Summary We estimated the total number of undiagnosed HBV and HCV carriers and patients with hepatitis virus‐related disease in Japan according to 6 different groups classified by their natural histories during 2011. In 2011, the total number of carriers and patients infected with HBV or HCV was estimated according to 6 groups using government reports and reports from the hepatitis epidemiology research group of The Ministry of Health, Labor and Welfare in Japan. In 2011, the total number of hepatitis virus carriers was estimated to be 2 090 128‐2 840 128 in which the estimated number of undiagnosed HCV and HBV carriers was 776 826 (HBV: 481 470; HCV: 295 356). The total number of treated patients, as either inpatients or outpatients, was estimated to be 811588 (HBV: 303 366; HCV: 520 600) in 2011. It is presumed that many carriers shirk consultation for many reasons, such as patients’ misunderstanding, lack of awareness and forgetfulness of their positive status. The numbers of infected patients who did not seek treatment increased gradually to 501 714‐1 251 714 (HBV: 333 791‐483 791; HCV: 167 923‐767 923) in 2011. Compared to 2000, the number of undiagnosed carriers was significantly reduced in 2011 probably because of the well‐organized, effective national hepatitis virus screening system that has been launched by the Japanese government since 2002. Moreover, the increase in the number of untreated persons who are aware of their positive status shows that more effort should be invested in improving the referral system from screening centres to core hospitals.

Our results showed that operation and blood transfusion were potential risk factors for HBV and HCV infection, respectively, and supposed that horizontal HBV transmission may be frequent in adults in Cambodia. Hence, for reducing HBV and HCV infections, it is necessary to improve the safety of blood and medical treatment.

In Binh Thuan, prevalences of HBV and HCV infections are high, HBV genotype B and HCV genotype 6a are predominant, and horizontal HBV transmission may still occur. Therefore, raising the coverage of a universal HBV vaccination program may be an effective liver cancer control in Vietnam.

Highlights This study proved of Cambodia achieving WHO 2017 target of <1% HBsAg prevalence. HBsAg prevalence in 5–7 years old children was 0.56% (95%CI: 0.32%–0.98%). HBsAg prevalence among the mothers was 4.39% (3.53%–5.45%). Among children with HBsAg-positive mother, prevalence was as high as 10.11%. 78.4% of children received HepB birth-dose and 58.7% were administered ≤24 h.

If the current blood donation behaviors continue, a shortfall of blood availability is likely to occur in Japan. Insufficient blood donations are mainly related to a projected reduction in population of 20 to 30 year olds, a significant group of donors. Thus, it is crucial to recruit and retain new donors and to develop recommendations for proper use of blood products to minimize unnecessary use. This study provides useful information that can be used by governments to help ensure the adequacy of the blood supply through promoting donations and conserving blood resources.