Why is it that people get sick around the holidays?

Holiday times are notorious for spreading germs due to close contact like hugs and kisses, or even shaking hands.

.. and I believe there is now claims that holidays are cause for higher than average illnesses due to increased sugar intake thanks to all the goodies people eat around that time

Massive crowds of people indoors in close proximity, creating an environment where germs stick to surfaces.  Vitamin D, which helps build the immune system, may be lower due to less sunlight. The laws of thermodynamics, means cold air can carry less water vapour before it reaches the “dew point” and falls as rain. So while the weather outside may seem wetter, the air itself is drier as it loses the moisture. These dry conditions seem to offer the perfect environment for the flu virus to flourish. Any time we splutter with a cold, we expel a mist of particles from our nose and mouths. In moist air, these particles may remain relatively large, and drop to the floor. But in dry air, they break up into smaller pieces eventually becoming so small that they can stay aloft for hours or days. Hence, you could be breathing in a cocktail of viruses at anyone time.

It's because usually when there's more people in confined area, not everyone is taking the proper procautions like washing their hands,  or covering their mouth when they cough or sneeze.

Everyone has such wonderful answers. I would like to add that during the holidays people are under way more stress then usual so their defense system is lowered. And people tend to get the blues so that causes an immune system to lower as well.

It's not that. It's that some of us get sick of all of the ^&*holes.

Because disease doesn't discriminate