Winter changes the odds of exposure
Influenza spreads when an infected person releases virus-containing particles by breathing, talking, coughing, or sneezing. Someone nearby can inhale them, especially in shared indoor air. Cold weather does not produce the virus; it can change the circumstances in which people encounter it.
In winter, people often spend more time together indoors, where ventilation may be limited and particles can accumulate. Cold, dry air may also help influenza spread and can dry the lining of the nose, one of the body’s first barriers against infection. These factors can make transmission easier, but they do not guarantee that anyone will get sick: infection still depends on exposure to influenza virus.
Chills and flu are different clues
Feeling cold or shivering is a response to temperature, not evidence of influenza. Flu symptoms arise after the virus infects the body and the immune system reacts. Other respiratory viruses can cause similar symptoms, so a winter cough or fever is not automatically the flu.
That distinction matters in practice. Warming up can ease discomfort from cold, but it cannot treat an influenza infection; avoiding exposure and vaccination address the virus itself. Winter may create more opportunities for flu to circulate, but the essential link is still a virus passing from an infected person to someone else.
