Viruses spread through tiny droplets in the air that are released when a sick person sneezes, coughs, or blows their nose. You can get sick if you touch your nose, eyes, or mouth after you have touched something contaminated by the virus, such as a toy, countertop, or doorknob.
Why do we get sick?
Quick summary: your immune system releases cytokines, which release prostaglandins, which trigger the hypothalamus to get you to start behaving in a certain way. Your immune system creates sickness behaviors and sensations, not the illness itself.
How do we get sick in the cold?
Low temperatures can increase the likelihood of getting sick. The body is not as effective at fighting a virus when cold air enters the nose and upper airways, so viruses such as the common cold, the flu and COVID-19 often spread more easily in the winter.