Scientists may be focused on what has caused severe allergic reactions in at least six people who have received a dose of Pfizer’s COVID vaccine. Both the Pfizer and the Modern vaccine contain small nanoparticles of PEG – polyethylene glycol. The human compound is used as part of the messenger RNA packaging. PEG helps transport the vaccine to human cells and also acts as a boost to our immune response.
Allergic reactions to vaccines are expected to be one in a million doses. But the Pfizer vaccine experienced six such allergic reactions in just 272,000 patients.
Science:
PEG has never been used in an approved vaccine before, but it is found in many medications that have occasionally triggered anaphylaxis, a life-threatening reaction that can cause rashes, stinging blood pressure, shortness of breath and throbbing. fast. Some allergists and immunologists believe that a small number of people previously exposed to PEG may have elevated levels of antibodies to PEG, putting them at risk for anaphylactic reaction to the vaccine.
Others are skeptical about the link. However, the U.S. National Institute of Allergy and Infectious Diseases (NIAID) was concerned enough to convene several meetings last week to discuss allergic reactions with representatives of Pfizer and Moderna, scientists and independent doctors. and the Food and Drug Administration (FDA).
“Until we know there really is a history of PEG, we have to be very careful about talking about it as a deal,” says Alkis Togias, head of allergy, asthma and airway biology at NIAID. . This is very good advice. There can be a variety of reasons for an allergic reaction or perhaps a combination of factors. Anaphylaxis is a serious response of the immune system and there are many factors that could trigger it.
PEG is found in many household products we use every day: toothpaste and shampoo to name two. They are used as thickeners, solvents, fabric softeners and moisture carriers, and have been used as a laxative for decades. But why PEG elicits an immune response is a mystery.
Szebeni says the mechanism behind PEG-conjugated anaphylaxis is relatively unknown because it does not involve immunoglobulin E (IgE), the type of antibody that causes classical allergic reactions. (That’s why he prefers to call them “anaphylactoid” reactions). Instead, PEG triggers two other classes of antibodies, immunoglobulin M (IgM) and immunoglobulin G (IgG), involved in a branch of the body’s innate immunity called the complement system, which Szebeni has been studying for decades. in a pig model he developed.
Why didn’t Pfizer discover the adverse reaction before? Apparently, in establishing its trials, the company excluded people allergic to vaccines in general and allergic to the ingredients found in the serum.
But Pfizer was aware of a potential problem with PEG.
However, companies were aware of the risk. In a stock brochure presented on December 6, 2018, Moderna acknowledged the possibility of “reactions to the PEG of some lipids or PEG associated with NLP”. And in a September paper, BioNTech researchers proposed an alternative to PEG for therapeutic mRNA delivery, noting: “PEGylation of nanoparticles can also have substantial disadvantages in terms of activity and safety.”
Where does this leave millions of people wanting the vaccine? Ultimately, it’s up to the FDA, which can recommend that anyone who gets the vaccine stay close to the office for 30 minutes. An antibody test may also be recommended for those who think they may be allergic to PEG.
Although the number of adverse reactions to the vaccine is still very low, it does nothing for the confidence of the American people, in terms of vaccine safety, to know that some people have problems after receiving the dosage. .