During the respiratory season 2024-2025 (week 40 of 2024 through week 20 of 2025), several viruses that can cause acute respiratory infections circulated, as usual for the winter period. The highest number of people with acute respiratory infections was observed during the period when influenza virus was widespread. In young children, the peak in respiratory infections coincided with the period when RS-virus (RSV) was circulating. During the winter, the coronavirus SARS-CoV-2 was not widely circulating. This virus mainly caused respiratory complaints during the summer and autumn of 2024. In cooperation with the National Intensive Care Evaluation (NICE) registry, the RIVM publishes information about respiratory infections that are severe enough to require admission to the intensive care unit (ICU). During the respiratory season 2024-2025, a peak in ICU admissions due to respiratory infections was observed during the period when influenza virus was widespread.
Coronavirus SARS-CoV-2 in the summer and autumn
Unlike influenzavirus and RS-virus, which are common in winter, the coronavirus SARS-CoV-2 does not (yet) have a stable seasonal pattern. The virus was mostly present in the summer and autumn of 2024. During these periods, the weekly number of hospital admissions with SARS-CoV-2 infection were lower than in periods in previous years when SARS-CoV-2 was widespread.
Mainly RS-virus around the turn of the year
Among children younger than five years of age, the number of GP visits for acute respiratory infections peaked just before and after the turn of the year. During the first peak, there also was an increase in GP visits for bronchiolitis in this age group. During this period, RS-virus was widespread. This virus was detected both in specimens from patients who visited the GP with an acute respiratory infection and in specimens from laboratories. From September 2025, babies born from April 2025 will be offered an immunisation against RS-virus. This is the first year this immunistion is available in the Netherlands. In countries where it has been offered for a longer period, the number of hospital admissions for young children with RS-virus infection has decreased significantly.
Flu epidemic started early 2025
The flu (influenza) epidemic lasted nine weeks; from mid-January to mid-March 2025. From early March, the number of people visiting the GP with flu-like symptoms was no longer increased, but laboratories still detected high levels of influenzaviruses. During the influenza epidemic, the number of ICU admissions for respiratory infections was increased. The most frequently detected influenza viruses during the 2024/2025 season were influenzavirus type A(H3N2) and type A(H1N1)pdm09.
Mortality
During the respiratory season, there was a period of excess mortality, which mostly coincided with the influenza epidemic. For the first time since the COVID-19 pandemic, there was no excess mortality during the surges of the coronavirus SARS-CoV-2 in summer and autumn 2024. Although excess mortality during the flu epidemic was slightly higher than last year, total excess mortality during the period July 2024 – June 2025 was slightly lower than in the same period the year before. Compared to the COVID-19 pandemic years, and the years before the pandemic, excess mortality in both July 2023–June 2024 and July 2024–June 2025 was relatively low.
Other viruses
Other viruses also caused respiratory infections in the 2024-2025 respiratory season. These included rhinovirus, human seasonal coronaviruses, human metapneumovirus (hMPV), and adenovirus. Although Mycoplasma pneumoniae was detected in more samples than usual during the 2023/2024 respiratory season, in 2024/2025 it returned to levels seen before the COVID-19 pandemic.
Monitoring respiratory viruses
We closely monitor the development and spread of respiratory infections in the Netherlands, in close collaboration with, amongst others, Netherlands Institute for Health Services Research (Nivel) and the laboratories of the Working Group on Clinical Virology (NWKV) of the Dutch Society for Medical Microbiology (NVMM). To better understand the severity of respiratory infections, RIVM is working with the NICE registry and Dutch Hospital Data (DHD), to set up hospital-based surveillance. Starting in September 2025, RIVM will publish weekly reports on the number of ICU admissions of adults due to respiratory infections. These data are provided by the NICE registry. This information is needed to assess the severity of a surge of infections during the respiratory season and can be important for responding to (unexpected) outbreaks.