Severe RSV-related IIlness among Ontario Children: Using Population-based, Administrative Data to Comprehensively Identify High-risk Children and Evaluate Population Interventions

Respiratory syncytial virus (RSV) is the most common cause of respiratory tract infection and hospitalization among children globally. Early-life infection with RSV has long-term impacts, including increased risk of developing asthma, and there is increasing recognition of the burden RSV imposes upon the health of older adults. In this dissertation, I present three studies pertaining to the epidemiology and prevention of severe RSV-related illness, particularly among young children, using unique multi-linked health and socio-demographic administrative data for the population of Ontario, Canada. Using a quasi-experimental design, I evaluated the effectiveness of RSV prophylaxis programs for high-risk infants. Severe RSV-related illness substantially declined over the 24-year study period, particularly among high-risk children. While we cannot firmly attribute causality, the magnitude and timing of changes, along with diminished social inequities, among prophylaxis-eligible infants are noteworthy and suggest these programs have noticeable real-world effectiveness, albeit to a lesser degree than observed in efficacy studies. In a birth cohort study, I investigated the contribution of multiple socio-demographic factors to early-life RSV admissions. To date, these factors have received little attention relative to medical factors, despite the known role they have in influencing the transmission, severity and uptake of interventions for other common respiratory viruses. Multiple novel socio-economic factors were independently associated with significantly greater RSV-related admission rates, including young maternal age, maternal involvement with the criminal system, and maternal mental health and/or addiction concerns. I developed the first RSV transmission model for any Canadian population, which also uniquely captures the entire population age spectrum. Relative to other common communicable diseases, few RSV transmission models exist. Our model accurately captured the seasonal RSV epidemic curves observed among infants and suggests RSV burden is greatest at the extremes of the age spectrum. This calibrated base model can be adapted to investigate the potential impacts of emerging RSV vaccination strategies in Ontario and could be further calibrated for use in other populations. Overall, these results contribute to our understanding of the real-world impact of RSV prophylaxis programs and highlight impactful targets for revisions to prophylaxis guidelines and emerging vaccination strategies. These results may inform the selection of optimal policies and interventions which not only reduce RSV burden but also minimize social inequities.Ph.D.2021-11-30 00:00:0