Introduction
RSV is the leading cause of acute lower respiratory tract infections (LRTls) in infants and also induces significant disease in the elderly.^1,2 There is currently no approved vaccine against RSV.¹ Currently, the only treatment option available for RSV is Palivizumab which is expensive, has moderate effectiveness, and its usage is limited to high-risk individuals.^1,2

Disease burden
Global
A study conducted by Li et al. estimated that globally in 2019, there were 33 million RSV-associated acute LRTls episodes,
3.6 million RSV-associated acute lower respiratory infection hospital admissions, 26,300 RSV-associated acute lower
respiratory infection in-hospital deaths, and 101,400 RSV attributable overall deaths in children aged 0-60 months⁴

Canada
RSV-associated hospitalization rates in Canada are 1 to 2 per thousand infants under 1 year of age with the Arctic region
accounting for high rates of RSV and hospitalizations.⁵ An article by Thampi et al. showed that 1% of newborns in Canada are hospitalized in the first year of life, with RSV infections accounting for 9°/o of all hospital admissions among infants for causes not related to birth.^1,2 As per the Respiratory Virus Detection Report, RSV (1,824 detections from 26999 samples tested; 6.8% positive) was the most common seasonal respiratory viruses detected in Canada in week5 2 (December 26, 2021 t0 January1, 2022).

Unites States
Every year in the United States, RSV leads to approximately:
• 2.1 million outpatient visits among children younger than 5 years old⁸
• 58,000 hospitalizations among children younger than 5 years old⁸
• 177,000 hospitalizations among adults 65 years and older⁹
• 14,000 deaths among adults 65 years and older^8,9

Inference
RSV infections accounts for high percentage of hospital admissions in infants and is the most common respiratory viruses detected in Canada. The only available mAb has its own set of challenges and limitations.

References:

1. Biagi C, Don di A, Scarpini S, et al. Current State and Challenges in Developing Respiratory Syncytial Virus Vaccines. Vaccines (Basel). 2020; 8(4):672. Published 2020 Nov 11. doi:10.3390/vaccines8040672.
2. Ananworanich J, Heaton PM. Bringing Preventive RSV Monoclonal Antibodies to Infants in Low- and Middle-Income Countries: Challenges and Opportunities. Vaccines (Basel). 2021;9(9):961. Published 2021 Aug 28. doi:10.3390/vaccines9090961.
3. Soto JA, Stephens LM, Waldstein KA, Canedo-Marroqufn G, Varga SM, Kalergis AM. Current Insights in the Development of Efficacious Vaccines Against RSV. Front lmmunol. 2020;11:1507. Published 2020 Jul 17. doi:10.3389/fimmu.2020.01507.
4. Li Y, Wang X, Blau DM, et al. Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in children younger than 5 years in 2019: a systematic analysis. Lancet. 2022;399(10340):2047-2064. doi:10.1016/So140-6736 (22)00478-0.
5. Nourbakhsh S, Shoukat A, Zhang K, et al. Effectiveness and cost-effectiveness of RSV infant and maternal immunization programs: A case study of Nunavik, Canada. EClinicalMedicine. 2021;41:101141. Published 2021 Sep 24. doi:10.1016/j.eclinm.2021.101141.
6. Tham pi N, Knight BD, Thavorn K, et al. Health care costs of hospitalization of young children for respiratory syncytial virus infections: a population-based matched cohort study. CMAJ Open.2021;9(4):E948-E956. Published 2021 Oct 19. doi:10.9778/cmajo.20200219.
7. Respiratory Virus Report, week 52 – ending January 1, 2022. https://www.canada.ca/en/public-health/services/surveillance/respiratory-virus detections-canada /2021-2022/week-52-ending-january-1-2022.html. Last accessed 16th July 2022.
8. Trends and Surveillance. https://www.cdc.gov/rsv/research/us-surveillance.html. Last accessed 18th July 2022.
9. Balasubramani GK, Nowalk MP, Eng H, Zimmerman RK. Estimating the burden of adult hospitalized RSV infection using local and state data-methodology. Hum Vaccin lmmunother. 2022;18(1):1958610. doi:10.1080/21645515.2021.1958610.