RIVM monitors the development of the flu virus in various ways. We call this ‘surveillance’. As part of these efforts, we work closely with Nivel, Erasmus University Medical Center (Erasmus MC) and laboratories in the Netherlands. We track how many people there are in the Netherlands with flu-like symptoms and look at which type of flu virus is most prevalent.

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Nivel monitoring stations: GPs report patients with flu-like symptoms

Nivel has commissioned a national network of GP practices to track how many patients visit their GP with flu-like symptoms each week. The GPs take samples from the throat and nose of some of these patients and send the samples to RIVM.

Research in the laboratory

RIVM conducts laboratory research to check whether the samples contain a flu virus. We also look at other viral pathogens, such as the respiratory syncytial virus (RSV), rhinovirus, enterovirus, coronavirus SARS-CoV-2 and some common cold viruses (human metapneumovirus, parainfluenza virus and other coronaviruses). If a sample does indeed contain a flu virus, RIVM or Erasmus MC investigate which type of flu virus it is.

Viruses and vaccines

Next, researchers examine the characteristics of the flu virus type. A specific protein is important in this process: hemagglutinin. This protein is found on the exterior surface of the virus and enables it to attach itself to human cells. Your body produces antibodies against this protein. Those antibodies provide protection. The study of these characteristics is key to finding out whether the flu vaccines that people receive are effective against the flu viruses that are circulating.

Weekly counts of virological notifications: laboratories report viruses

Each week, 21 laboratories in the Netherlands report the number of times a certain viral infection has been detected in patients. We call these the weekly counts of virological notifications. The counts also give information about the viruses that cause respiratory tract infections in the Netherlands, such as the flu virus and RSV. All participating laboratories are affiliated with the Netherlands Working Group for Clinical Virology, which is part of the Dutch Society for Medical Microbiology.

Monitoring infectious diseases in nursing homes

A network of nursing homes in the Netherlands allows us to track how infectious diseases develop in these facilities. We call this the Surveillance Network for Infectious Diseases in Nursing Homes (Surveillance Netwerk Infectieziekten Verpleeghuizen, SNIV). Each week, the participating nursing homes track how many people have flu-like symptoms, lower respiratory tract infections or COVID 19.

Dutch National Influenza Centre

The Dutch National Influenza Centre is a partnership between RIVM and Erasmus University Medical Center (Erasmus MC). A large number of hospital laboratories in the Netherlands send samples containing the flu virus to RIVM or Erasmus MC, where the type of flu virus is identified along with its characteristics. This is necessary to determine whether the available vaccines are effective against the viruses that are circulating.

Sharing information with the ECDC and the WHO

RIVM sends weekly reports to the European Centre for Disease Prevention and Control (ECDC) and the World Health Organization (WHO) regarding the number of flu cases in the Netherlands and the most prevalent virus types. Information on flu in other countries can be found on the ECDC and WHO websites.