Table 1.

Serious adverse events resulting from smallpox vaccination (numbers reflect US epidemiological data from NYCBH-based vaccines) [9,52,74,86,88–92].

Serious adverse event	Frequency after primary (P) or revaccination (R) (cases/million vaccinees)	Susceptible populations	Treatment	Mortality rate	Notes
Generalized vaccinia	P: 23.4–241.5 R: 0.4–42.1	Immunocompromised	VIG in rare immunosuppressed cases	Low
Eczema vaccinatum	P: 8.0–80.5 R: 0.4–5.4	Individuals with atopic dermatitis/eczema	Hospitalization and VIG	High	Can be caused by primary vaccinee with active lesions coming in contact with susceptible person.
Progressive vaccinia (Vaccinia necrosum)	P: 0–2.7 R: 0.3–3.0	Individuals with cell-mediated or humoral immune defects	VIG and antivirals	Very high	Those with cell-mediated defects have worst prognosis.
Postvaccinial encephalitis	P: 1.9–3.4 R: 0–3.0	Most common in infants <12 months. Autoimmunity or allergic reactions to vaccines?	Supportive care	High	Low rate means causality is difficult to prove. Not believed to be result of replicating VACV.
Myo-/pericarditis	P: 4000–5000 R: Unknown	Unknown	Unknown	Low	Effects first noted during the 2003 DOD vaccination campaign.
Death	P: ~2.9 R: ~0				Incidence rate is vaccine strain dependent. Most often due to encephalitis or progressive vaccinia.