The Japanese experience with vaccinating schoolchildren against influenza

Thomas A. Reichert, Lone Simonsen, Norio Sugaya, David S. Fedson, W Paul Glezen, Masato Tashiro

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Abstract

Background Influenza epidemics lead to increased
mortality, principally among elderly persons and others
at high risk, and in most developed countries, influenza-control
efforts focus on the vaccination of this
group. Japan, however, once based its policy for the
control of influenza on the vaccination of schoolchildren.
From 1962 to 1987, most Japanese schoolchildren
were vaccinated against influenza. For more than
a decade, vaccination was mandatory, but the laws
were relaxed in 1987 and repealed in 1994; subsequently,
vaccination rates dropped to low levels. When most
schoolchildren were vaccinated, it is possible that herd
immunity against influenza was achieved in Japan.
If this was the case, both the incidence of influenza
and mortality attributed to influenza should have been
reduced among older persons.
Methods We analyzed the monthly rates of death
from all causes and death attributed to pneumonia and
influenza, as well as census data and statistics on the
rates of vaccination for both Japan and the United
States from 1949 through 1998. For each winter, we
estimated the number of deaths per month in excess
of a base-line level, defined as the average death rate
in November.
Results The excess mortality from pneumonia and
influenza and that from all causes were highly correlated
in each country. In the United States, these rates
were nearly constant over time. With the initiation of
the vaccination program for schoolchildren in Japan,
excess mortality rates dropped from values three to
four times those in the United States to values similar
to those in the United States. The vaccination of
Japanese children prevented about 37,000 to 49,000
deaths per year, or about 1 death for every 420 children
vaccinated. As the vaccination of schoolchildren
was discontinued, the excess mortality rates in Japan
increased.
Conclusions The effect of influenza on mortality is
much greater in Japan than in the United States and
can be measured about equally well in terms of deaths
from all causes and deaths attributed to pneumonia
or influenza. Vaccinating schoolchildren against influenza
provides protection and reduces mortality from
influenza among older persons.
OriginalsprogEngelsk
TidsskriftThe New England Journal of Medicine
Vol/bind344
Udgave nummer12
Antal sider8
ISSN0028-4793
StatusUdgivet - 2001
Udgivet eksterntJa

Citer dette

Reichert, T. A., Simonsen, L., Sugaya, N., Fedson, D. S., Glezen, W. P., & Tashiro, M. (2001). The Japanese experience with vaccinating schoolchildren against influenza. The New England Journal of Medicine, 344(12).