The Netherlands is experiencing a flu epidemic. The number of people with flu (influenza) increased significantly in the past two weeks. Laboratories, hospitals and GPs throughout the country report that the flu virus has been turning up in more throat and nasal samples from people with flu-like symptoms. More and more people contact their GP with flu-like symptoms. In addition to the flu virus, several other viruses that cause respiratory symptoms are currently circulating in the Netherlands. They include the respiratory syncytial virus (RSV), the SARS-CoV-2 virus (coronavirus), the human metapneumovirus and the rhinovirus.
Each week, 19 laboratories in the Netherlands report the number of patients with a particular viral infection, including infection with the flu virus. For the second consecutive week, these laboratories have reported a significant increase in the number of people who have the flu. Laboratories have also been sending more flu samples to the Dutch National Influenza Centre to identify specific strains of the flu virus. Lastly, GPs have seen a growing number of people with flu-like symptoms who indeed have the flu, according to information from the Nivel monitoring stations. All of this information together indicates that there is a flu epidemic.
Flu epidemic threshold
In the Netherlands, the normal threshold for declaring a flu epidemic is as follows: more than 58 in 100,000 people visit their GP with flu-like symptoms for two weeks in a row, and at least 10 per cent of those people are indeed infected with the flu virus. This is monitored by the Nivel monitoring stations. As was the case during the winter of 2021–2022, it is currently difficult to establish if there is a flu epidemic based on these figures alone. This is because the symptoms of the flu strongly resemble those of COVID-19. Many people with flu-like symptoms are currently self-testing for the coronavirus, which may make them less likely to consult a GP. Although the threshold of 58 in 100,000 people visiting their GP with flu-like symptoms has not been reached yet, the Nivel monitoring stations have noted a sharp increase in patients with flu-like symptoms. RIVM has also detected flu viruses in a growing number of these patients’ samples.
About the flu
The onset of ‘real’ flu (influenza) is usually quite sudden, with cold shivers, a runny nose, a headache, severe muscle aches and fatigue, a sore throat, a dry cough and a fever. The patient’s body temperature may quickly rise to 39 °C or higher. In addition to the flu (influenza) virus, various other respiratory viruses can also cause flu-like symptoms. They include the respiratory syncytial virus (RSV), the SARS-CoV-2 virus (coronavirus), the human metapneumovirus and the rhinovirus. These viruses also cause symptoms such as a runny nose, a sore throat, a headache, a cough and possibly a fever.
Getting a flu vaccine offers the best protection against serious complications of the flu. The basic recommendations to prevent the spread of the coronavirus also work to prevent the spread of the flu virus. Washing your hands frequently, coughing and sneezing into the fold of your elbow and social distancing reduce the risk of passing the virus to others. The same goes for other respiratory viruses, such as RSV, the human metapneumovirus and the rhinovirus. This is especially important when coming into contact with vulnerable groups of people, such as the elderly and young children. They can become seriously ill from the flu virus and other respiratory viruses.
At the Dutch National Influenza Centre, RIVM, Nivel and the Erasmus MC monitor the development of the flu virus in the Netherlands on an ongoing basis. They also take part in international networks of the World Health Organization (WHO) and the European Centre for Disease Prevention and Control (ECDC).