Health departments in New York, Pennsylvania, Illinois, Minnesota, Texas, Arizona, and Colorado are reporting hundreds of cases. Wisconsin and Washington have more than one thousand each.
"They are seeing rates of disease that are higher than what they've seen in close to 50 years," said Stacey Martin of the CDC.
Whooping cough is a highly contagious bacterial infection that triggers violent, uncontrollable coughing, Making it hard to breathe. The disease usually affects young children who haven't completed their full course of vaccinations, and teens and adults who lose immunity as they get older.
California had a severe outbreak in 2010, but thanks to increased awareness and vaccinations, there were no deaths here last year.
Martin said, "It's really important for all adolescents and adults to get their Tdap booster. Also, we're urging for pregnant women to get vaccinated. It's the best way to protect these infants that are really at high risk of disease and also death.
Seattle mom Heidi Bruch did not get a booster shot . She caught whooping cough and gave it her two week old daughter Caroline.
Mother Heidi Bruch said, "My heart just sank. Oh my gosh, I had inadvertently given my newborn a potentially fatal disease. It was a horrible feeling."
They both recovered. For Heidi, it's now a no brainer, she says getting the vaccine is the best way to protect you and your family.
The CDC recommends expecting moms get a booster shot later in pregnancy, that way the mother can pass on antibodies that protect newborns who are too young to be vaccinated.