RSV Is Seasonal, With Peak Incidence Varying by Region1,2

  • Temperate countries in the Northern Hemisphere generally experience the start of the RSV season between September and January.
  • Those in the Southern Hemisphere generally experience the start of the RSV season between March and June, closely aligned with colder temperatures.
  • The seasonality of RSV in (sub)tropical climates appears less consistent—with studies indicating peak of RSV season closely aligns with the rainy season and/or higher temperatures.
    1. Staadegaard L, et al. Influenza Other Respir Viruses. 2021;10.1111/irv.12885. 2. Obando-Pacheco P, Justicia-Grande AJ, et al. J Infect Dis. 2018;217(9):1356-1364.

RSV is a highly transmissible viral disease

RSV is transmitted by respiratory droplets and considered “highly contagious”9-11

R0 of  4.5
mean R0 ranging from 1.7 to 8.212

    2. Lessler J, et al. Lancet Infect Dis. 2009;9(5):291-300.
    3. Piedimonte G, Perez MK. [published correction appears in Pediatr Rev. 2015 Feb;36(2):85]. Pediatr Rev. 2014;35(12):519-530.
    4. Smith DK, Seales S, Budzik C. Am Fam Physician. 2017;95(2):94-99.
    5. RSV Symptoms and Diagnosis; available at Accessed on 11th of May 2022.
    6. Heylen E, Neyts J, Jochmans D. Biochem Pharmacol. 2017;127:1-12.
    7. Carvajal JJ, et al. Front Immunol. 2019;10:2152.
    8. Respiratory Syncytial Virus Infection (RSV); available at Accessed on 23rd February 2022.
    9. Heylen E, Neyts, J, Jochmans, D. Biochem Pharmacol. 2017;127:1-12.
    10. Carvajal JJ, et al. Front Immunol. 2019;10:2152.
    11. Drajac C, et al. J Immunol Res. 2017;2017:8734504.
    12. Reis J, Shaman J. Infect Dis Mod. 2018;3:23-34.
    13. Hirono O et al American Journal of Epidemiology, Volume 190, Issue 12, December 2021, Pages 2536–2543,
    14. Takeyama A et J Med Virol. 2016 Jun;88(6):938-46. doi: 10.1002/jmv.24434. Epub 2015 Dec 1. PMID: 26588816.
    15. Lehners N et. PLoS One. 2016 Feb 11;11(2):e0148258. doi: 10.1371/journal.pone.0148258. PMID: 26866481; PMCID: PMC4750950.
    16. Piedimonte G. Curr Opin Pediatr. 2013 Jun;25(3):344-9. doi: 10.1097/MOP.0b013e328360bd2e. PMID: 23657245; PMCID: PMC3889210.
    17. Glezen WP, et al. Am J Dis Child. 1986;140(6):543-546.
    18. Hall CB, et al. Clin Infect Dis. 2001;33(6):792-796.

RSV shedding in Infants, toddlers and immunecompromised

Duration of Virus Shedding in Infants and Toddlers

Duration of Virus Shedding in Immunecompromised patients

    1. Takeyama A et al J Med Virol. 2016 Jun;88(6):938-46. doi: 10.1002/jmv.24434. Epub 2015 Dec 1. PMID: 26588816.
    2. Lehners N, et al.. PLoS One. 2016;11(2):e0148258. Published 2016 Feb 11.doi:10.1371/journal.pone.0148258

Most Infants Are Exposed to RSV Infection in the Community and Through Other Children1-3

Crowding and
day-care exposure
increased the risk
of severe RSV

In the United States, more than 50 per cent of under-ones are in some form of childcare; ~75% from the age of 4 months7

Network showing the sources of infection to the infant, as identified by social relationships in Kenya.1 The size of the circles is proportional to the number of cases.

    1. Adapted from Kombe IK, et al. Sci Rep. 2021;11(1):1463.
    2. Thomas E, et al. J Infect Dis. 2021;223(5):811-817.
    3. Hall CB, et al. N Engl J Med. 1976;294(8):414-419.
    4. Bont L, et al Infect Dis Ther. 2016 Sep;5(3):271-98. doi: 10.1007/s40121-016-0123-0. Epub 2016 Aug 1. PMID: 27480325; PMCID: PMC5019979.
    5. Sommer C et al. Open Microbiol J. 2011;5:144-154. doi:10.2174/1874285801105010144.
    6. Colosia, A.D et al. BMC Infect Dis 12, 95 (2012).
    7. Unicef report card 8;The child care Transition ,A league table of early childhood education and care in economically advanced countries rc8_eng.pdf (