Why have scientists still not found a cure for the common cold?

 Immunization would be the ideal solution. However, because there are more than 200 different cold viruses it is impossible to produce a vaccine that would protect against all types. There are some agents, including the immune system messenger interferon, which stop viruses multiplying, but treatment with these can cause side effects that are worse than the cold itself. New medications are currently being developed, but in order to succeed they will have to be inexpensive, and will need to cure the cold more quickly than it would cure itself by simply being allowed to run its course.