OBJECTIVES: To compare wastewater surveillance- (WWS) versus clinical surveillance (CS)-guided respiratory syncytial virus (RSV) prophylaxis programs in Ontario, Canada.

METHODS: A cost-consequence model was developed that considered all infants aged <6 months at the start of the RSV season and eligible for nirsevimab prophylaxis. The RSV season was determined to start one month earlier using WWS than CS and, in both scenarios, lasted for 5 months. Nirsevimab efficacy at preventing RSV-related hospitalizations (RSVH), medically-attended emergency room/outpatient RSV infections (MARI) and subsequent respiratory morbidity (RM) was adjusted in the CS scenario by having one month at the no-prophylaxis rate (to reflect a one-month delay in timing of prophylaxis initiation versus WWS). The RSVH rate was 0.6% for WWS versus 0.8% for CS in prophylaxed infants (no prophylaxis: 1.6%). Assuming that RSV-WWS was added to an existing provincial WWS system, the cost was budgeted at $76,840/year, whereas for setting-up a new system, the cost was $1.47m in the first year and $810,560 in subsequent years. For CS, no additional costs were assumed. Other costs considered included (equivalent for both WWS and CS): nirsevimab ($952.28 for 50/100g vials + $14.37 nurse administration); RSVH episode ($8,353); intensive care unit episode ($5,747); MARI episode ($91-337); and RM episode/year ($1,116). All costs are in 2022 Canadian dollars.

RESULTS: Of 136,571 annual Ontario live births, 124,728 infants were estimated to be <6 months at the start of the RSV season and thereby eligible for nirsevimab prophylaxis. Compared to CS, WWS was associated with savings of $2.1-3.5m in the first year and $13.7-16.6m over 1-3 years (Table). WWS-guided prophylaxis resulted in 249 fewer RSVHs and 950 fewer MARIs per year versus CS-guided prophylaxis.

CONCLUSIONS: WWS has the potential to more accurately detect the start of the pediatric RSV season, which could significantly increase the effectiveness of prophylaxis programs while saving healthcare costs.