Which will do the most damage?
Virus infections are very common, and most of them are pretty wimpy. They cause cough, runny nose, and maybe a short case of the runs -- not exactly a fun frolic, but not deadly. The virus infections that cause respiratory symptoms like stuffy nose and cough cause the body to put out a lot of mucous.
Unfortunately, this mucous is like an all-you-can-eat buffet for some bacteria. If mucous builds up in the sinuses, bacteria can creep in, take up shop in there, and cause the infection called sinusitis. In the same way, mucous in the ears can lead to bacterial ear infections, and lung mucous can turn into pneumonia. These bacteria are much worse guests than the viruses, causing pain, fever, and even more serious complications.
It's important to remember that some bacteria and viruses aren’t bad. They wipe their feet and make sure they follow the local customs. Some bacteria even benefit us, and we become sick when they are not present.