Seasonal flu like to attack with full force. It starts with a rapidly rising fever and chills that soon become accompanied by muscle aches, sore throats and headaches.

However, this year's flu has been unusually restrained so far. According to Mia Brytting, Head of Unit at the Public Health Authority, it is because the immunity to winter's current flu variants is great and that the winter has been mild.

- When it is cold outside, the humidity becomes lower, which makes the virus spread more efficiently. When it is warmer, airborne disease spreads, she says.

Children and young people most vulnerable

Although the spread is slow, the curve points upwards across the country. During week 5, 465 cases of influenza were reported, just over a hundred more than week 4. In particular, the proportion diagnosed with influenza B has not increased to any great extent in recent years. This means an increased risk of becoming ill for children and adolescents who have not yet developed immunity.

- It's getting under way now, but we can't say how intense this year's flu season will be. We will probably reach the peak in late February or early March, says Mia Brytting.

This winter, the flu season seems to have ended in the cloud of the noted corona virus, despite the former affecting many more. In Sweden, only one case of the corona virus has been detected, but spreading it will also affect the spread of the flu, says Mia Brytting.

- Then we would probably be more careful about our hygiene, which would mean that the flu is circulating to a lesser extent. The coronavirus would also activate the immune system of those affected, which would keep the flu away.