The US has seen nearly 28,000 whooping cough cases this year. Here’s what you need to know

By Asuka Koda, CNN (CNN) — For the second year in a row, the US has surpassed 25,000 whooping cough cases — another sign of the risks of falling vaccination levels. Often called the “100-day cough,” whooping cough or pertussis begins with cold-like symptoms such as runny nose, fever or cough that can progress to