Very frequent colds and interferon efficiency

Patient: I have very frequent colds, in autumn and spring I have the flu symptoms 3-4 times every month, i.e. I ‘m sick every week. I feel better but 2-3 days after I have a fever and runny nose again. I don’t think it is normal to catch a cold so often, may be I have something with immune system? Kind of immunodeficiency? Which tests should I make? I live in Russia and here all the doctors prescribe interferon alpha-2a for common cold treatment, they prescribe it even to newborn and pregnant women, they say it is totally safe and I can take interferon every time I feel the flu symptoms, but in Pubmed I read that it is normally used only for hepatitis and cancer treatment and it has a lot of side effects. If it is true, why do they prescribe interferon like a vitamin supplement? Should I take it? Thank you!

Symptoms: Sneezing, runny nose, fever, weakness, light sensitivity

Doctor: