizer-BioNTech and Moderna likely carry a somewhat higher risk than the other COVID-19 vaccines, around 2.5 to 4 times higher. Nevertheless, he adds, the risk is still extremely low, namely "one case in every 100,000 vaccinations."

Allergic reactions aren't confined to COVID-19 vaccines, of course, but can occur after taking any medication. No one becomes allergic to a substance by taking a COVID-19 vaccine, says Klimek, explaining that an allergic reaction to an ingredient in the vaccine means you've already been sensitized to it. Since the injected dose of it is higher, the reaction can be stronger.

Not all allergy sufferers are affected equally. "If you have hay fever, you're not really at higher risk of side effects than someone without allergies," Klimek says.

However, if you've ever had an allergic reaction to certain medications, a laxative or X-ray contrast agent, for example, you might also have one to ingredients in the COVID-19 vaccines, says Klimek, noting that known allergenic substances in medications include polyethylene glycol, polysorbate and ethylene oxide.

While completely eliminating risk is near impossible, Klimek says, you'd do well to consult an allergist if you've had an allergic reaction to a medication. If need be, the allergist can refer you to a specialized allergy center that can make a specific recommendation based on your allergy and the ingredients in the various COVID-19 vaccines.

As for whether, say, the Pfizer-BioNTech vaccine would be a better choice than AstraZeneca's or vice versa, Klimek says: "[An assessment like] this is very complex and not affordable by every doctor's surgery."

In any event, health experts, such as those at Germany's Federal Centre for Health Education (BZgA), have made it clear that if you know you're allergic to an ingredient in a COVID-19 vaccine, you shouldn't get that vaccine.

Before you're vaccinated, it's imperative that you accurately and thoroughly fill out your medical history questionnaire, if in doubt, with the help of an allergist, so that personnel at the vaccination provider site know what to watch for and can further evaluate you if necessary.

After getting the jab, you have to remain on site for 15 minutes so that you can be monitored as a precaution. The wait is 30 minutes if you've ever had an allergic reaction to a vaccine, the BZgA says.

The most serious kind of allergic reaction is anaphylaxis, in which your immune system releases a flood of chemicals that can cause you to go into shock. "This is definitely life-threatening," remarks Klimek. Less serious potential reactions include a skin rash, scratchy throat or itching.

According to the BZgA, vaccination provider sites and mobile vaccination teams are required to be equipped to treat any cases of anaphylaxis quickly.