2021 began with hope. The European Union officially permited Biontech/Pfizer's Covid-19 vaccine for usage. Weeks before this decision the Covid-19 vaccine developed by Biontech/Pfizer and another one by Moderna were already distributed in the UK, United States of America and other countries. However, although the vaccines were approved by healthcare regulatory agencies some cases of severe allergic reaction produced suspicion about the vaccine's safety.

Among the 271,000 people who had received the Biontech/Pfizer and Moderna vaccine since mid-December, six patients suffered an anaphylactic shock. Such news about allergic reactions created anxiety. People with allergies might hesitate to get vaccinated. Furthermore severe side effects always nurtures scepticism to vaccines. Now the science community debates about what might have caused anaphylactic reactions. A study co-authored by Natalija Novak from the Department of Dermatology and Allergy from the University Hospital Bonn identifies polyethynele glycol (PEG) as the culprit.

PEG is used in tooth paste and shampoo

PEG is a poyether compound derived from petroleum which has many forms of applications. PEG molecules are used in:

• pharmacy: It is used as excipient and can be found in pills, ointments and injectables
• medicine: bowel cleansing, a lot of laxatives are on the basis of PEG
• nutrition: food supplement products contain PEG, it can be recognized at the number E1521
• cosmetics: PEG can be found in shampoo, tooth paste, lip sticks, cremes, oils etc. PEG works as an surfactant, it is responsible for the foam in the shampoo or tooth paste
• Chemistry: polyethynele glycol is used by archeologists to preserve objects. It has been used to preserve the warship Vasa (built in 1626) or the colors of the famous Chinese terracota army

PEG derivates are seen as environmentally problematic. PEG molecules aren't biodegradable. After every shower or every tooth cleansing little PEG molecules slip through the sewage and can end up in rivers, ground water, lakes and subsequently in the food chain of fishes and other animals.

What do scientists say?

Among some dermatologists PEG is contested. Some scientists believe PEG derivates can cause allergic reactions like skin irritations. If PEG is ultimately responsible for an allergic reaction from Biontech/Pfizer and Moderna Covid-19 vaccine, scientists are not entirely sure but they believe it is possible:

For patients testing positive, avoidance of PEG as well as PEG analogues is strictly recommended. Although the trigger of the adverse allergic reactions suffered by the two NHS workers after receiving the vaccine BNT162b2 against COVID-19 has yet to be determined, the potential role of
the excipient ALC-0159 containing PEG as a high-risk hidden trigger of dangerous allergic reactions should be carefully considered before advising the administration of BNT162b2 vaccine. However, if hypersensitivity reactions to PEG and PEG analogous will be ruled out as a reason for the anaphylactic reactions observed, not all patients with food and drug allergies would have to be advised against BNT162b2 vaccination, but just those allergic to PEG, PEG analogues or other excipients.

The German Paul-Ehrlich-Insitute (Federal Institute for Vaccines and Biomedinices) come to the conclusion that the current Covid-19 vaccines are not generally responsible for severe allergic reactions. However, the institute acknowledges the impact PEG derivates could have:

Experts from the German Federal Institute for Vaccines and Biomedicines, and the European Medicines Agency (EMA) have explored the data in detail and have come to the following conclusions. According to the current data, a generally increased risk of severe adverse effects for persons with previously known allergic diseases cannot be deduced for a vaccination with Comirnaty. Therefore, the European Commission’s marketing authorisation does not impose any contraindication against vaccination in the case of known allergies to food and drugs.

Individuals with a history of a severe adverse reaction related to a vaccine and/or a known severe allergic reaction to an ingredient of Comirnaty were excluded from the pivotal studies. No clinical data on the tolerability (safety) of the vaccine are available for this group of people.

Severe reactions associated with vaccination with Comirnaty have been observed. Possible triggers could be the active substance or excipients. Excipients that could trigger a reaction include lipid nanoparticles containing polyethylene glycol (PEG). They are similar to liposomes, which have been used for many years in pharmaceuticals as carriers for drugs. Pseudoallergic (non-IgE-mediated) reactions to liposomes, which have the clinical appearance of allergic reactions but follow a different mechanism (complement-mediated), are known with other PEG-containing drugs.

In general, Covid-19 vaccines should be safe, also for allergic patients. However, people are advised to consult a doctor who can diagnose a possible contraindication. Also, the German Federal Institute for Vaccines and Biomedicine suggests to observe every vaccinated person for at least 15 minutes. In the unlikely case of a severe allergic reaction appropriate treatment is possible then.