Image “Cold?” courtesy of Allan Foster on Flickr

When you ride the subway in fall, you’re reminded that this is the time of year when people share an invisible gift called The Cold.

There are hundreds of viruses that cause the common cold. All of them have one thing in common, which is that they are good at spreading.

The common cold is relatively harmless from a health perspective. Its impact is cumulative. Millions of people get a cold each year. A cold influences productivity and sociability. The true costs of a cold in most cases are social and economic, not physiological or epidemiological.

Every year, millions of small differences make one big difference. The cold season ends, and the gift exchange attenuates. In the meantime, the common cold feeds the medication industry and accounts for almost half of all the hours spent at home, away from work.

Cold viruses have the simplest of business models. Always be on the move, always adapt, and replicate over and over across a large population.

An idea has “gone viral” when it has met these conditions. It need only have a small, temporary impact on any one individual. If it has the ability to always be on the move, and to adapt across populations and cultures, it will have a cumulative impact.

Make your ideas simple, adaptable, and easy to share. Win over the individual but also consider the cumulative impact of your efforts.