Germs are around us all year so winter itself, is not the root cause of certain sicknesses, but it increases their causing factors. For instance, due to the freeze of the cold people tend to stay indoors which increases the person to person contact in closed places. Hence, provides a mean for readily spreading of viruses. In winter people tend to become less active, as they avoid
outside activities which consequently weakens their immune system and makes them more vulnerable to sicknesses.

Winter sicknesses spread around in the form of germs and viruses which ultimately lead to winter bugs such as flu and cold. No matter where you reside in the world, there is an even chance of catching the Norwalk virus and the illness that follows it. Another common winter sickness is the viral gastroenteritis, usually called the stomach flu or the undesirable term vomiting disease. Regardless of any label, this disease is highly contagious, difficult to kill and to suppress. Moreover, this bug can be found almost everywhere.

Winter sicknesses can also be caused by a vitamin D deficiency. It is currently being investigated that can a deficiency in vitamin D slows down the immune system and make it more vulnerable to winter diseases than cold and wet tissues.
Preventative care practice against winter sicknesses results in the build up of resistance against common winter sicknesses. Practice of proper basic hygiene reduces the contagiousness of illnesses. The most suitable way of reducing the risk of illness is the vigorous washing of hands for a minimum time period of twenty seconds with antibacterial soap. Avoid touching the face with hands as the eyes and nasal cavities are the foremost direct routes of catching a virus or bacteria. Whenever possible, avoidance of exposure to germs and viruses is another way to shield oneself against pesky winter diseases.