Estimated prevalence of smallpox vaccine contraindications in Israeli adolescents.

BACKGROUND

Routine smallpox vaccination for military recruits was discontinued in Israel in 1996. However, Israeli guidelines recommend post-event mass-vaccination. This study aimed to estimate the rate of Israeli adolescents at risk of severe adverse events after vaccination during 1998-2013.

METHODS

The study population included adolescents screened before military service in 1998-2013. Medical parameters correlating with contraindications to smallpox vaccination were retrieved from army databases, and were categorized by severity according to the Israeli post-event strategy.

RESULTS

Of 1,180,964 individuals, 1.86% had vaccination contraindications in a post-event scenario. An additional 1.24% had contraindications in a pre-event scenario. There was an increase in the percentage of contraindications over time, attributed to the rising incidence of atopic-dermatitis.

CONCLUSIONS

Only a small percentage of the adolescent population is ineligible to receive the smallpox vaccine currently in use. This group may be protected by herd-immunity, or by new-generation vaccines designed to prevent severe adverse events.