A cold is a viral infection of the upper respiratory tract. It can occur throughout the year. We most often encounter it in winter, as some respiratory viruses multiply best in cold environments.

We catch a cold when our immunity is weakened and a sufficiently aggressive virus enters the respiratory tract in a sufficient quantity. This means that several factors favoring the viruses must be present simultaneously.

If our immunity is good, even the entry of a virus into the respiratory tract does not trigger illness. The immune system destroys the virus before it can multiply and cause inflammation. That is why it is so important to take care of our health and thus maintain good immunity.