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 For more than a decade, vaccination was mandatory, but the laws were relaxed in 1987 and repealed in 1994; subsequently, vaccination rates dropped to low levels.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.
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.
Authors: Steven A Cohen; Saifuddin Ahmed; Ann C Klassen; Emily M Agree; Thomas A Louis; Elena N Naumova Journal: Vaccine Date: 2010-05-08 Impact factor: 3.641
Authors: Heather E Narciso; Preeti Pathela; Beth Maldin Morgenthau; Susan M Kansagra; Linda May; Allison Scaccia; Jane R Zucker Journal: J Urban Health Date: 2012-04 Impact factor: 3.671
Authors: Nimalan Arinaminpathy; Oliver Ratmann; Katia Koelle; Suzanne L Epstein; Graeme E Price; Cecile Viboud; Mark A Miller; Bryan T Grenfell Journal: Proc Natl Acad Sci U S A Date: 2012-02-07 Impact factor: 11.205
Authors: Susan M Kansagra; Meghan D McGinty; Beth Maldin Morgenthau; Monica L Marquez; Annmarie Rosselli-Fraschilla; Jane R Zucker; Thomas A Farley Journal: Am J Public Health Date: 2011-12-15 Impact factor: 9.308