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Updated: Aug 27, 2025
Author Spotlight: Advancements and Challenges in Hepatitis B Virus Detection
Published on: December 15, 2023
Trends of hepatitis B virus genotype distribution in chronic hepatitis B patients in Japan
Kazumasa Sakamoto1, Kiyoaki Ito2, Hiroshi Yotsuyanagi3,4
1Department of Gastroenterology, Aichi Medical University, 1-1, Yazakokarimata, Nagakute, Aichi, 480-1195, Japan.
Insights
Hepatitis B virus (HBV) genotype distribution in Japan shows shifting trends. Genotypes B and C are peaking in older adults, while genotype A is increasing in younger individuals.
Area of Science:
- Hepatology
- Virology
- Epidemiology
Background:
- Hepatitis B virus (HBV) causes chronic hepatitis B (CHB), a prevalent global infection.
- Genotypes B and C are dominant in Japan, but genotype A prevalence has shown a gradual increase.
- Nationwide data is needed to understand current HBV genotype distribution trends in Japan.
Purpose of the Study:
- To investigate the nationwide trends of HBV genotype distribution in chronic hepatitis B patients in Japan.
- To compare the distribution of HBV genotypes across different age groups over time.
- To establish a baseline for assessing the impact of universal HBV vaccination on genotype prevalence.
Main Methods:
- A nationwide survey of 4421 CHB patients recruited between 2015 and 2016.
- Comparison of clinical characteristics and genotype distribution with data from 2000-2001, 2005-2006, and 2010-2011.
- Analysis of HBV genotype percentages (A, B, C, D) and age-specific distribution.
Main Results:
- Genotype distribution: A (4.0%), B (16.2%), C (79.1%), D (0.7%).
- CHB with genotype A increased in young adults, despite no overall change in its prevalence.
- Peak distribution for genotypes B and C shifted to older age groups.
Conclusions:
- In Japan, CHB genotypes B and C show a trend towards older age groups, while genotype A is expanding in younger populations.
- These pre-vaccination data are crucial for future studies on the impact of universal HBV vaccination on genotype epidemiology.
- Understanding these shifts is vital for public health strategies and HBV control in Japan.
Background:
Hepatitis B virus (HBV) is one of the most prevalent chronic viral infections that causes chronic hepatitis B (CHB). In Japan, genotypes B and C account for most of acute and chronic cases of hepatitis. However, previous studies showed that the prevalence of genotype A in CHB gradually increased every 5 years. Therefore, we have conducted a nationwide survey to comprehensively investigate the trends of HBV genotype distribution in CHB patients in Japan.
Methods:
4421 CHB patients were recruited between 2015 and 2016. Clinical characteristics and distribution of CHB patients among different age groups and genotypes in 2015-2016 was compared with those in 2000-2001, 2005-2006, and 2010-2011.
Results:
The percentages of genotype A, B, C, and D were 4.0, 16.2, 79.1, and 0.7%, respectively. While the overall percentage of CHB patients with genotype A did not change in the past 5 years, CHB with genotype A increased in young adults. On the other hand, the peak distribution of CHB with genotypes B and C, two genotypes with the largest patient population, has shifted to an older age group.
Conclusions:
In Japan, the peak distribution for CHB with genotypes B and C advanced to an older age group while CHB with genotype A expanded in a younger age group. Given the universal HBV vaccination launch in Japan in 2016, these pre-vaccination survey data provide important baseline information for comparative studies of the impact of universal vaccination on HBV genotypes.
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