March 2005


Flu vaccines provide virtually no benefit to children. That's the conclusion of a new review of all relevant studies. Interestingly, the news comes at a time when some health officials have begun to recommend the vaccination of all children in order to prevent them from passing on the flu to their elderly relatives. The review follows on the heels of a study that looked at three decades' worth of data and found that vaccines for the elderly are not as effective as previously thought. And contrary to conventional medical wisdom, vaccines do not seem to reduce flu-related deaths in elderly people.

To determine the value of flu vaccines to children, Tom Jefferson, MD, and colleagues at the Cochrane Collaboration looked at over a thousand studies. They selected 14 high-quality clinical trials in which vaccinated children had been compared with unvaccinated children. The combined results of these 14 trials were reported in the British journal The Lancet (2/26/05). Here's the conclusion: “We recorded no convincing evidence that vaccines can reduce mortality, [hospital] admissions, serious complications, and community transmission of influenza.”

The best the Cochrane reviewers could come up was this: “Vaccines were somewhat effective at reducing school absence…” Though the U.S. Centers for Disease Control (CDC) and Prevention advises flu vaccines for babies 6-23 months because they tend to suffer more complications once they get the flu, no evidence supports the recommendation. The Cochrane reviewers found that vaccines had little effect on bronchitis, ear infections, and hospitalizations, compared with the babies given placebo vaccines. In short, the CDC recommendations are irresponsible given the fact that the only two studies that involved babies found no benefit and little is known about adverse effects of these vaccines for babies.

Benefit to Elderly overrated

Now for the importance of flu vaccines to the elderly. A new comprehensive study cast doubt on the widespread belief that flu vaccines save lives (Archives of Internal Medicine, 2/14/05). Though the authors work for a federal government health agency, they produced evidence that failed to support CDC recommendations.

Lone Simonsen, PhD, and colleagues at the National Institute of Allergy and Infectious Diseases conducted a review of 33 consecutive flu seasons, from 1968 to 2001. The authors began their report with an acknowledgement that an accurate assessment of flu-related deaths is virtually impossible because few cases are confirmed with blood tests. And the viral infection is usually cleared from the body before the appearance of complications that cause death. For these reasons, the authors had to use a special statistical method to estimate flu-related deaths and deaths from all causes among elderly Americans over the three-decade-period.

Here is what Dr. Simonsen and colleagues found:

-The number of flu-related deaths among elderly Americans increased steadily during the 33-year-period, despite the fact that their acceptance of flu vaccinations also steadily increased. For example, only 20% of all elderly Americans had a flu shot in 1980, compared with 65% in 2001.

-There was a decline in flu-related deaths among people 65-74 years in the decade after the 1968 flu pandemic because people had naturally acquired immunity due to exposure to the emerging viruses of that period. The increasing flu vaccine coverage after 1980, however, did not correlate with a decline in flu-related deaths.

-The over-all death rate for people over 85 during flu seasons did not change over the 33-year-period. Dr. Simonsen and colleagues cite earlier research that might provide an explanation for why flu vaccines did not reduce the flu-related deaths in “the very elderly” after 1980 when vaccine coverage began to increase, “...antibody responses following influenza vaccination decline sharply after age 65 years and a clinical trial involving subjects 60 years or older...found that the efficacy of influenza vaccine in preventing influenza illness was lower in people older than 70 years.”

Because fewer than 10% of all winter deaths can be attributed to the flu in any year during this study's three-decade period, the authors conclude that vaccination's benefit to elderly people has been substantially overestimated.

Maryann Napoli, Center for Medical Consumers (C) March 2005.