Key Points

After a steady increase since March 2024 and stabilization at very high levels this summer, pertussis surveillance has shown a significant decline since September in all routinely monitored epidemiological indicators.

Although the level of bacterial circulation remains higher than in previous years, these declines nonetheless signal the end of the 2024 cycle.

As of November 15, 2024 (week 45), the various pertussis surveillance indicators tracked by Santé publique France show the following trends:

• In primary care

  • Data from the Sentinelles network indicate that after peaking in the last week of June, weekly incidence rates have been declining since September. For the year 2024 (weeks 1–45), the cumulative number of pertussis cases seen in primary care was estimated at 156,551 [95% CI: 143,444; 169,658].

  • The weekly number of SOS Médecins calls for a diagnosis of pertussis rose steadily until June, then remained stable throughout the summer; it has been declining since September across all age groups and regions and is now at the levels seen in late May (W22).

• In hospitals

  • After 33 weeks of increases since the start of the year, the weekly number of emergency department visits has been decreasing since mid-August across all age groups and regions. The figures observed in early November 2024 remain very high compared to the 2017–2018 season.

  • Since week 34 (late August), the number of hospitalizations following emergency room visits has also fallen sharply, although it remains at high levels compared to previous years and has returned to levels comparable to those in March and April 2024.

  • The RENACOQ network reports a cumulative total of 305 infants under 12 months hospitalized for 2024 (January 1 to November 10), of whom 244 (80%) were under 6 months old—a figure higher than those reported during the last peaks in 2012 and 2017.

• Activity data from private clinical laboratories (3Labos data): after reaching a peak of 28.8% in August, the positivity rate has been declining since September. It stood at 14.3% in September and 7.6% in October, a rate comparable to that observed in January 2024.

• A provisional total of 42 deaths has been reported since the beginning of 2024, including 23 children (20 under 1 year of age) and 19 adults (13 of whom were 80 years of age or older).

• Regarding monitoring of B. pertussis resistance to macrolides, 17 resistant samples have been characterized at the CNR since the beginning of 2024 (1.9%, 17/891), with 4 additional resistant strains detected over the last 2 months (September and October).

The peak of the 2024 pertussis cycle appears to have been reached in August, given the decline observed in all monitored indicators over the past three months. Although all values have returned to levels comparable to those of the second quarter of 2024, they remain above what was observed during the last epidemic cycle in 2017–2018.