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Should we get flu vaccinations?

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Here, Dr. Yoichi Sakakihara, Director, Child Research Net, and pediatrician, responds to questions and concerns regarding children's physical well-being and health.


[Question]
Every year I am uncertain about whether my children should be vaccinated against the flu. I hear there are some children who contracted the flu even though they had been vaccinated. If that is the case, is it all right not to have them vaccinated?

[Answer]
The flu is a highly contagious and serious disease that is prevalent every winter. Symptoms include high fever, strong coughing, muscle aches and pains, and headaches. Unlike the common cold, complications such as pneumonia and encephalitis can easily arise, and in the case of young children or the elderly, in particular, it can be fatal. According to the website of the Ministry of Health, Labour and Welfare in Japan, about 10 million people contract influenza each year. During the period from 2001-2005, the reported number of influenza-associated deaths ranged between 214 and 1,818, but the estimated number of deaths is said to be 10,000 per year.

Some may be surprised by the difference between the reported and estimated number of deaths and wonder how this can be explained. In fact, this discrepancy was the major cause of dispute over the justification for vaccination against influenza. Unlike the measles or chicken pox, influenza is not accompanied by any characteristic symptoms, such as a rash, and it is hard to distinguish it from a bad cold or pneumonia. Unless blood tests or rapid test of nose and throat secretion are carried out, it ends up diagnosed as one of these infectious diseases.

Once the influenza vaccine was developed and its efficacy tested, some specialists doubted (and still do) whether the number diagnosed as influenza was actually declining statistically and significantly.

However, it became clear that the number of deaths due to influenza according to the epidemiological method of applying the concept of excess mortality is much higher than the number of deaths due to influenza established by blood tests, etc. In particular, this entailed comparing the number of deaths due to pneumonia in countries (regions) during years when influenza was and was not prevalent. This showed that during years when influenza was prevalent, the number of deaths from pneumonia increased by tens of thousands. In other words, this increase represents the number of deaths due to influenza-pneumonia that were not diagnosed as influenza.

Using this method, the efficacy of the influenza vaccine was verified. As a result, the influenza vaccine was also proven to be effective in decreasing the number of influenza patients.

However, when considered in terms of the rate of preventing infection, the effectiveness of the influenza vaccine is not as high as that of measles vaccine. Two reasons can be cited. Unlike the measles vaccine, which is based on a strain of a live attenuated virus, the influenza vaccine is an inactivated (not a live virus) vaccine. Furthermore, the virus that is prevalent in a particular year will also vary because the influenza virus often mutates genetically from year to year. It is thus necessary to be vaccinated yearly, and vaccination clearly reduces the likelihood of infection.



Note: The respondent of this Q&A series, Dr. Yoichi Sakakihara is a pediatrician practicing in Japan. Please remember to refer to the medical information or conditions of your own country, as the information or ideas contained in this article may not apply to your country.
Neither CRN nor Dr. Sakakihara shall be liable or responsible to any person or entity for any loss or damage caused, or alleged to have been caused, directly or indirectly by the information or ideas contained, suggested, or referenced in these responses.

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Sakakihara_Yoichi.bmp Yoichi Sakakihara
M.D., Ph.D., Vice President, Ochanomizu University; Director of Child Research Net, President of Japanese Society of Child Science. Specializes in pediatric neurology, developmental neurology, in particular, treatment of Attention Deficit Hyperactivity Disorder (ADHD), Asperger's syndrome and other developmental disorders, and neuroscience. Born in 1951. Graduated from the Faculty of Medicine, the University of Tokyo in 1976 and taught as an instructor in the Department of the Pediatrics before assuming current post.
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