The Pennsylvania Department of Health notified the Norwin School District that a student had the highly contagious virus, prompting school officials to pull student immunization records. They said 33 students hadn't had the vaccine and nine had registered for the prom.
But a health department representative said Friday that the district had miscalculated the dates. The nine were contacted Friday morning and told they could attend prom after all.
But the students identified for exclusion still could have a problem with graduation, which falls within the eight- to 21-day after exposure that students are to be excluded from classes and activities.
A student can be readmitted to school if he or she has a blood test proving immunity to chicken pox or received a chicken pox vaccine before or on Sunday, officials said. Administrators are working on a plan to ensure that students who choose to remain excluded will be able to complete requirements for the school year, officials said.
The Department of Health says on its website that parents may opt out of vaccinations for religious or medical reasons, but those students may be barred if there's an outbreak.
