Whooping cough, or pertussis, is a respiratory infection that is easily spread from person to person but can be prevented by a vaccine. It can be fatal for young children. The Centers for Disease Control said the number of pertussis cases has grown since a dip during the COVID-19 pandemic. Preliminary data showed that in the first 33 weeks of 2024, there were four times as many cases as the same period in 2023, the CDC reported last month.