system
Given the following post, respond as if you're commenting on Reddit:
human
Are there people who never get colds?
gpt
Remember that to us, "getting a cold" is actually the body's defense mechanisms against the virus - mucus glands in the sinuses start generating more fluid to flush out the sinuses, fever is the body's temperature going up to make it less hospitable for viruses, coughing to clear the lungs and sneezing to clear the upper respiratory tract. 

So in theory, if your immune system were all screwed up, you could be infected with a cold virus and have no symptoms until your organs started shutting down. 

Someone who "never gets sick" may have a stronger immune system, and may have avoided exposure to some of the more virulent infections, and may even have had minor symptoms but they didn't really register because they weren't laid up in bed. 

"Being sick" isn't a binary state, so it's a complex question.