The cacophony of coughs you’ll hear over the next few months will be caused by a mix of respiratory bugs. Some are familiar culprits: the common cold, covid, the flu– and recently respiratory syncytial virus (RSV). But increasingly the cough will be caused by the pertussis bacterial infection.
Called whooping cough because of its most well-known symptom, pertussis can be an unfortunate experience, especially for children who are not strong enough to withstand chest spasms. It can put children in the hospital, although it is rarely fatal. The pertussis vaccine has been part of the routine childhood vaccination schedule for decades, and cases have declined by about 90% since the vaccine era. The incidence of the infection dropped dramatically with the COVID pandemic, but now cases are on the rise again, with more than 16,000 reported in the US this year as of September 28. That’s more than four times the number of reported cases at this time last year.
“The United States is beginning to return to pre-pandemic patterns where we typically report more than 10,000 cases of whooping cough each year,” says a Centers for Disease Control and Prevention spokeswoman.
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Here’s what you need to know about pertussis and how to keep yourself and your family safe from infection.
What is Pertussis?
It is caused by a bacterium called pertussis Bordetella pertussiswhich spreads easily between people through direct contact or through droplets from someone’s mouth or nose. The bacterium settles in the lining of the respiratory system, where it produces and releases toxins. These toxins seem to do the most damage during infection, so getting antibiotics early, before the bacteria have had time to spew out a lot of poison, is key to managing the disease.
But early treatment is difficult because the first stage of pertussis infection is easy to confuse with other respiratory illnesses, says Flor Muñoz, an expert in pediatric infectious diseases at Baylor College of Medicine. “At first you have something that looks like a cold, with congestion, that doesn’t feel right, maybe a sore throat,” he says. In many healthy adults, pertussis can be limited to a persistent cough, while older children may have only non-specific symptoms, such as a runny nose and cough, Muñoz added. “A lot of times, it gets lost,” he says.
Because whooping cough is highly contagious, even those with mild symptoms can spread it to particularly vulnerable groups, such as young children and the elderly, who will develop more severe cases.
When it becomes a serious illness, pertussis causes a violent cough, punctuated by gasping noises caused by forceful breathing. Muñoz says that the coughs between howls are brutal. “They are unstoppable,” he says. “It’s so strong you can actually vomit.”
Very young children are particularly vulnerable because they cannot yet breathe through their mouths, so mucus and intense coughing can prevent them from receiving enough oxygen. In 2023, more than one in five children under six months with pertussis were hospitalized. Treatment often includes intravenous fluids to keep people hydrated, as well as breathing support, Muñoz says.
Even after the whooping cough phase is over, the infection does not take place. During recovery, people are left with a persistent cough that can last for months, which once gave the infection the nickname “100-day cough.” And starting antibiotics at this stage cannot speed up recovery; bacterial toxins are already abundant.
Pertussis case rates
The total of more than 16,000 cases of pertussis reported to the CDC so far this year likely understates the actual number of infections because small ones often go undiagnosed. New York state, Pennsylvania, Illinois and California have had the highest number of reported cases, with more than 1,000 in each state.
Of course, the recent rise in pertussis cases isn’t limited to the U.S. England, for example, saw more than 10,000 cases in the first half of 2024 alone, surpassing the annual total by more than a decade. “These numbers are big, so it’s not just that we had a deficit (in cases), and now we’re paying for that,” says Pejman Rohani, an epidemiology modeler at the University of Georgia. “I think something is going on. I don’t know what that something is.”
This century, the numbers in the US have generally been between 10,000 and 20,000, with occasional worse years, most notably 2012, which saw nearly 50,000 cases. A significant decline began in 2020, with an incidence of more than 2,000 cases in 2021. But with 2024 just a few months away, rates are already in line with a full-year standard before the COVID pandemic.
Pertussis vaccine
The vaccine that initially reduced pertussis rates is no longer used because it contained the whole bacteria and caused rare but serious side effects such as lameness and convulsions. Since the 1990s, the US has used what is called an acellular vaccine, which contains only a few components of the bacteria, such as skin proteins or pertussis toxin. These materials are combined with the tetanus and diphtheria vaccines into two single vaccines: DTaP (used for infants and young children over two months of age) and Tdap (used for older children and adults, and people in the last trimester of pregnancy). ).
Although safer than the whole-cell version, these new vaccines may not provide as strong or long-lasting protection, Rohani says, because they don’t contain enough parts of the bacteria to trigger an immune system response. . It’s hard to fully assess that concern, he says. But Muñoz says that according to estimates, immunity from an infection or vaccine can last about six years. That could open a window for new infections, as the US recommends tetanus boosters, with or without pertussis, only once every 10 years.
In the U.S., vaccination uptake is strongest among children, at 94 percent, and 89 percent among teenagers, according to a CDC spokeswoman. In adults the coverage is less, however. A 2022 CDC survey suggested that about 40 percent of US adults had received a Tdap vaccine or booster in the past 10 years. And only about 55 percent of women who have recently had a baby They received the Tdap vaccine during pregnancyAccording to another survey conducted in early 2023. Doctors recommend that pregnant people get a new dose for each pregnancy. Muñoz points to disrupted access to health care in the early days of COVID and increased vaccine hesitancy as factors in low vaccination rates among adults.
Even if these adults do not suffer from a serious pertussis infection, they are at risk of transmitting the bacteria to weaker children. And the low vaccination rate of pregnant people is even more worrying, says Muñoz. Immunity acquired during pregnancy is the only protection babies have until they are two months old and can start receiving their own vaccines. “It wouldn’t be fair for babies to die from pertussis right now, given the tools we have,” he says, noting that the vaccine works and that health experts have experience getting it under control. “We’ve done it before; we have become too lax.”
