There are few conditions with a name that includes information on prevalence, but the common cold is one everybody knows of. It is so common that, on average, adults experience two or three colds a year, and children double that.

The common cold is a viral infection of the upper respiratory system. There are over 200 forms of the various viruses that can cause a cold and they are constantly evolving and changing, which explains why a vaccine or cure has not been developed, and also how it comes about that someone can experience a cold even though they have just recovered from one. It is possible, over time, to build immunity to some of the viruses that cause a cold – which is why adults tend to get fewer colds than children.

In most cases, while the symptoms can feel miserable, they are thankfully short-lived, generally passing in a week or two. However, for individuals with compromised immune systems – perhaps because of age (or lack of), but also because of having a long-standing health problem such as asthma or diabetes, or even simply by being a smoker – the initial infection can lead to something more serious such as acute bronchitis and pneumonia.

Did you know?

Someone with a cold is infectious until all their symptoms are gone – usually after a week or two.