Yes living in a cold house is bad for you and your health and can lead to things such as Pneumonia.
People who live in colder houses who keep their heat really low or have no heat at all can freeze to death or at least get hypothermia or Pneumonia.
There are many people out there who can barely afford to eat and so they keep their heat on very low or sometimes leave it off entirely and just bundle up.
That is not good because you can get sick from being in the cold house and your blood pressure can lower as well which is not healthy.
Try to keep your house temperature in the winter to at least 65 F but the higher the better.
I cannot let my house temperature get down to 65 F in the winter or I feel too cold so I keep the temperature in my house to 80 F or at least 70 F to stay warm.
While gone I turn down the heating thermostat to 55 F to keep the pipes from freezing and then I turn it back up when I get home.