Table III.

Presentation of immediate reactions after COVID-19 mRNA vaccines (SVaT assessment)^∗

Anaphylaxis	Acute stress response (ISRR)	Vasovagal reaction (ISRR)	Vocal cord dysfunction
Onset
Rapid (5-120 min)	Before, during, or after vaccination (very rapid, <5 min)		Variable (can be very rapid or delayed)
Symptoms
Skin
Generalized itching; feeling of warmth; hives; swelling (face, extremities, or generalized)	Pale peripheral skin color; sweaty or clammy and cold extremities		None
Oral
Itching or swelling (lips, mouth, tongue)	Dry mouth	None	None
Ocular
Eyes itching or tearing	None		None
Upper respiratory
Nasal itching; congestion; runny nose; sneezing; throat itching, swelling, or tightness; voice change (hoarseness)	Feeling of choking; “globus” sensation (mass or lump in throat); difficulty swallowing	None	Globus sensation; throat tightness or closure; voice change (hoarseness, weak)
Lower respiratory
Shortness of breath; chest tightness; coughing (spells)	Shortness of breath; chest tightness	None	Shortness of breath (predominant); chest tightness; cough
Gastrointestinal
Nausea; vomiting; diarrhea; abdominal cramps	Nausea	Nausea; vomiting (self-limited)	Dysphagia; choking sensation; reflux
Cardiovascular
Dizziness; chest pain; palpitations; syncope (unresponsive to positioning)	Dizziness (lightheadedness); presyncope; palpitations	Dizziness, rapidly followed by transient loss of consciousness	None
Neurological
Apprehension; impending doom; incontinence	Fearfulness; numbness; perioral tingling; spasms of hands and feet; weakness; seizures	±Tonic-clonic seizure	None
Gynecological
Uterine cramps	None	None	None

Signs (observed on examination)
•Flushing (erythema); conjunctival erythema; periorbital edema; urticaria (injection site, localized or generalized); angioedema (localized or generalized) •Laryngeal edema; dysphonia; stridor •Wheezing; reduced air entry; use of accessory muscles; cyanosis •Reduced capillary refill; altered mental status; sudden behavioral change (children, elderly)	•Rapid, deep breathing out of proportion to symptoms •Normal chest and throat examination (hyperventilation) •Anxious appearance •Continued absence of signs of anaphylaxis	•Rapid onset of syncope (increased risk if upright at time of vaccination) •Rapid recovery with supine position ± leg elevation	•Wheezing (stridulous) sounds; however, on auscultation, sounds will localize to neck without chest wheezing •Lack of response to albuterol should prompt suspicion

Vital signs
Tachycardia or dysrythmia Hypotension Hypoxemia Tachypnea	Tachycardia Hypertension or normal blood pressure Tachypnea (hyperventilation) Normal oxygen saturation	Bradycardia (transient) Hypotension (transient) Normal breathing Normal oxygen saturation	Tachypnea Normal heart rate, blood pressure, and oxygen saturation

Biomarker
Acute serum tryptase∗	None available

Treatment
First-line •Epinephrine, can repeat every 5-15 min for maximum 3 doses Supplemental If hypotension: •Supine positioning •Leg elevation •Intravenous fluids If hypoxemia: •Oxygenation •Short-acting beta-agonist inhalation or nebulization Second-line •Can consider second-generation H1 antihistamine for cutaneous features •Can consider corticosteroids for asthma exacerbation, severe cutaneous symptoms, or respiratory symptoms	•Monitor closely •Frequent examination (skin, oral, throat, cardiac, and respiratory) •Repeat vital signs as indicated to ensure recovery before discharge •Reassure and distract with calming strategies •Reduce environmental stimulation to decrease stress •Use behavioral relaxation techniques		•Supportive care and reassurance •Breathing strategies such as panting to facilitate glottic aperture opening •Continuous positive airway pressure ventilation •Refer to otolaryngologist; may require speech therapy for long-term treatment

SVaT, Symptoms, signs, Vital signs and acute Tryptase.

^∗Obtain within 15-180 min of symptom onset.