There is substantial evidence that school closures decrease the number of people infected with influenza. So, it is not surprising that a new study from Japan demonstrates the striking effect of this variable on the number of deaths from pandemic H1N1 in Japan and the United States. In my recent blog on the Incidence of death for 2009, I reported an incidence of death per 100,000 people of 0.9 for the United States and 0.1 for Japan. The authors sought to explain the strikingly low number of deaths found in Japan with respect to other countries, including the United States.
In Japan, Tamiflu is prescribed quite readily, even for seasonal flu. So, this may be one possible factor in the lower mortality there than in other countries. However, the authors of the Japanese study also found that many fewer young people became ill with influenza in Japan as compared to other countries. There is one obvious possible explanation – more extensive use of school closures in Japan. From the study:
In the previous section, we showed that the epidemiological characteristics of pandemic H1N1 are unique in Japan, which may have kept the CFR low. The main question arises: why are there unique epidemiological characteristics in Japan? The majority of cases have occurred in age groups of 5–9 years and 10–14 years (Figure 1). In general, children in primary school are aged between 6 and 12 years, and those in junior high school are aged between 13 and 15 years. Therefore, the current age distribution of cases indicates that the majority of pandemic H1N1 cases in Japan have occurred among children in primary and junior high schools. Both pandemic and seasonal influenza outbreaks often start as school outbreaks, which often become a trigger for community outbreaks. This is why early school closures or suspension of classes can be effective in reducing transmission into the community. In Japan, suspension of classes is commonly implemented even for seasonal influenza. For example, during the 2006–7 influenza season, 14,103 institutions (including day care centers, kindergartens and primary, junior high, and high schools) suspended classes. An even more aggressive suspension of class policy has been implemented for pandemic H1N1 in 2009. Between October 25 and December 5, 2009, 94,781 institutions had implemented suspension of classes. On the other hand, the CDC of the United States is not recommending such aggressive measures in the school setting.
Recent reports in the media quote American public health authorities congratulating themselves for their excellent handling of the pandemic. I find this puzzling considering that the United States has one of the highest numbers of deaths, adjusted for population, in the world. We are in the top 10% of deaths per 100,000. Hence, by objective measures, the CDC has done a terrible job.
Policies have consequences. The consequence of Thomas Frieden’s decision to keep the schools open was 9 times more deaths in the United States, including hundreds of children, than in Japan.
Thomas Frieden and the US public health establishment have nothing to be proud of.
Kamigaki and Oshitani (2009) Epidemiological characteristics and low case fatality rate of pandemic (H1N1) 2009 in Japan. PLoS Currents: Influenza.