Table 1. Serious adverse events resulting from smallpox vaccination (numbers reflect U.S. epidemiological data from NYCBH-based vaccines) [9,52,77,90,99,101-104].

Serious adverse event	Frequency after primary (P) or re-vaccination (R)(cases/million vaccinees)	Susceptible populations	Treatment	Mortality rate	Notes
Generalized vaccinia	P: 23.4 – 241.5 R: 0.4-42.1	Immuno-compromised	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.
Post-Vaccinial 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: 4,000-5,000 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