Five confirmed cases of Palo Alto High School students contracting whooping cough (pertussis) has led the Santa Clara County Health Department to schedule a vaccination clinic at the school Wednesday.

A parent or guardian must sign a consent form for students to be inoculated. Parents have been notified of the vaccination clinic.

The county is holding the vaccination clinic because a new vaccine, Tdap, shows great promise in limiting whooping cough outbreaks, according to Dr. Marty Fenstersheib, a Santa Clara County health officer.

Whooping cough outbreaks are persistent and usually fade on their own after a while, Fenstersheib said. "Boosting the vaccine should get it under control sooner," he added.

Whooping cough is a highly infectious respiratory disease that causes severe coughing spells, vomiting and disturbed sleep. Infants are inoculated but that begins to fade by age 12 or 13, Fenstersheib said. It also often goes undetected unless family physicians test for it, he added.

The health department sent out an alert to more than 5,000 physicians, nurses and clinic directors in recent weeks warning them of the pertussis outbreak.

The Tdap vaccine became available in 2005. It also protects against tetanus (lockjaw) and diphtheria.

— Don Kazak