Introduction The BNT162b2 and mRNA-1273 COVID-19 vaccines are the main vaccines that have been used for mass vaccination in Japan. Information on adverse reactions to COVID-19 vaccines in the Japanese population is limited. Methods We conducted an online survey on self-reported adverse reactions in individuals who had received two doses of the BNT162b2 mRNA or mRNA-1273 vaccine. The incidence of adverse events after each dose of vaccine was investigated. Propensity score matching was used to compare the incidence of adverse reactions after the second dose of the BNT162b2 mRNA and mRNA-1273 vaccines. Results After the first and second doses of the BNT162b2 vaccine, and the first and second doses of the mRNA-1273 vaccine, 890, 853, 6401, and 3965 individuals, respectively, provided complete responses. Systemic reactions, including fever, fatigue, headache, muscle/joint pain, and nausea were significantly more common in females, individuals aged <50 years, and after the second dose. The incidence of injection site pain did not differ significantly according to the dose. The incidence of delayed injection site reactions after the first dose of mRNA-1273 vaccine was 3.9% and 0.8% among females and males, respectively, and 10.6% among females aged 30–69 years. Local and systemic reactions after the second dose, including fever, fatigue, headache, muscle/joint pain, nausea, and skin rash were more common in individuals who had received the mRNA-1273 vaccine. Conclusions Adverse reactions were more frequently reported in females, younger individuals, and after the mRNA-1273 vaccine.

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BACKGROUND: The classification of many new cases of hepatitis virus infection as overt hepatitis does not reflect the true incidence of infection because the disease takes an asymptomatic course in some cases. In this retrospective cohort study, we aimed to estimate the incidence rates of new hepatitis C virus (HCV) infections among the blood donors. STUDY DESIGN AND METHOD: A 5-yearretrospective cohort study was conducted to estimate the incidence rates by using the medical records of the blood donors between 2008 and 2013 for HCV infection. HCV seroconversions were investigated using a chemiluminescent enzyme immunoassay and then confirmed by nucleic acid amplification tests. RESULTS:The incidence rate of HCV infection was 0.40 per 100,000 person-years (95% confidence interval, 0.27-0.57) for HCV RNA seroconversion only and 7.32 per 100,000 person-years (95% confidence interval, 6.73-7.95) if either HCV RNA or anti-HCV seroconversion were taken into consideration. No significant difference of new HCV infections was found between the sexes. CONCLUSION:The incidence rate of HCV infection of this study was lower than that detected in a previous 1994-2004 study in which HCV incidence was 1.86 per 100,000 person-year, which reflects the presence of an effective blood screening system and health strategies targeting hepatitis control and prevention.ABBREVIATIONS: CI = confidence interval; HCV = hepatitis C virus; JRC = Japanese Red Cross; NAAT = nucleic acid amplification testing.From the

Background Long‐term prognosis of patients with chronic hepatitis C infection (HCV) remains incompletely characterized. We investigated the long‐term prognosis of liver disease in patients with chronic HCV infection who have not received antiviral therapy. Methods A total of 2304 patients with chronic HCV who were not received interferon‐based therapy were included. Results In the assessment of 1‐year disease state of liver transition probabilities, progression to chronic hepatitis occurred in 12% to 14% of patients across all age groups in male asymptomatic carriers. In male patients with chronic hepatitis, progression to cirrhosis was observed mostly in the 60 to 69 (7.6%) and ≥70 age groups (9.6%). In addition, in male patients with cirrhosis, HCC development occurred in approximately 5% of patients over the age of 40. In female asymptomatic carriers, progression to chronic hepatitis was observed in 6% to 14% of patients across all age groups. In female patients with chronic hepatitis, progression to cirrhosis was observed mostly in the 60 to 69 (8.7%) and ≥70 (7.4%) age groups. In addition, in female patients with cirrhosis, HCC development occurred in 0.9% to 3.3% of patients over the age of 50. Under assumptions of either chronic hepatitis or asymptomatic carrier state at age 40 as the starting condition for simulation over the following 40 years, the probability of HCC gradually increased with age and was higher in male patients. Conclusions There is a risk of cirrhosis or HCC development in HCV patients with not only chronic hepatitis but the asymptomatic carrier state as well.

Background & Aims:The relationship between the frequency of drinking and fatty liver in the general population is still poorly understood. This study analysed data from a large cohort who underwent health checkups in Japan between 2008 and 2019 to investigate the prevalence and incidence of fatty liver by alcohol consumption and risk factors for fatty liver. Methods:The prevalence of fatty liver diagnosed with ultrasonography was calculated in 75,670 residents. The incidence of fatty liver in 31,062 residents who underwent ultrasonography at least twice during the period without fatty liver at the first time was calculated using the person-year method. Multivariate logistic analysis was performed to investigate risk factors associated with the prevalence and incidence of fatty liver.