People are freaked out about the flu. Public health officials have been fretting about bird flu and the possibility that it could turn into a worldwide pandemic.
There is not much anybody can do about avian flu. No vaccine has been developed, and there is not enough antiviral flu medicine to treat everyone. No one even knows yet whether the bird flu will actually morph into a real danger or if it will just remain a threatening prospect.
In the meantime, public health pundits are urging high-risk Americans to sign up for their annual flu shots. Last year, shortages of flu vaccine created panic as people waited in long lines, only to have supplies run out.
This year experts do not expect a shortfall of flu vaccine. But the heavy emphasis on immunization does not fit well with research on the efficacy of flu vaccine, especially for older, sicker people. Although policy makers pay homage to the concept of evidence-based medicine, the scientific basis for influenza immunization is not that impressive.
Two years ago, for example, the flu shot protected nearly half the healthy adults who got it. But only 38 percent of those at high risk because of chronic illness were protected by the immunization. This was due in part to the fact that the vaccine that year was not a close match for the dominant strain of influenza.
But even in years when the vaccine matches the various types of flu virus circulating in the community, immunization for the elderly may not be as effective as most people think. A study of mortality records for the past three decades shows that death rates from the flu among older people has not changed much during that time. Over the same period, there was a dramatic increase in the rate of flu vaccination, from 15 percent to 65 percent. The investigators concluded that flu shots do not protect this vulnerable population particularly well (Archives of Internal Medicine, Feb. 14, 2005).
A systematic review of many studies of flu vaccine effectiveness suggests that vaccinating elderly people in nursing homes is about 23 percent effective in protecting them from flu-like illness (Lancet, Oct. 1, 2005). According to the researchers, “In elderly individuals living in the community, vaccines were not significantly effective against influenza, influenza-like illness, or pneumonia.”
Of course, this does not mean older people should skip their annual flu shots. But it does mean that we need better data–or better vaccines.
In the meantime, people may want to talk to their physicians about antiviral medications. According to the Centers for Disease Control and Prevention, old-fashioned drugs such as amantadine and rimantadine “are approximately 70 percent to 90 percent effective in preventing symptoms of influenza A illness.”
Newer flu medicines have fewer side effects and work against type B as well as type A flu. These drugs, Tamiflu and Relenza, are the only drugs also proven to fend off bird flu.
Let’s hope that this virus does not mutate and create a worldwide pandemic this winter. There’s still no vaccine to protect people against this disease and even if there were, it would take many months to make enough for everyone.
