The mRNA-based COVID-19 vaccines, Pfizer-BioNTech/Comirnaty and Moderna/Spikevax, are not recommended for children under the age of 6 months.

Persons with a history of anaphylaxis to mRNA COVID-19 vaccine or its components SHOULD NOT receive the mRNA-based vaccine again. Anaphylaxis is a severe life-threatening reaction with two or more of the following three criteria:

a) Hives or face/eyelid/lip/throat swelling;
b) Difficulty breathing; and
c) Dizziness.

Patients with the following high-risk allergic reactions to a previous dose of mRNA COVID-19 vaccine or its components SHOULD NOT receive the vaccine again:

a) Hives or face/eyelid/lip/throat swelling with onset within 4 hours post-vaccination; and
b) Painful swelling of the inner surfaces of the mouth and/ or large blisters spontaneously occurring at any time after vaccination.

Persons who were diagnosed with myocarditis/pericarditis after a dose of mRNA COVID-19 vaccines SHOULD NOT receive the mRNA vaccines again.

Persons with a history of allergic reactions (including anaphylaxis) to other vaccines can receive the mRNA-based vaccine, unless they have a confirmed allergy specific to PEG (which is a component of the mRNA vaccine).