Wastewater-Based Surveillance of Respiratory Syncytial Virus Epidemic at the National Level in Finland

The purpose of this study was to evaluate the potential
of wastewater-based
surveillance in the monitoring of epidemics at the national level
in Finland. The 2021–2022 respiratory syncytial virus epidemic
in Finland was analyzed from wastewater and the Finnish National Infectious
Diseases Register. The study was performed using 150 samples that
were collected monthly from May 2021 to July 2022 from ten wastewater
treatment plants that cover 40% of the Finnish population. Respiratory
syncytial virus detection in 24 h composite samples of influent wastewater
was performed using reverse-transcription quantitative polymerase
chain reaction (RT-qPCR). Respiratory syncytial virus wastewater data
were positively correlated with the National Infectious Diseases Register-based
sampling week incidence (correlation coefficient, CC min = 0.412,
max = 0.865) and the four-week cumulative incidence (CC min = 0.482,
max = 0.814), showing the potential of wastewater-based surveillance
in estimating the course of epidemics. When the register-based incidence
of respiratory syncytial virus was at least four cases/100,000 persons/sampling
week, it was detected in all wastewater samples. This study showed
that wastewater surveillance can be used to surveil respiratory syncytial
virus epidemics at the national level, and its potential in the surveillance
of other epidemics should be explored further.