Longitudinal epidemiological studies to clarify the difference in effectiveness of countermeasures against influenza in different age groups

Abstract

Uchida and the research team are working to clarify the differences in influenza epidemics in different age groups, with a view to more effectively preventing and treating outbreaks; thereby filling a gap in the research landscape. Their research is specifically targeted to Japan, where influenza poses a problem: ?In Japan, influenza is prevalent almost every winter," Uchida explains. "Although the exact number of people infected is not clear, the National Institute of Infectious Diseases Japan estimates that more than 10 million people are infected. Influenza not only presents a burden on medical care, it also leads to the problem of increasing the excess death of the elderly and stagnating social economy." Vaccination is an effective preventative measure, ie. pharmaceutical intervention (PI), along with mask wearing and school closure, ie. non-pharmaceutical intervention (NPI). However, evidence of these NPIs is lacking and medical diagnosis and administration of antiviral drugs are required at the early stage of influenza onset, but sometimes it is too late and infection has already begun. Therefore, there is work to be done. Uchida explains why the true effectiveness of current PIs and NPIs has not been evaluated: "Influenza vaccine is sometimes expressed as incomplete. This is because influenza subtypes change every year and their effects are not fully demonstrated if they differ from the type used for vaccination. There are also years when vaccines run short because vaccine production does not keep up with the size of the epidemic," he says. "In addition, the vaccine is about $30 in Japan, so it is not inexpensive. Therefore, citizens who doubt the effect of the influenza vaccine influence the decrease of vaccine coverage and are also becoming part of the cause of epidemic expansion. Furthermore, since the effect of NPI is difficult to quantify, no standard consensus has been obtained and the effect varies depending on the research announcement." It is the team's goal to quantify the effectiveness of PIs and NPIs as much as possible, as they are confident that if this can be done, countering influenza will become easier. To do this, the researchers are using epidemiological methods in their work.