The various viral infections of the respiratory tract referred to as colds, and their complications, are responsible for much discomfort and disability, including work absenteeism and vast expenditures for drugs and medical services.
Colds are responsible for more lost work days than any other viral infection. On average adults have two colds a year and children five or six. And it occurs in wet and cold weather. People with impaired or weak immunity systems, such as people with AIDS, the very young and the very old are at particular risk. Smokers tend to get more frequent and severe colds as a result of damaged lungs. Babies may be at risk of death because their narrow airways are easily plugged by secretions pouring out in response to infection. Introverted people have more colds and spread more viruses when they are infectious. As an indication, the market for cold remedies (including inhalants and rubs) in the UK in 1986 was £34 million.