Whooping cough cases in mid-October were more than five times higher compared to the same time last year, the CDC warned Oct. 31.
Here are four things to know:
1. Pertussis cases have been low since the start of the COVID-19 pandemic, but this year's reported cases — which number about 20,000 — are similar to pre-pandemic levels.
2. The CDC expects an increase in whooping cough cases among both vaccinated and unvaccinated populations as typical infection patterns return.
3. The number of infections is likely underestimated, as diagnostic tests are more reliable in the early stages of the illness.
4. Two factors may be contributing to the rise in cases: a pandemic-related decrease in pertussis vaccination rates and the waning effectiveness of the vaccine.