Prospective and retrospective multicenter study to estimate the proportion of patients who tolerated continuation of COVID-19 vaccination (absence of anaphylactic manifestations).

secondly, to determine the proportion of definite anaphylactic reactions in cases of suspected anaphylaxis following administration of a COVID-19 vaccine.

Comprehensive allergological investigations involving clinical, skin and biological tests will enable us to determine whether or not vaccine components, and in particular excipients (PEG2000, PS80 and tromethamine), are responsible for anaphylactic reactions to COVID-19 vaccines.

A biological collection will be set up during this clinical study to study the immunological mechanisms, effector cells and signalling pathways involved in these reactions.

Eligible patients will be identified via the pharmacovigilance centers and allergology hotlines set up in each center, according to the organization specific to each hospital site. .

The patient identified in this way will be contacted by the secretariat of each allergology center to schedule an allergology consultation at least 3 to 5 weeks after the reaction (the usual delay before exploring an anaphylactic reaction to avoid the risk of false negatives). Then, in the framework of a collegial meeting ,the patient's file will be reviewed in order to specify the history of the allergic disease and the modalities of subsequent COVID-19 vaccination.

A follow-up telephonique call at 6months will be made systematically for patients who have continued vaccination to ensure that there are no significant adverse events related to the COVID-19 vaccine.

Inclusion Criteria:

• Age ≥ 18 years
• Anaphylactic reaction to a COVID-19 vaccine administered by Pfizer-BioNtech or Janssen or Vaxzevria or Moderna, at least 3 weeks old at the time of the allergology consultation.

An anaphylactic reaction is defined as the occurrence of any of the following systemic manifestations within a few hours of administration of a COVID-19 vaccine:

• skin rash with urticaria and/or angiodema,
• and/or associated with respiratory signs (dyspnea, bronchospasm, desaturation), and/or digestive disorders (intense abdominal pain, diarrhea, vomiting, nausea), and/or neurological disorders (loss of consciousness, feeling of malaise), and/or hypotension, tachycardia.
• Affiliation to a Social Security system
• Signature of the informed consent
• Stop taking antihistamines at least 3 days before skin allergy tests are performed

Exclusion Criteria:

• Other non-anaphylactic systemic reactions after administration of COVID-19 mRNA vaccine (serum sickness, vasculitis, Guillain-Barré syndrome)
• Pregnancy and lactation
• Disorders of hemostasis or severe bleeding considered a contraindication to intramuscular injection