The whooping cough (or whooping cough) outbreaks ravaging Europe, Asia and parts of the United States are a reminder of the need to get vaccinated, experts say.
Since January, whooping cough cases have risen dramatically in the UK and the rest of Europe, the biggest rise since 2012. China recorded more than 15,000 in January, 15 times more than the same month last year. And small outbreaks have been reported among high school students in the San Francisco Bay Area and several isolated cases in Hawaii. From October to the beginning of the year, New York City suffered an outbreak with more than 200 cases, mostly among young children.
What is happening?
Whooping cough, or Bordetella pertussis —as the bacteria that causes the disease is called—is a highly contagious respiratory condition that spreads through small respiratory droplets. Thanks to widespread vaccination, it is controlled in the US, but there are specific cases, which are usually mild, in vaccinated people.
“Some health departments have informed us of local outbreaks, which we expect to see every year,” said Jasmine Reed, spokesperson for the Centers for Disease Control and Prevention (CDC). “We are not seeing anything unusual.” .
Whooping cough cases in the US in 2024 remain lower than pre-coronavirus pandemic levels: typically about 20,000 a year. In 2012, however, there was an outbreak with almost 50,000, according to CDC data.
Annual cases dropped sharply in the first two years of the pandemic, down to 6,100 in 2020 and just 2,100 a year later. Masking and physical distancing disrupted the normal cycles of many respiratory illnesses, including the common cold, RSV, and flu.
“The coronavirus pandemic may have disrupted the normal pertussis cycle because people weren't getting vaccinated on time and families weren't seeing their doctors as often as we'd like,” said Thomas Murray, a professor of pediatric infectious diseases at the School of Medicine. Yale Medicine.
Warning signs for babies
Whooping cough causes coughing fits that make breathing difficult.
“When it finally stops, you take a breath and it sounds like a whoop”explains William Schaffner, professor of infectious diseases at Vanderbilt University School of Medicine.
In adults and children it can look a lot like a cold, with a runny nose and cough. But in young babies, the infection can be much more serious.
Whooping cough inflames the bronchi or airways of babies, making it difficult for them to breathe. The most common complication of the infection is pneumonia, which can be fatal. According to the CDC, there were 307 deaths from whooping cough between 2000 and 2017. Nearly 85% were babies under 2 months old.
“It's called whooping cough but very small babies don't always cough, they stop breathing,” said Murray, adding that the first thing parents should keep in mind is that anyone who is sick should try to come visit their newborn. “For babies themselves, any fever above 100.4 degrees Fahrenheit is something their pediatrician should know about,” she adds.
If a baby's lips turn blue or he doesn't seem to be breathing as he normally would, that “is something to worry about, especially if he's been around someone who is sick.”
The CDC recommends that babies start the DTaP vaccine series—which prevents diphtheria, tetanus, and pertussis—starting at 2 months. The series includes four more vaccines, at 4 and 6 months, from 15 to 18 months and from 4 to 6 years.
“The concern is that during the COVID-19 period, many children were not vaccinated regularly,” adds Schaffner, and “now professionals are trying to catch up.”
The DTPa vaccine, formulated to provoke an immune response in babies, whose systems are less developed than those of children, is 98% effective in preventing whooping cough during the first year after a five-dose series, according to the CDC. .
Adolescents and adults may require reinforcement
The Tdap vaccine is recommended for children 11 years and older who have not received the DTaP series, or for adults who may need a booster.
“It is important that all adults have received a dose of Tdap. After that, they should get a Td or Tdap vaccine every 10 years,” the CDC's Reed added, noting that protection wanes over time.
Vaccinating adults protects children from whooping cough and reduces illness if the vaccinated person becomes ill. But “compliance with this rule is not optimal, giving older people the opportunity to contract it,” Schaffner said.
Although whooping cough can be dangerous for older adults, the main concern is that an adult will transmit the bacteria to an unvaccinated newborn.
“Anyone coming to see the newborn should have recently been vaccinated with the Tdap vaccine, to provide extra protection around the baby,” Schaffner added.
The CDC advises women to get a booster shot with each pregnancy. The American College of Obstetricians and Gynecologists recommends pregnant mothers get the Tdap vaccine during the third trimester. According to the CDC, this vaccine prevents about 78% of whooping cough cases and 90% of hospitalizations in babies under 2 months.
Is the bacteria mutating?
In 2019, CDC researchers found that the bacteria that causes whooping cough have changed over time, which could make current vaccines less protective than before.
“It is unclear what effect, if any, these changes have on the effectiveness of the vaccine,” Reed explained.
Schaffner said vaccines continue to offer significant protection and are currently the best method of protection.
“It's not like the flu. It mutates very slowly and these strains are sufficiently related to each other, so the vaccine still works,” she stated.
The flu virus mutates quickly, as does the coronavirus, so vaccines against these diseases must be updated every year. The DTPa and Tdap vaccines are not reformulated.
The current outbreaks are not cause for alarm, but parents of newborns should know the best ways to protect their children.
“It will not become a pandemic because we have a highly vaccinated population,” Schaffner said. “However, let's make sure that pregnant women get vaccinated, that babies get vaccinated on schedule, and that the rest of us get vaccinated against Tdap every 10 years.”
