The Isle of Wight Health Department on Friday held a vaccination clinic for the staff of Isle of Wight Academy after two students were found to have pertussis this week.

The on-site clinic administered the Tdap vaccine at no cost to 47 staff members, including teachers, teacher aides, kitchen staff and administrators.

The Tdap vaccine immunizes against diphtheria and tetanus as well as pertussis, also known as whooping cough. The students returned to school after being treated with antibiotics, Headmaster Benjamin Vaughan said this week.

Both elementary students had been vaccinated, which is required by law, yet still contracted the highly contagious bacterial disease that causes violent coughing, he added.

One case was diagnosed last week and the other on Monday.

Pertussis is one of the childhood illnesses that all children are vaccinated against when they are babies and again before they enter school. A completed immunization schedule has long been thought to fully protect against contracting the disease later, but increasing numbers indicate that immunity lessens over time and vaccinated individuals may still contract the disease as an adolescent, older teenager or adult.

For every adult with symptoms of pertussis, there are five adults who show no symptoms. Most infants younger than 1 year contract the disease from an adult. That is why Tdap boosters are especially important for adults and older children, particularly those who have contact with infants.

Local health departments offer the Tdap booster. For more information, call 514-4700 for the Suffolk health department or 357-4177 for the Isle of Wight County health department.