MURRAY, Utah - The Salt Lake County Health Department is warning parents and staff at a Murray school about the continued increase of pertussis cases, or whooping cough.
Health officials said "transmission is school-wide" at this point, at the American International School of Utah.
School officials told Fox 13 News they are having trouble containing the outbreak because of the high percentage of students who are exempt from vaccinations.
School officials said 11 percent of the students opted for the exemption and chose not to be vaccinated.
The health department recommends no more than 5 percent of students are exempt from vaccinations, otherwise there is no "herd immunity."
That puts a large number of students at risk.