Nationwide digital surveillance reveals resurgence of Pertussis through real-time decision support systems

For decades, the world has relied on vaccines to keep whooping cough, a severe respiratory infection, at bay. In wealthy nations, the disease became a rare visitor, appearing only in small, predictable waves every few years. This stability was so reliable that when the global pandemic of 2020 arrived, the usual patterns of disease vanished. Lockdowns and mask-wearing, intended to stop a different virus, accidentally silenced the circulation of whooping cough as well, creating a quiet period that lasted for several years. However, as the world opened up again, health officials began to worry that this silence might have been deceptive. They feared that the virus had not disappeared but was simply waiting, and that once people stopped wearing masks and gathered in groups again, the disease could return with unexpected force. The question facing public health experts was not just whether the virus would come back, but how quickly they could see it returning and who would be most at risk.

To answer this, a team of researchers in France turned to an unexpected source of information: a digital tool used daily by general practitioners. This tool, known as a computerized decision support system, helps doctors choose the right antibiotics for their patients. It is not a laboratory test that confirms a disease, but rather a record of what doctors are thinking about when they treat a patient. When a doctor suspects a patient has whooping cough, they often consult this system to confirm the diagnosis and find the correct treatment. By tracking millions of these digital requests over seven years, the researchers could see the pulse of the disease in real time, long before official government reports were compiled.

The data revealed a dramatic story. Between 2018 and 2023, the number of doctors asking about whooping cough remained low and steady, hovering around one request per 100,000 people each week. Then, in the spring of 2024, the numbers began to climb. The researchers watched as the weekly requests jumped from less than one to nearly 20 per 100,000 people. This surge was not a slow build; it was a rapid explosion that peaked in the summer of 2024. The digital system detected this rise nearly four weeks before the French Ministry of Health issued its first official alert. By the time the government sounded the alarm, the digital records had already shown that the disease had reached its highest point, with thousands of doctors across the country seeking advice on treating the infection every single week.

The researchers broke down the data to see who was suffering the most. They found that children under the age of 15 were hit the hardest. While the risk for adults increased significantly, the risk for children was far more severe, with the number of requests for them rising to more than 15 times the levels seen in previous years. Pregnant women also faced a sharp increase in risk, though not as extreme as that of children. The data showed that the disease did not just affect one group; it swept through the entire population, but the impact was uneven, leaving the youngest members of society most vulnerable.

To understand the sheer scale of this return, the team used a statistical model to predict what the number of cases should have been if the disease had continued its normal, quiet pattern. The difference between what they predicted and what actually happened was staggering. The model estimated that there were over 1,300 percent more requests for whooping cough treatment in 2024 than would have been expected. This was not a minor fluctuation; it was a massive resurgence that dwarfed the small, predictable waves of the past. The researchers calculated that the number of people seeking treatment was nearly nine times higher in 2024 than it had been in the years before the pandemic.

The study also mapped the disease across the country, revealing that the return of whooping cough was not uniform. Some regions were hit much harder than others, creating distinct clusters of infection. The western coast of France, particularly areas like Brittany, became the epicenter of the outbreak, with the disease spreading from the coast inland. Interestingly, the areas that were hit the hardest were not necessarily the places with the lowest vaccination rates. Many of these regions had high vaccination coverage, with most children and pregnant women already protected. This finding challenged the simple idea that the outbreak was caused solely by people skipping their shots. Instead, it suggested that the bacteria itself might have changed, becoming more capable of spreading even among vaccinated people, or that the virus had evolved in ways that allowed it to bypass the protection vaccines usually provide.

As the year 2024 turned into 2025, the intensity of the outbreak began to fade, but the digital records showed that the disease had not returned to its pre-pandemic silence. The number of requests remained higher than before, suggesting that the virus had found a new, more permanent place in the population. The researchers concluded that this digital surveillance method provided a powerful new way to watch for disease. By listening to the questions doctors asked in real time, health officials could see the shape of an epidemic as it formed, identifying the most vulnerable groups and the hardest-hit regions long before traditional methods could catch up. The study confirmed that whooping cough had returned with a vengeance, driven by complex factors that went beyond simple vaccination gaps, and highlighted the need for new strategies to monitor and control a disease that had once seemed under control.