BACKGROUND:
Following widespread varicella vaccination the number and size of outbreaks, defined as >5 cases within 21 days, has decreased. The overall number of varicella cases has dropped significantly while the proportion of cases that are among vaccinated individuals has increased. Varicella occurring in vaccinated individuals is still infectious, typically mild, and therefore harder to diagnose. During the 2003-2004 school year (SY) Philadelphia's varicella entry regulation included childcare, Kindergarten through 3rd, and 6th through 8th grades. VZV (varicella or zoster) is reportable in Philadelphia.

OBJECTIVE:
To describe Philadelphia's school and childcare VZV OPCP and summarize outbreaks for the 2003-2004 SY.

METHOD:
When a VZV report occurs, a phone interview measures compliance with the OPCP. OPCP, initiated in the 2001-2002 SY, includes immediately excluding the case regardless of vaccine status, any immunocompromised or regulation non-compliant children, and distributing an exposure notification letter. Other susceptibles (e.g. exemptions, provisional status, unvaccinated ages 12-18 months) who are exposed (>4 hrs in vicinity/room) are excluded days 8-21 from exposure date or until vaccinated. Prompt reporting allows up to 8 days for vaccination before being excluded. Once an outbreak occurs then all exposed susceptibles are excluded. Additional exclusions (e.g. classrooms without a case) determined by circumstances and outbreak severity.

RESULT:
There were 266 index VZV reports associated with a Philadelphia daycare or school from Fall 2003 through Summer 2004. Most (178/266, 66.9%) reported only one VZV case, and most distributed outbreak notification letters (201/266, 75.6%). Some sites (51/266, 19.2%) excluded children who had been allowed in school without proof of immunity despite the regulation. Only a few (11/51, 21.6%) reported any additional case(s). Twelve (12/266) sites experienced outbreaks (Median 8 cases). Two sites (2/12) implemented quarantine/exclusion policies for exposed susceptible attendees not covered

CONCLUSION:
Enforced entry regulations and OPCP may help decrease outbreaks.

LEARNING OBJECTIVES:
To understand varicella OPCP.