Table. Pertussis incidence before, during and after the COVID-19 pandemic: interrupted time-series analysis, France, 2012–2024 (n = 26,060).

	Adjusted IRR^a	95% CI	p value
Overall number of positive PCRs (n = 26,060)
Pre-COVID-19	Reference
COVID-19 pandemic^b	0.09	0.06–0.13	< 0.001
Post-COVID-19	3.66	1.42–9.39	0.007
Number of positive PCRs, by age^c
0–5 years (n = 5,716)
Pre-COVID-19	Reference
COVID-19 pandemic^b	0.13	0.08–0.18	< 0.001
Post-COVID-19	3.29	1.28–8.48	0.014
6–17 years (n = 6,717)
Pre-COVID-19	Reference
COVID-19 pandemic^b	0.09	0.0–0.13	< 0.001
Post-COVID-19	4.58	1.79–11.76	0.002
≥ 18 years (n = 13,430)
Pre-COVID-19	Reference
COVID-19 pandemic^b	0.08	0.05–0.11	< 0.001
Post-COVID-19	3.62	1.41–9.29	0.008
Proportion of positive PCRs
Pre-COVID-19	Reference
COVID-19 pandemic^b	0.17	0.02–1.49	0.110
Post-COVID-19	1.86	0.19–17.96	0.591
Sensitivity analysis^d
Pre-COVID-19	Reference
COVID-19 pandemic^b	0.09	0.06–0.13	< 0.001
Post-COVID-19	3.52	1.34–9.27	0.011

CI: confidence interval; IRR: incidence rate ratio.

^a Negative binomial model adjusted on seasonality and 3-year pertussis cycles.

^b Between April 2020 and December 2023.

^c Age data were missing for 197 cases (less than 1%).

^d Seasonality-adjusted with calendar month instead of sine/cosine terms.