On Oct. 28, 2025, The Louisiana Illuminator reported that when there’s an outbreak of a vaccine-preventable disease, state health officials typically take certain steps to alert residents and issue public updates about the growing threat.

That’s standard practice, public health and infectious disease experts told NPR and KFF Health News. The goal is to keep as many other vulnerable people as possible from getting sick and to remind the public about the benefits of vaccinations. But in Louisiana this year, public health officials appeared not to have followed that playbook during the state’s worst whooping cough outbreak in 35 years.

Whooping cough, also called pertussis, is a highly contagious vaccine-preventable disease that’s particularly dangerous for the youngest infants. It can cause vomiting and trouble breathing, and serious infections can lead to pneumonia, seizures and, rarely, death.

Infants are not eligible for their first pertussis vaccine until they’re 2 months old, but they can acquire immunity if their mother was immunized while pregnant. By late January 2025, two babies had died in Louisiana. But the Louisiana Department of Health waited two months to send out a social media post suggesting people talk to their doctors about getting vaccinated. The department took even longer to issue a statewide health alert to physicians, send out a press release or hold a press conference.

Because pertussis vaccine immunity wanes over time, cases can ebb and flow over time. But in September 2024, Louisiana health officials started seeing a “substantial” increase in whooping cough cases, part of a national increase in cases. In late January 2025, physicians inside one Louisiana hospital warned their colleagues that two infants had died in the outbreak. On February 13, the state’s surgeon general, Ralph Abraham, sent a memo to staff ending the general promotion of vaccines and community vaccine events.

As of September 20, Louisiana had counted 387 cases of whooping cough in 2025, according to the Centers for Disease Control and Prevention. The previous 35-year high was 214 cases, in 2013.

Until the September 30 post on X, the Louisiana Department of Health did not appear to put out any public communications about pertussis over the preceding four months, as hospitalizations continued and case levels surpassed the 2013 levels.