Dr. Bill Elliott: Who'll get swine flu vaccine first?

The H1N1 flu (swine flu) pandemic continues at low levels in the United States, but is expected to pick up in intensity this fall, once schools go back in session. As most are aware, H1N1 is a new virus that is the result of a mutation or "reassortment" of the genetic material of several flu viruses. Most younger people have no natural immunity to the virus and it has spread rapidly worldwide, mostly in people younger than 40, since the first cases were discovered in Mexico just a few months ago.

The Centers for Disease Control and vaccine manufacturers are working diligently on a vaccine, and the CDC reports that it should be available by this fall.

The logistics of the H1N1 vaccine are still unclear. The H1N1 vaccine will be a separate vaccine from the standard flu vaccine that is given every year, so most people will need at least two shots this fall. It is likely that the H1N1 vaccine will not be ready by the time the yearly flu vaccine is available, and it is not clear if they could safely be given together. It is also not clear if the H1N1 vaccine will require two shots or just one to achieve immunity.

What is clear is that are there are some people who will need to get first doses of the vaccine.

Unlike most flu strains, it is younger people who are at highest risk of dying from this virus, so those over 65 years old are the lowest priority for the vaccine. Most older adults have some natural immunity to similar viruses from years ago and seem to get a milder

form of H1N1.

The vaccine will be first given to those who are at highest risk and those who are most likely to spread the disease if they get infected. This includes:

- Pregnant women

- People who live with or care for children younger than 6 months of age

- Health care and emergency services personnel

- Persons between the ages of 6 months through 24 years of age

- People from ages 25 through 64 years who are at higher risk for novel H1N1 because of chronic health disorders or compromised immune systems

The groups listed above total approximately 159 million people or nearly half the population of United States.

There are no current concerns about shortages of the vaccine, but if supplies are limited initially, the priority would be: pregnant women; people who live with or care for children younger than 6 months of age; health care and emergency services personnel with direct patient contact; children 6 months through 4 years of age; and children 5 through 18 years of age who have chronic medical conditions.

Once high-risk patients have been vaccinated, the vaccine distribution will be expanded to everyone, including adults over 65.

Dr. Bill Elliott is assistant physician in chief for Kaiser Permanente's Novato office and Petaluma and an Assistant clinical professor of medicine at UCSF Medical School. His column appears every other Monday.