Estimating the Incidence of First RSV Hospitalization in Children Born in Ontario, Canada

Abstract

Background Respiratory syncytial virus (RSV) contributes significantly to morbidity in children, placing substantial burdens on health systems, thus RSV vaccine development and program implementation are a public health priority. More data on burden are needed by policymakers to identify priority populations and formulate prevention strategies as vaccines are developed and licensed. Materials/methods Using health administrative data, we calculated incidence rates of RSV hospitalization in a population-based birth cohort of all children born over a six-year period (May 2009 - June 2015) in Ontario, Canada. Children were followed until their first RSV hospitalization, death, 5 th birthday, or the end of the study period (June 2016). RSV hospitalizations were identified using a validated algorithm based on International Classification of Diseases, 10 th Revision, and/or laboratory-confirmed outcomes. We calculated hospitalization rates by various characteristics of interest, including calendar month, age groups, sex, comorbidities, and gestational age. Results The overall RSV hospitalization rate for children <5 years was 4.2 per 1,000 person-years (PY) with a wide range across age groups (from 29.6 to 0.52 per 1000PY in children aged 1 month and 36-59 months, respectively). Rates were higher in children born at a younger gestational age (23.2 per 1000PY for those born at <28 weeks versus 3.9 per 1000PY born at ≥37 weeks); this increased risk persisted as age increased. While the majority of children in our study had no comorbidities, rates were higher in children with comorbidities. For all age groups, rates were highest between December and March. Conclusions Our results confirm the high burden of RSV hospitalization and highlight young infants are at additional risk, namely premature infants. These results can inform prevention efforts.

Burden of disease of RSV in infants, children and pregnant women and people

“…Buchan et al reported 5% ICU admission for healthy children younger than five years, increasing to 10% with comorbidities (( 18 )). In their 2023 study, ICU admission reached 8.1% among RSV-hospitalized children under five, with higher rates for premature births (( 13 )). In one Canadian study, ICU admission was more common with RSV compared to influenza (( 19 )).…”

“…An Ontario study by Pisesky et al reported RSV hospitalization rates of 10.2 per 1,000 children younger than one year and 4.8 per 1,000 in children one to three years of age (( 12 )). Buchan et al ’s Ontario cohort study revealed varying RSV hospitalization rates across age groups, with the highest in one-month-olds (n=29.55 per 1,000) and declining with age, with rates highest among children born at younger gestational ages (( 13 )). Over five respiratory seasons from 2018 to 2023 in Yukon, there were 27 severe RSV cases (non-ICU hospitalizations, ICU admissions and deaths), of which 18 were non-ICU hospitalizations.…”

“…An overall mortality rate of 0.6 per 100,000 population was reported by Schanzer et al ’s 2018 Canadian model of all patients in Canada admitted to hospital with a respiratory condition (from infancy to older than 65 years) (( 20 )). Buchan et al ’s 2023 Ontario cohort found a 0.2% mortality rate within 30 days of discharge from RSV hospitalization (( 13 )). In the US, an infant cohort followed from 1999 to 2018 showed a RSV mortality rate of 6.9 (95% CI: 6.4–7.5) per one million live births, with preterm infants at the highest risk (( 21 )); however, the majority of deaths occurred in full-term infants (53.7%), primarily those between one and four months of age (63.8%).…”

A Health Economic Evaluation for Implementing an Extended Half-life Monoclonal Antibody for All Infants vs. Standard Care for Respiratory Virus Syncytial Prophylaxis in Canada

“…36–39 Due to this monthly change in viral risk combined with granularity in palivizumab and nirsevimab’s current indications for use in Canada, we strived to utilize monthly data inputs from Canada in our model. Given the lack of such data and the common seasonality of RSV and similar incidence in infants in Canada and the United States, 40,41 we opted to extrapolate US-based health outcomes and cost inputs and modify them using average Canadian values. Incorporating monthly data inputs was deemed critical to the ability of our model to estimate the clinical and cost impact of nirsevimab vs. standard care.…”

Cost-effectiveness of RSVpreF vaccine and nirsevimab for the prevention of respiratory syncytial virus disease in Canadian infants

“…The rates of RSV-associated hospitalizations by gestational age at birth were derived from a systematic review (17). Case-fatality and age-specific background mortality rates were obtained from the literature (3, 18, 19). The case-fatality rate was adjusted to account for background mortality.…”