Whooping cough cases surge in US, Europe post-COVID pandemic

There has been a resurgence of whooping cough in multiple countries in 2024, with the US reporting more than 18,500 cases since the beginning of the year.

The number of US cases of the highly contagious infection, also known as pertussis, is nearly five times higher than at this time last year, according to the US Centers for Disease Control and Prevention (CDC).

It also marks the highest caseload at this point of the year since 2014, according to CDC data.

It comes amid a resurgence in Europe as well, with French health authorities reporting the worst epidemic in 25 years.

Public Health France reported last month that there was an ongoing epidemic in the country since early 2024 “with a very significant circulation of the bacteria which has intensified in recent months”.

There have been nearly 35,000 confirmed laboratory cases of whooping cough by PCR test and pertussis has killed 22 children in France this year, including 20 babies under the age of one.

A surveillance system in France put the number of cases seen by general practitioners at more than 130,000, according to the public health agency.

What is pertussis?

While pertussis can start with common cold symptoms, the illness used to be called the “100-day cough,” because it can cause a cough that lasts for weeks.

The illness is particularly dangerous for unvaccinated or partially vaccinated infants. Babies may not cough due to pertussis but rather have difficulty breathing or turn blue.

Experts say the best way to prevent pertussis is through vaccination, and according to the European Centres for Disease Prevention and Control (ECDC), immunisation during pregnancy “is highly effective in preventing disease and death amongst newborns that are still too young to be vaccinated”.

‘Unprecedented resurgence’

There are typically cyclical outbreaks of pertussis every three to five years. The resurgence in the US indicates “a return to more typical trends” after the COVID-19 pandemic,** when pertussis cases fell considerably, the CDC said.

According to France’s Pasteur Institute, the pandemic disrupted the regularity of those cycles. In a report last month, the institute said there had been an “unprecedented resurgence” this year.

The Pasteur Institute scientists hypothesised that this could be due to waning immunity during the COVID-19 pandemic but added that they had sequenced the bacterium’s genome and found proteins in this French outbreak that contribute to the bacterium’s virulence.

They also “identified a bacterial isolate” resistant to first-line antibiotics and said there was a need to closely monitor the bacterial strains responsible for whooping cough.

Rise in cases in early 2024

An ECDC report from earlier this year said there were nearly 60,000 cases of pertussis in European countries during 2023 and up to April 2024, representing a more than tenfold increase compared to 2021 and 2022.

There were more than 13,000 cases of pertussis in England between January and August 2024, according to the UK Health Security Agency (UKHSA), and 10 infant deaths.

Case numbers rose in early 2024, the UKHSA said this month “as expected based on usual seasonal patterns, and fell but remained elevated compared to pre-pandemic years between June and August”.

“Confirmed cases in the second quarter of 2024 were notably high, exceeding those in any quarter of the 2012 outbreak year,” the agency added.