Update on the 2005-2006 Influenza Season

October 4, 2005

"There is some drama associated with influenza every year," said George Kent, MD, associate director of the Center for Education in Family and Community Medicine at the Stanford University School of Medicine. "In 2004, it was the surprise vaccine shortage and the surge in demand, followed by a very ordinary year in terms of disease. This year, we appear to have plenty of vaccine, except for avian influenza, for which we have no vaccine at all."

"There is some drama associated with influenza every year," said George Kent, MD, associate director of the Center for Education in Family and Community Medicine at the Stanford University School of Medicine. "In 2004, it was the surprise vaccine shortage and the surge in demand, followed by a very ordinary year in terms of disease. This year, we appear to have plenty of vaccine, except for avian influenza, for which we have no vaccine at all."

How the current flu season will close next spring is anybody's guess, Dr. Kent told a noontime session at the American Academy of Family Physicians Scientific Assembly. Although the Centers for Disease Control and Prevention expects about 96 million doses of vaccine, the agency created its first tiered vaccination schedule in case last year's shortage reappears.

Physicians and other health care workers are in the tier slated for first access to vaccination. Other Tier 1 groups include individuals aged 65 and older, residents of nursing homes an other long term care facilities, adults and children over 6 months old with chronic heart or lung conditions, women who will be pregnant during flu season, infants aged 6 to 24 months, adults aged 50 to 64, plus caregivers and close contacts of high risk adults or children.

Starting October 24, vaccination is open to anyone who desires protection. The only contraindications are severe allergy to chicken eggs, severe allergic reaction to prior influenza vaccination or presentation with Guillain-Barré syndrome (GBS) within six weeks of prior flu vaccination, infants under six months of age, and those with a moderate to severe illness with fever.

"I always tell patients that flu vaccine is not designed to keep them from getting flu," Dr. Kent said. "I tell them that the vaccine is intended to keep them out of the hospital and keep them from dying. In a typical year, vaccination reduces influenza mortality by 78%."

The vaccine supply this year includes a live attenuated intranasal produce indicated for healthy individuals aged 5 to 49 and four killed virus intramuscular vaccines indicated for patents older than six months.

Avian influenza remains a question mark. For now, Dr. Kent said, it is largely confined to avian populations in Asia, although sporadic transmission to humans has been reported since 1997. There have also been scattered of human-human transmission. The overall human mortality rate has been about 50%.

"Avian influenza is highly pathogenic and it is a species jump, so there is no human immunity," Dr. Kent explained. "It is not readily contagious between humans yet. This is the best candidate since the Spanish Flu of 1918 for the generation of a pandemic."

A human vaccine against avian influenza is being developed, Dr. Kent said, but remains in testing. Computer modeling suggests that a pandemic can develop in about six months, he continued, and vaccine production takes about 100 days. If a human outbreak occurs, vaccine will be available in extremely limited quantities if it is available at all.

Enforced quarantine of victims and their contacts is likely, he added and family physicians will probably be called upon to enforce quarantine conditions.