Whooping cough is spreading at a California school, infecting several as health officials warn of the dangerous disease.

The Pasadena Public Health Department announced Wednesday that there are four confirmed cases of whooping cough at Don Benito Fundamental School in the Pasadena Unified School District.

Vaccinated children and adults have a much lower chance of infection, health officials said. Children usually receive a Diphtheria, Tetanus, and Pertussis (DTaP) vaccine. A health official told ABC 7 that children are the “perfect vessel” for transmission.

“Kids are the perfect vessels for transmission – even if they’re fully vaccinated. In this instance, all four of our cases were fully vaccinated,” Dr. Matt Feaster told ABC 7. “What the vaccine does is protect you from severe illness and death.”

PPHD said they are working with the elementary school to monitor for additional cases.

“Guidance has been provided to all identified close contacts, including instructions for testing, treatment, and home isolation if symptoms appear,” they said.

Pertussis symptoms usually appear 5 to 21 days after exposure, the health department said. Pertussis is an ancient disease that was first described in the 16th century and causes symptoms like a cold along with its trademark severe coughing fits.

Health officials are advising anyone exposed to the disease to:

• Monitor for symptoms for 21 days, especially in children.
• Watch for worsening cough or breathing difficulties.
• Contact your healthcare provider if symptoms develop.
• Keep sick individuals home until cleared by a provider or after 5 days of appropriate antibiotics.
• Prevent contact between sick individuals and infants or pregnant people.
• High‑risk contacts, including infants under 1-year, pregnant people, and caregivers of infants, may need preventive antibiotics even without symptoms.

Parents told ABC7 that they’re concerned about the outbreak, but have some confidence it can be handled.

“They’re handling it, pretty much to the best of their ability,” parent Mani Grundy said.. “They sent full notice to all families so they’re doing the best that they can.”

“I’m a little scared… I don’t know. I kind of feel safe, but I don’t know,” Patriciea Charles added.