Introduction: The recent US smallpox vaccination (SPV) campaign started in 12/2002. Military and civilian populations report adverse events (AEs) to the Vaccine Adverse Event Reporting System (VAERS). Civilians had a higher crude reporting rate of myopericarditis after SPV than military personnel. Objective: To determine if overall SPV-associated reporting rates are higher in the civilian than military population, after age and sex stratification. Methods: Numerators were SPV reports in VAERS from 12/12/02 to 3/1/04. Underreporting was possible and diagnoses were not necessarily confirmed. Denominators (number of vaccinees) were from the Defense Medical Surveillance System (military) and the Pre-event Vaccination System (civilian), large administrative databases.  

Results:

Subject Gender Age (Years)	Category of Reports	Civ/Mil Rate Ratio	95% LL	95% UL	Category of Reports	Civ/Mil Rate Ratio	95% LL	95% UL
All Female
<35	Serious	13.0	5.8	29.3	NonSerious	13.3	10.6	16.7
35-54	Serious	4.5	2.1	9.3	NonSerious	6.2	4.4	8.7
>54	Serious	0.2	0.1	1.0	NonSerious	3.9	0.5	27.5
All Male
<35	Serious	11.3	5.8	22.1	NonSerious	26.9	21.5	33.7
35-54	Serious	8.2	5.0	13.5	NonSerious	10.0	7.5	13.2
>54	Serious	1.7	0.5	5.7	NonSerious	3.3	1.5	7.3

Reporting rates to VAERS of AEs after SPV were significantly higher in civilian than military personnel aged <55 years. The civilian/military rate ratios decreased with age. Conclusions: Age and sex stratification did not resolve the differences in the military and civilian reporting rates. Reasons for higher civilian reporting rates may include differences in reporting requirements and/or practices, and the healthy “soldier” effect.