Since the start of the flu season in October 2021, the flu virus has been found very occasionally in the Netherlands. This infrequent occurrence is probably due to the coronavirus measures, which also prevent the flu virus from spreading. Now that many measures have been discontinued, people are having contact with others more often again. This also increases the risk of respiratory infections such as flu.

Uncertainty regarding normal criteria for flu epidemic

In the Netherlands, an outbreak of influenza is considered a flu epidemic when more than 58 in 100,000 people go to their GP with flu-like symptoms and at least 10% of these people have the influenza virus, and this persists for two weeks in a row. This is monitored by the Netherlands Institute for Health Services Research (Nivel) and RIVM. Through a national network, GP practices report how many people they see with flu-like symptoms. They take throat and nose samples from some of these people. Laboratory testing is performed to determine whether they actually have the flu virus. The symptoms of influenza are very similar to those of the coronavirus SARS-CoV-2. Therefore, people who have flu-like symptoms are currently going to a GGD test lane or using a COVID-19 self-test. Fewer people with respiratory infections are going to their GP compared to previous years. As a result, the normal criteria for identifying a flu epidemic are very uncertain in this situation.

Information from laboratories, hospitals and GGDs

RIVM is also monitoring trends in the influenza virus in other ways. Various laboratories in the Netherlands reported last week that the number of people with flu is increasing significantly. Since November 2021, some of the samples for COVID-19 from the GGD test lanes in Amsterdam and Utrecht have been examined to check for influenza viruses. These results also show an upward trend. Finally, various hospitals report rising numbers of people with flu. Based on this information, a flu epidemic seems to be emerging. RIVM, Nivel and Erasmus MC are carefully monitoring the further development of this situation.

Flu and COVID-19

Flu and COVID-19 are both infections of the respiratory system. However, they are caused by different viruses. Both viruses spread through droplets that are released during coughing or sneezing. In addition, both viruses cause fever, cold symptoms and coughing, and sometimes lead to pneumonia.
The basic measures to prevent the coronavirus SARS-CoV-2 from spreading are also effective in preventing the spread of the influenza virus. Washing your hands regularly, coughing and sneezing into your elbow, and distancing all help reduce the risk of transmitting the virus to others. Keep this in mind, especially when interacting with vulnerable groups of people. They could become seriously ill from the influenza virus.