By Michelle Durham

WAYNE, Pa. (CBS) — There has been a confirmed outbreak of whooping cough at a Chester County public school.

Valley Forge Elementary School has had two confirmed cases of pertussis, and that is enough to constitute an “outbreak,” according to Betsy Walls, bureau director for personal health services at the Chester County Health Department.

“All of the kids were protected (vaccinated),” she tells KYW Newsradio, “but that’s because of their age and school requirements. It was the faculty that didn’t have it — in adults it’s not a required vaccine. And so that what was we were doing there on Friday. We thought we would have some students, but we had all adults (needing to be vaccinated).”

One of those diagnosed with the ailment is a student, the other is not.

Health department officials worked with the Tredyffrin/Easttown School District to ensure that everyone is protected against what some people call “the 100-day cough.”

Walls says it’s very important for adults to get that T-DAP vaccine.

“For whatever reason, vaccines we got as children we are waning in our protection as adults,” she notes. “We cough, we go to work, but no one thinks to look for pertussis.”

But now, area physicians are looking for pertussis in patients with a cough lasting longer than a week.

Walls says the T-Dap injection also contains vaccinations against tetanus — valuable protection as the summer months approach — and diphtheria.