Five students at Lane Tech High School have been diagnosed with whooping cough this year, part of an upward trend nationwide of the respiratory illness, according to the Chicago Department of Public Health.The cases span three grades at the high school, a spokesperson for Chicago Public Schools confirmed to the Sun-Times on Monday. A letter was sent out to the school community following the diagnoses.The school district said the majority of its students are vaccinated against whooping cough, also known as pertussis. Vaccination is required for students at CPS schools, except those with religious exemptions.“The health, safety and well-being of students and staff is a top priority, and that is why Chicago Public Schools continues to work closely with the Chicago Department of Public Health to respond to all communicable and vaccine preventable disease cases,” a spokesperson for CPS said in a statement. “CPS and CDPH are actively monitoring the situation and providing communication to the Lane Tech High School community.” Related Howard Brown to provide $1 million in back pay to laid-off workers as part of settlement A trip to the ER got me to reboot my life -- and take advantage of every moment I’ve got left Rates of whooping cough diagnoses are returning to pre-pandemic levels, with nearly five times the number of cases nationwide since the start of 2024 compared with the same time last year, according to CDC data. Chicago has seen 2.3 times more cases in the same time frame, with the majority of cases in children between 5 and 17, according to the city health agency.“Rates of pertussis have increased both locally and nationwide in 2024 compared to recent years and signal a return to pre-pandemic levels,” a spokesperson for the agency said in a statement. “The single best way to protect yourself and your children from severe pertussis is vaccination.”Symptoms of the respiratory illness often start five to 10 days after exposure, and include difficulty sleeping, struggling to breathe and vomiting and fatigue due to coughing fits, according to the CDC. The illness also causes people to make a “whoop” sound when coughing.The federal health agency also says outbreaks are common in hospitals, day care centers and schools. Children younger than 1 year old, those with compromised immune systems and those with mild to severe asthma are most at risk of the illness, though it can be prevented through vaccines, which the city health agency provides at its vaccine clinics.