H1N1/09 is the virus that is making the rounds. It broke out in 09, and it was a pandemic (meaning it was a brand new strain of virus). It made a lot of people sick, but it killed comparatively few people compared to other virus strains. It is not a pandemic anymore, because most people have an immunity to it. Most victims had complications like COPD, and Asthma, and were very young, or very old.
Influenza attacks the lower respiratory tract. It prefers a temperature of 37 degrees to happily replicate. It will hit you suddenly, it rarely causes vomiting, except in children, it causes major aches and pains, and fever. Fever is the first symptom (although you may feel tired and chilled before that hits) You may get a dry hacking cough.
Rhinovirus (common cold) is a virus that inhabits the upper respiratory tract: nose, ears, eyes, throat. It will survive in temperatures between 32 to 35 degrees...that's why it stays in your head...head cold. It does not like acid environments (drink hot lemon) it does not like elevated, or very low temperatures. (Steam your face). Symptoms begin slowly and include stuffy nose, swollen eyes, sore throat, productive cough with lots of phlegm. You will feel run down, but not as exhausted as with the influenza virus.
Symptoms between the two, Rhinovirus and Influenza, can seem similar, so a really, really bad cold may feel like influenza, and a mild case of influenza might seem like a common cold.
all this information is easily obtained through the health nurse, or your doctor. These viruses spread opportunistically when people are herded together in groups...school, holiday celebrations,summer camps etc...and take advantage of lower standards of hygiene (influenza can stick to a doorknob for quite a while) weather does not seem to affect, or inhibit, their ability to spread.
The human body does not create viruses, but it does produce fevers, and phlegm in an attempt to fry and flood the little buggers out of the body.