Flu season does not have a fixed start date, with annual epidemics in Europe typically occurring between November and April. While sporadic cases can occur outside these months, the exact start, duration, and peak differ per season.
Understanding Flu Symptoms and Spread
A few people with fevers do not mean the flu season is fully underway, as the spread is tracked using medical data and laboratory research. Not every cold is the flu, as various respiratory viruses can cause similar symptoms. Influenza typically begins suddenly with fever, muscle aches, headaches, and significant fatigue, whereas a runny nose alone does not indicate which virus has been contracted.
Vaccination and Timing
For individuals for whom a flu vaccine is recommended, vaccination should be planned before transmission increases strongly. In Flanders, the recommended vaccination period runs from mid-October to the end of November. The body needs about ten to fourteen days after the shot to build protection, meaning a person is not immediately protected upon leaving.
Vaccination is particularly important for those at higher risk of becoming seriously ill, including older adults, individuals with certain chronic conditions or a weakened immune system, and pregnant persons. Because flu viruses change and protection diminishes, annual vaccination is necessary, and last year’s vaccination does not replace this autumn’s dose.
Preventative Measures and Ventilation
Flu viruses spread through the air when infected people talk, cough, or sneeze, and hands can also play a role. Protection works best when multiple measures are combined, as washing hands alone while sitting closely to a sick person for a long time does not remove the full risk. Indoor spaces should be ventilated even as it gets colder outside by keeping ventilation grilles open and letting ventilation systems operate, which helps limit the risk of transmission.
