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Fortunately these anaphylactic reactions are rare but they occur more often than with other vaccines, and are concerning enough for @NIAIDNews to convene several meetings last week with experts, company reps and the @US_FDA, and to start a study. https://bit.ly/3aBFhhV
Much is still unclear, but some scientists think these reactions may be triggered by PEG, a molecule on the particles that ‘package’ the mRNA in the Pfizer and Moderna vaccines. https://bit.ly/3aBFhhV
Similar reactions have been seen with some drugs containing PEG. Some people may be more susceptible because they have high levels of antibodies against PEG, which is also used in shampoo, toothpaste, and countless other products. https://bit.ly/3aBFhhV
The anaphylactic episodes aren't a complete surprise, @Jopdevrieze found. Moderna told investors about possible allergic reactions in a prospectus, and BioNTech scientists published a paper earlier this year about a possible replacement for PEG that they think might be safer.
Key point: Even scientists who believe PEG is the problem say vaccination should continue, as the benefits outweigh the risks. But more data are needed. “These next couple of weeks are going to be extremely important for defining what to do next.” https://bit.ly/3aBFhhV
