Early Peak of RSV

Based on RSV detections reported by laboratories (virological laboratory surveillance), the RSV season 2023/2024 began in week 39. This is similar to the 2022/2023 season and earlier than the five pre-pandemic RSV seasons (2014/2015 – 2018/2019). The peak during the respiratory season 2023/2024 (week 48) was earlier than the peak of the respiratory season 2022/2023 (week 52) and the five pre-pandemic respiratory seasons (between weeks 52 and 8). Other RSV surveillance sources showed similar trends for the 2023/2024 season, with peaks between weeks 45-48 of 2023. In the virological laboratory surveillance and the Nivel general practitioner (GP) sentinel surveillance, the peaks were earlier in the season than during the five pre-pandemic seasons (2014/2015 to 2018/2019). The peaks in the virological laboratory surveillance and in the number of hospital admissions among young children were also earlier than the previous season 2022/2023. 

RSV Detections in virological laboratory surveillance

The number of RSV detections reported by the laboratories of the virological laboratory surveillance began to increase just before the start of the respiratory season (since week 36 of 2024) and peaked in week 48, 2023. Between week 48, 2023, and week 2, 2024, the number of detections decreased sharply (from 374 to 103 weekly detections). After week 2, the number of detections gradually decreased further. Between March 2024 (week 10, 2024) and the end of this reporting period (week 20, 2024), it remained at a low level. Since the testing policy has likely changed since the COVID-19 pandemic, the number of RSV-positive tests should be interpreted with caution. This also applies to the indicators used to define the start, intensity, and end of the RSV seasons. These indicators are calculated using the Moving Epidemic Method (MEM) based on reported detections from the virological laboratory surveillance in the seasons 2010/11 to 2019/20 (see table below).

RSV at the general practitioner

The percentage of RSV-positive specimens collected in the GP sentinel surveillance from patients with an acute respiratory infection (ARI) peaked in week 48, 2023 (20% of specimens positive). This was similar to the respiratory season 2022/2023 but earlier than the five pre-pandemic respiratory seasons. In the weeks after week 51, 2023, RSV was only found sporadically. The percentage of RSV-positive specimens was highest among children aged 0-1 year (26%), followed by the age group 2-4 years (19%), 5-14 years (8%), 65 years and older (6%), 45-64 years (5%), and 15-44 years (3%). RSV-A was dominant in all age groups in the GP sentinel surveillance throughout the respiratory season 2023/2024.

RSV in Infectieradar

In the specimens from the Infectieradar self-sampling study, the highest percentages of RSV in people with ARI were found in weeks 46-52. The peak percentage was 6% in week 47. It should be noted that there is a strong underrepresentation of children in Infectieradar. As in the GP sentinel surveillance, RSV-A was dominant in all age groups in Infectieradar throughout the respiratory season 2023/2024. 

RSV hospital admissions in young children

The number of children under two years admitted with RSV bronchiolitis peaked in week 45, 2023 (n = 191 hospital admissions) in 43 hospitals participating in the SPREAD study (see also background and methods). Unlike the virological laboratory surveillance, this peak was higher than in the season 2022/2023 (n = 143 hospital admissions). Data collection for the SPREAD study stopped in week 18, 2024.