Covid vaccine reaction: What is an anaphylactoid reaction? Can the vaccine cause one?

According to the World Allergy Organisation, anaphylaxis is an “acute, potentially lethal, multi-system syndrome”.

Both anaphylactic and anaphylactoid reactions emerge as the result of an “overreactive and misdirected immune response to a substance (antigen) that is viewed by the body as foreign”.

But anaphylactic reactions take place only following previous exposure to an offending agent.

Anaphylactoid reactions, on the other hand, occur when the body responds to an antigen for the first time.