The health ministry will conduct an epidemiologic investigation into whether H1N1 influenza vaccinations can increase the death risk for people with serious chronic diseases, ministry officials said Wednesday.
The Ministry of Health, Labor and Welfare plans to begin the study next spring amid an increasing number of reports of deaths and serious side effects among the people who have received shots of domestically produced vaccines against the virus.
The ministry said postvaccination deaths have totaled 104, roughly 80 percent of whom are people aged 70 or older who had chronic diseases or disorders, while nearly 1,900 cases of side effects had been reported from medical institutions.
It estimates 14.92 million people have been vaccinated so far nationwide.