The H1N1 influenza virus, formerly know as the swine flu, is a serious health concern because it is a new virus that appeared this past spring.

It’s a pandemic because it is worldwide, and because it’s new, no one is immune except for the small number of people who have already had this flu.

This makes it likely that the H1N1 flu will spread quickly and widely this winter. Symptoms are similar to those of the regular seasonal flu. Yet there are reported cases of people who have died from the H1N1 virus.

Those most susceptible seem to be young children and pregnant women. For this reason, the Centers for Disease Control recommend the H1N1 vaccine for pregnant women, children over six months of age, people who care for infants under six months of age, people with underlying medical conditions that affect the heart, lungs or immune system, and people who work in close quarters daily with a lot of people.

People older than 65 may have a mild immunity from a similar virus several decades ago. A seasonal flu vaccine is still recommended for seniors.

For other groups, two separate flu vaccines may be desirable … one for the regular flu and a second for H1N1.