Expert answer

A person who gets a specific influenza and recovers generally has immunity to that specific virus for some period, usually a decade or two. After time the immune system may have a lapse in memory and the person can get re-infected. A very few individuals with compromised immune systems may be susceptible to it earlier.

Some viruses have been known to mutate or change just enough that people who had the virus just a short time earlier technically can be re-infected with the mutated or changed virus. We are still learning about the H1N1 and do not know if it will change so quickly.

This is a long-winded way of saying everyone should be vigilant. Even if you have had the H1N1, you should practice flu prevention. There are other germs out there that can be easily spread to include the seasonal flu. Wash hands frequently, and cough or sneeze into the upper arm. If sick with a fever or flu-like symptoms, stay home. Do not go to work or school if sick. Most flu viruses are spread when people start congregating indoors.