To the editor—Kennedy F. Shortridge's News and Views article in the April issue of Nature Medicine1 recalls that influenza has been a significant and highly contagious disease for a long time. It has been estimated that the infamous 1918 epidemic killed about 700,000 Japanese in just a few months. Today, influenza can still lead to death, especially in infants and the elderly, and Japan is seeing too many people succumb to this disease. The fact that most of the deceased have not been vaccinated suggests the need to reevaluate the prophylactic measures that exist for managing influenza in Japan.

The rate of influenza vaccination has been declining in Japan (see Fig.). In the early 1980s, the rate of vaccination in school children was about 80%. By 1992, this figure had dropped to 18% (ref. 2). Moreover, a 1994 amendment of the prophylactic vaccination law which made it no longer compulsory to receive this vaccine, has resulted in a further drop to less than 10%. The same trend can be seen among elderly patients.

Figure 1: Number of subjects using influenza vaccine per 1,000 people in Japan between 1978 and 1997.
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The pre-1994 values were calculated from the numbers of subjects who received influenza vaccinations twice, which has been the formal method in Japan. The post-1994 values were estimated from the numbers of doses produced per 1,000 population because information on the actual vaccination was not available.

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The drop in vaccination rates has been accompanied by skepticism about the effectiveness of prophylactic vaccination for influenza, in part because of poorly designed studies3. As a result, the annual production of vaccine, which peaked at 26,216 liters in 1967, dropped to only 596 liters in 1996.

To promote anti-influenza vaccinations, the health authorities seem to be considering revision of the wording from "arbitrary vaccination" to "official recommendation of vaccination" when the prophylactic vaccination law is reviewed next fiscal year4. Japan's system for the mass production of vaccine must be reviewed accordingly. The dramatic decline in vaccine demand has almost eliminated domestic farm production of hen eggs for vaccine production. To restore social protection against influenza, the nation's authorities will have to rebuild the vaccine mass production system, in addition to obtaining the public trust on the efficacy of vaccination.