The second case was not linked or related to the first index case. Interview data indicated that the second case had not been exposed to the first index case. It was a new index case.

As in the first case, the close contacts of the second index case were identified and prophylaxed.

However, was the occurrence of a second case in the same high school an indication to start vaccinating staff and students?

The ACIP (MMWR,February 14, 1997) guidelines for vaccination –available at the time of the outbreak- were not clear cut. The occurrence of three cases within three months in the same setting was considered an indication to start vaccination; however, two cases in three months in same setting may lead to a consideration of vaccination (page 19).

Experts in infectious disease had differing opinions about the decision to vaccinate.

The decision to vaccinate was based on the experiential criterion of an attack rate of > 10 cases per 100,000 people at risk - two cases in a closed community of about 2,500 high school staff and students easily exceeds the > 10 case parameter- and on the expert advice of the CDC and the State Health Department.

The second index case with its fatal outcome provoked anxiety among parents, students and staff and intense media scrutiny.