RSV information and awareness platform Türkçe Frequently asked questions

For parents and clinicians

RSV season

RSV is not only a clinical heading; it is a seasonal public health event that concentrates in a narrow period and loads the health system abruptly. Knowing when the season arrives determines when protection must be planned.

Key message The RSV burden is both predictable and preventable, which turns the season into a time-limited opportunity for intervention.

When is the season in Türkiye?

The geographical and climatic diversity of Türkiye means the RSV season varies between regions. Existing surveillance data and clinician observations broadly indicate the following pattern:4

  1. October – November: rise

    Case numbers begin to climb. This is generally the appropriate window for pre-season preventive measures.

  2. December – February: peak

    The heaviest period. Emergency presentations, hospital admissions and intensive care demand pile up in these weeks.

  3. March – April: decline and close

    Case numbers fall and the season ends.

The seasonal pattern worldwide

RSV seasonal pattern — Türkiye and selected regions
RegionStartPeakEndSource
Türkiye (general)October – NovemberDecember – FebruaryMarch – AprilReference centre / sentinel
USA (north)OctoberDecember – FebruaryMarch – AprilCDC RSV-NET
Northern and Western EuropeSeptember – OctoberNovember – JanuaryMarchECDC sentinel network
Tropical regionsYear-round / rainy seasonVariable—WHO global surveillance

Note: data for Türkiye rest on reference centre and sentinel observations rather than systematic national surveillance; inter-regional differences have not been reported.

RSV occurs in all climate zones, but the shape of seasonal variation differs markedly by geography. In temperate climates the season runs from late autumn into spring, roughly October to April. In tropical and sub-tropical regions infections may continue year-round or show a distinct peak coinciding with the rainy season.1

A two-season multicentre epidemiological study conducted in Türkiye found that RSV activity correlates positively with relative humidity and rainfall and negatively with temperature. The researchers emphasised that countries need viral surveillance systems suited to their own climatic and epidemiological characteristics.7

What happens at the peak?

  • 3–5× Increase in RSV-related hospital presentations at peak compared with off-season periods CDC, 2023; ECDC, 2022
  • 4–6× How much higher admission rates run in infants aged 0–12 months during peak weeks, compared with the general paediatric population Shi et al., 2017
  • 20–40% Share of admitted children who may acquire RSV on the ward during epidemics French et al., 2021

What matters systemically is this: the RSV burden piles up abruptly and intensely in particular weeks. When that rise coincides with influenza and other respiratory infections, it lands on the health system as a cumulative pressure that cannot be assessed through any single aetiology.23

RSV and influenza peaking in the same weeks affects emergency departments, paediatric wards and paediatric intensive care units simultaneously. This overlap can produce a picture in which burden levels that look acceptable individually exceed the health system's management capacity when taken together.612

That pressure cannot be measured in beds and equipment alone. The sharp rise in workload at peak also raises the risk of physical and emotional burnout among health workers.11

The window the season opens

An effective preventive strategy should aim to reduce burden before it arises, rather than respond after it has.

The predictable structure of the RSV season should be read not only as a risk factor but as an opportunity window for strategic intervention.

The practical consequence is this: for preventive approaches to be effective, the intervention must be delivered before the season — in a window before the peak arrives. Interventions started mid-season or after the peak cannot realise their theoretical potential.

Given that activity in Türkiye concentrates in December–February, the appropriate window for pre-season immunisation generally falls in October–November. Individual timing depends on the approach chosen, the pregnancy or birth date, the baby's age and current national recommendations.

Related pages

Sources

  1. World Health Organization (WHO). (2022a). RSV global epidemiology and burden of disease. WHO.
  2. Centers for Disease Control and Prevention (CDC). (2023). RSV-NET: RSV Hospitalization Surveillance Network. CDC.
  3. European Centre for Disease Prevention and Control (ECDC). (2022). Respiratory syncytial virus infection — Annual epidemiological report. ECDC.
  4. T.C. Sağlık Bakanlığı Halk Sağlığı Genel Müdürlüğü. (t.y.). Haftalık solunum yolu virüsleri sürveyans raporları. HSGM.
  5. Shi, T., McAllister, D. A., O'Brien, K. L., Simões, E. A., Madhi, S. A., Gessner, B. D., ve ark., & Nair, H. (2017). Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in young children in 2015: A systematic review and modelling study. The Lancet, 390(10098), 946–958. doi.org/10.1016/S0140-6736(17)30938-8
  6. Mazur, N. I., Martinon-Torres, F., Baraldi, E., ve ark. (2015). Lower respiratory tract infection caused by respiratory syncytial virus: Current management and new therapeutics. The Lancet Respiratory Medicine, 3(11), 888–900. doi.org/10.1016/S2213-2600(15)00388-6
  7. Turkish Neonatal Society. (2012). The seasonal variations of respiratory syncytial virus infections in Turkey: A two-year epidemiological study. The Turkish Journal of Pediatrics, 54(3), 216–222.
  8. Çoban, Y., Evren, G., Yıldızdaş, D., Zengin, N., Bal, L., Kendirli, T., ve ark., & Dinleyici, E. Ç. (2026). Burden, risk factors, and outcomes of respiratory syncytial virus (RSV) infection in pediatric intensive care units in Türkiye (RSVP Study 2020–2024). BMC Pediatrics, 26(1), Article 298. doi.org/10.1186/s12887-026-06562-7
  9. Centers for Disease Control and Prevention (CDC). How RSV spreads. www.cdc.gov/rsv/causes/index.html · 2026-08-04
  10. European Centre for Disease Prevention and Control (ECDC). (2025a). Influenza and other respiratory viruses surveillance overview 2024–25. ECDC.
  11. Gribben, V., Deonandan, S., & Geng, E. (2023). Pediatric healthcare worker burnout and stress during seasonal respiratory surges. JAMA Pediatrics, 177(4), 345–352. doi.org/10.1001/jamapediatrics.2022.6074
  12. Varela, S., Chaves, T., & Broberg, E. K. (2024). The double burden of RSV and influenza co-circulation: Impact on pediatric workforce and healthcare system resilience. Eurosurveillance, 29(2), 23–31. doi.org/10.2807/1560-7917.ES.2024.29.2.2300011

All topics →

The information on this site is for general guidance only and does not replace examination, diagnosis or treatment by a clinician.