Flu Vaccine Only Mildly Effective in Elderly

Second study found growing resistance to antivirals, especially in Asia

WEDNESDAY, Sept. 21, 2005 (HealthDay News) -- The flu vaccine, a cornerstone of public health policy, is only mildly effective in the population for which it is supposedly most critical: the elderly.

According to a study appearing in the Sept. 22 online issue of The Lancet, vaccines against influenza are only "modestly effective" in people in long-term care facilities and even less effective for elderly people still living in the community.

That research is twinned with another flu study, which found more bad news: that resistance to drugs used to treat influenza has risen 12 percent in the past decade.

This finding, the authors stated, raises questions about the government's policy of stockpiling such drugs.

Strong opinions to the vaccine study came from all sides of the issue.

"The vaccine doesn't work very well at all," said study author Dr. Tom Jefferson, an epidemiologist with the Cochrane Vaccines Field in Rome. "Vaccines are being used as an ideological weapon. What you see every year as the flu is caused by 200 or 300 different agents with a vaccine against two of them. That is simply nonsense."

Dr. Marc Siegel, author of False Alarm: The Truth About the Epidemic of Fear, agreed. "We have set up a situation where a fear is created, and then we try to create the treatment for this fear. The public gets the idea that the flu is going to kill them and the vaccine will save them. Neither is true," he said. "The flu vaccine has use in cutting down on deaths from complications in the chronically ill and people at great risk, but it's not a panacea."

The U.S. Centers for Disease Control and Prevention responded strongly on the other side.

"We certainly do hope that people will not be sidetracked from this important point. There are studies that show that the vaccine is effective in preventing serious complications of the flu," said CDC spokesman Tom Skinner. "This is not going to change the fact that we each and every year recommend people in high-risk categories to get the vaccine."

Health officials worldwide, including those at the CDC, push to get as many elderly individuals as possible vaccinated against the flu each year. According to the study, in 2000, 40 of 51 developed or rapidly developing countries recommended vaccines for all individuals aged 60 and older. In 2003, 290 million doses of vaccine were distributed worldwide.

Earlier this month, U.S. health officials started urging all eligible persons to get a flu shot, with priority given to the elderly and certain other groups. And to avoid last year's flu vaccine shortage, U.S. health officials have planned for a total of 97 million doses of vaccine.

The current study provided no new data but, rather, looked at 64 existing studies which looked at the effectiveness of the flu vaccine over 96 flu seasons.

For elderly people living in the community, inactivated influenza vaccines prevented up to 30 percent of hospitalizations for pneumonia but were not effective against the flu, flu-like illnesses or pneumonia. "The vaccines didn't seem to prevent influenza," Jefferson said.

For elderly people living in long-term care facilities, the picture was slightly brighter, with vaccines preventing up to 42 percent of deaths caused by influenza and pneumonia only.

"We have to concentrate our resources elsewhere or invest in better vaccines," Jefferson stated.

The authors of the second study screened 7,000 influenza A isolates for gene mutations known to confer drug resistance to the antivirals amantadine and rimantadine.

Overall drug resistance increased from 0.4 percent in 1994-95 to 12.3 percent in 2003-04. Also, 61 percent of resistant viruses isolated since 2003 were from people in Asia. Some Asian countries had drug resistance frequencies exceeding 70 percent, possibly a reflection of different prescribing practices.

Strikingly, more than 84 percent of all resistant viruses during the 10-year period under question were identified since the 2003 flu season.

This highlights the importance of continuing to expand surveillance of the emergence of resistance to these drugs, said Rick Bright, lead author of the study and a research scientist with the CDC.

"This is a warning that overuse of antiviral drugs leads to resistance," Siegel said. "The drugs should be specifically used for influenza that is a problem in terms of duration and possible risk of death, not for everybody."

The study authors voiced concern that rising rates of resistance will render amantadine and rimantadine ineffective for treatment or prevention in the event of an influenza pandemic. That, in turn, would render government stockpiles useless.

"I question stockpiling these drugs. You're going to have to discard or overuse them. It's sending a message to the public that these are lifesaving drugs," Siegel said. "Antivirals should be considered in high-risk cases," but in other cases they may only be of limited effectiveness, he said.

"We have to differentiate between potential risk and something that clearly is in the offing. Fear is a warning system that is supposed to protect us against imminent danger such as a gorilla hanging over us," he added. "I want to know why more effort isn't put on getting our vaccination method up-to-date instead of stockpiling millions of doses of vaccine and sending a fear message. We need to see reality."

More information

The National Institute of Allergy and Infectious Diseases has a fact sheet on the flu.

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