Pertussis hospitalizations in France (2008-2020): A real-world retrospective analysis of incidence and costs based on the French National Health Data System.

BACKGROUND

Assessing pertussis burden and the impact of the 2013 vaccination schedule update (3 + 1 to 2 + 1 schedule) in France is hindered by non-mandatory reporting. We aimed to estimate the cumulative incidence and hospitalization costs due to pertussis in France between 2008 and 2020.

METHODS

This observational retrospective cohort study was conducted using claims data from the French National Health Data System (SNDS) (January 2008-December 2020). Cumulative incidence of pertussis-hospitalizations, cumulative incidence ratios, and economic burden were analyzed. Cumulative incidences were estimated as the total pertussis-hospitalizations recorded annually from SNDS with respect to the French population, and expressed per 100,000 inhabitants. Cumulative incidence ratios were estimated using a negative binomial regression adjusted on the cyclical pattern of pertussis disease.

RESULTS

Overall, 10,893 patients were hospitalized for pertussis (severe cases: 36.7 % [n = 3997]; Bordetella pertussis disease: 93.3 % [n = 10,158]). Outbreaks were reported in 2009 (n = 1276), 2012-2013 (n = 2762), and 2017-2018 (n = 1727). The age group with the highest proportion of cases was 2-5 months (34.7 %), followed by 0-1 month (18.0 %) and ≥65 years (13.6 %). Cumulative incidence of hospitalization due to Bordetella pertussis disease was similar among infants aged <2 and 2-5 months (cumulative incidence ratio [CIR]=0.96 [0.90-1.02]; comparator: <2 months) and quite low in children aged ≥1 year (CIR≤0.01). Among adults, CIRs increased with age and peaked at ≥65 years (CIR=2.95 [2.57-3.38]; comparator: 18-25 years). CIRs decreased post schedule change (CIR=0.61 [0.43-0.84]; comparator: 3 + 1) and post-implementation of mandatory vaccination policy (CIR=0.68 [0.43-1.08]; comparator: before mandatory vaccination policy) across all age groups. Median overall costs were €3259 (all cases), with higher costs for severe cases and highest costs (€4880) for infants aged <2 months.

CONCLUSION

Results reemphasized the persistent public health challenge of pertussis, especially in infants aged 0-5 months. Findings may guide future vaccination policies in Europe.