Table 3.

Incidence of adverse reactions to mRNA/LNP Covid-19 vaccines.

Clinically-based grading*	Symptom types	Brighton Levels**	Female	Male	All***
Grade 0	none	NA	74	67	141 (72 %)
Grade 1 (Mild)	usual vaccine reactions		28	11	39 (20 %)
Grade 2 (Moderate)	hypersensitivity reactions	≥2	7	5	12 (6 %)
Grade 3 (Severe)		1	3	0	3 (2 %)
Total			112	83	195 (100 %)

*Grade 0 is no adverse effect, Grade 1 “usual vaccine symptoms” include fever, arm pain, local redness, weakness, headache, chills, pruritus, depression, abdominal pain, indigestion, bloating, arthralgia, muscle pain, or fatigue. Grade 2 reactions represent allergic symptoms which pass spontaneously with or without epinephrine, antihistamines, or other pharmaceutical interventions. Grade 3 defines anaphylaxis or life-threatening reactions requiring emergency care (resuscitation and/or hospitalization).

**Level of diagnostic certainty for anaphylaxis, as defined in the Brighton Collaboration's anaphylaxis case definition guidelines [41]. According to this system level 1 “true anaphylaxis” is distinguished from other manifestations of allergy by its “diagnostic certainty”, defined by a complex matrix of major and minor criteria. Our Grade 3 reactions roughly correspond to Brighton level 1, i.e., true anaphylaxis, wherein at least a major hemodynamic/circulatory or cardiopulmonary symptom (heart/back/limb pain, hypo- or hypertension, (angio)edema, swelling of the lips, tongue, or face) and a major skin alteration (i.e., flushing, rash, erythema) are concurrently present. Brighton levels ≥ 2 (Grade 2) are defined as all moderate (Grade 2) HSRs that involve non-life-threatening symptoms.

***The % values represent incidence in the 195 participants of this study involving both healthy and allergic people who were recalled for blood donation because of his/her HSR.