Whooping cough wave now worst in almost a decade amid back-to-school surge

This year's resurgence of whooping cough cases has now accelerated to the fastest pace on record in nearly a decade, according to figures published Thursday by the Centers for Disease Control and Prevention, as pertussis infections are now again climbing around the country during the back-to-school season.

A total of 291 cases were reported for the week ending on Sept. 14, the CDC says. New York has reported the most cases this week of any state, with 44 infections. Ohio, Pennsylvania and Oklahoma have also reported at least 38 cases each.

This now marks the most infections of the bacteria Bordatella pertussis reported to the CDC in a single week since 2015, when the country was coming off a resurgence of whooping cough cases that had peaked the year before.

Whooping cough disease, caused by the pertussis bacteria, typically starts around a week after people are first exposed to another contagious person. Symptoms can last for weeks to months, typically with the disease's infamous "whooping" as patients struggle to breathe after facing a burst of coughs.

So far this year, 14,569 cases have been reported to the agency, more than four times higher than the number of infections reported by this time last year. 

Cases are also higher than the more than 10,000 cases that were reported by this time in 2019, before COVID-19 pandemic measures also caused plummeting cases of pertussis and other infections that spread through the air.

The need for better whooping cough vaccines

While unvaccinated young children and newborns delivered by unvaccinated moms remain at the highest risk of infection and severe disease from whooping cough, federal health officials have warned for months that the U.S. was likely to see a resurgence of breakthrough infections in older children and adults.

Pertussis cases have largely grown over the past few decades, after the U.S. and other high-income countries switched to pertussis vaccines after the 1970s that triggered fewer side effects but also are less effective at guarding against disease and spread.

Officials in Pennsylvania, which has seen one of the country's largest pertussis outbreaks this year, say that many outbreaks have been fueled by high school students.

"Cases and outbreaks have continued throughout the summer even though most schools were closed," the department said in an alert to doctors in the state this month, urging doctors to prepare for the possibility of a "continued increase" as schools resumed.

In New York, 40% of their cases this year outside of New York City have been in teens ages 15 to 19 years old, according to figures the state's health department shared with CBS News. 

"[W]e are not seeing evidence of a specific cluster or location or event. Cases have been identified all over the state and among children and adolescents in various settings," a spokesperson for the New York State Department of Health said.

In Oklahoma, which has seen one of the steepest increases in cases of any state over recent weeks, cases have been seen in people as old as 86 years old. The median age of cases is 9 years old, the health department said.

"Since Jan. 1, 2024, there have been 162 cases of whooping cough in Oklahoma, which is the highest number of cases since 2017 when 207 cases were reported," Erica Rankin-Riley, a spokesperson for the Oklahoma State Department of Health, told CBS News.

Talks on new trials

The resurgence comes as the Food and Drug Administration is now weighing the prospect of human challenge trials – studies intentionally infecting vaccinated volunteers with the bacteria – in the hopes of accelerating the development of more effective shots to fend off the bacteria.

A panel of the FDA's advisers are scheduled to meet Friday to discuss the trials, which could lead to vetting "new pertussis vaccines for booster vaccination of adults."

The CDC currently recommends a number of pertussis shots for children and adults, including boosters of the Tdap vaccine – which contains antigens designed to protect against pertussis – for all adults every 10 years. 

Around 39% of adults have gotten a pertussis booster in the last 10 years, CDC survey data from 2022 suggests.

Other factors may also be contributing to rising cases, the FDA said, like mutations in circulating pertussis strains and the "rapid waning" of immunity.

The current generation of "acellular pertussis" vaccines are still believed to "provide a significant public health benefit by preventing disease," the FDA said in briefing documents published ahead of the meeting.

"Despite the resurgence of pertussis, current rates of disease are very low relative to the rates reported during the pre-vaccine era," agency officials wrote.