Coinfections and iterative detection of respiratory viruses among 17,689 patients between March 2021 and December 2022 in Southern France.

Objectives: We aimed to describe coinfections and iterative infections with respiratory viruses diagnosed over a 22-month period in 2021-2022 in public university hospitals of the second largest French city.

Material And Methods: Respiratory virus infections were diagnosed by qPCR with the Fast Track Diagnostics Respiratory Pathogens 21 on nasopharyngeal swabs collected between 01/03/2021-31/10/2022 and sent for routine diagnosis purpose to our clinical microbiology-virology laboratory at public university hospitals of Marseille, Southern France.

Results: Nasopharyngeal swabs from 17,689 patients were tested, of which 8,133 (46 %) were positive for ≥1 respiratory virus and 1,255 (15%) were co-infected with ≥2 viruses including 213 (2.6 %) with 3-7 viruses. Among them, 1,005 (80 %) were younger than 5 years, and mean age was significantly lower for coinfected than monoinfected patients (6.6 versus 23.8 years; p < 0.0001). Viruses with the highest confection rates were HBoV (97 %), HPeV (97 %), EV (92 %), ADV (68 %), and HCoV-HKU1 (63 %). Iterative infections were observed in 96 patients and they involved 10 different viruses.

Conclusions: Our study points out that coinfections with respiratory viruses vary over time in prevalence, involve majoritarily young children, and may involve concurrent acute infections or acute-on-chronic infections, which deserves further specific studies.