Publications by authors named "Tetsuo Kase"

Article Synopsis
  • Despite the introduction of the rubella vaccine in 1977, rubella and congenital rubella syndrome (CRS) persist in Japan, highlighting flaws in the current immunization strategy.
  • Universal immunization improved vaccine coverage and reduced rubella cases, but outbreaks occurred in 2012-2013 and 2018-2019 due to imported viruses and unvaccinated males.
  • The study suggests that a single-dose vaccination is insufficient to fully prevent infections and CRS, emphasizing the need for a second dose to close immunization gaps and avoid future outbreaks.
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  • The study analyses COVID-19 mortality factors in Osaka, Japan, using data from early 2020 to understand the epidemiological impact of the pandemic and improve public health responses.
  • Among 14,864 patients, 297 died, with higher mortality observed in men, older individuals (especially those over 70), and those with underlying health conditions; mortality rates decreased in subsequent surges.
  • The research highlights key risk factors for COVID-19 mortality, which are critical for future preparedness against emerging infectious diseases.
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To evaluate the antibody response following the initial four doses of mRNA vaccines (BNT162b2 or mRNA-1273) in SARS-CoV-2-naïve healthy adults and investigate factors influencing antibody titer increases, this prospective cohort study was conducted in Japan from March 2021. The study included participants who received either the 1st and 2nd doses (n = 467), 3rd dose (n = 157), or 4th dose (n = 89). Blood samples were collected before and up to 6 months after each dose, and anti-receptor-binding domain antibody levels were measured.

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Background: To evaluate antibody responses against the primary series of vaccination of severe acute respiratory syndrome coronavirus-2 [SARS-CoV-2] vaccines in the staff and residents of Japanese geriatric intermediate care facilities.

Methods: All subjects (159 staff and 96 residents) received two doses of the BNT162b2 mRNA vaccine 3 weeks apart. Baseline data of subject were collected using a structured form.

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  • The study investigated the connection between inactivated influenza vaccination and viral load in children under 6 in Japan over several flu seasons.
  • Researchers analyzed 1,185 influenza-positive children and found that the viral loads did not significantly differ based on vaccination status, with median values around 5.5 for all groups.
  • Key factors impacting viral load included specific influenza subtypes and children's temperature, indicating that vaccination status did not play a role in viral load differences.
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  • The study aimed to understand the incidence and risk factors for norovirus-related diarrhea among elderly residents in Japanese geriatric intermediate care facilities.
  • Conducted from November 2018 to April 2020, the study followed 1,727 residents across 10 facilities, finding that 74 developed diarrhea, with 13 testing positive for norovirus—resulting in an incidence rate of 10.11 per 1000 person-years.
  • Key risk factors for developing norovirus-related diarrhea included a higher care-needs level, hypertension, stroke, and using a cane, indicating a correlation between health conditions and susceptibility to this infection in elderly populations.
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  • - The study assessed the effectiveness of the BNT162b2 mRNA vaccine in generating antibodies in healthy adults through two different immunoassays, highlighting inconsistencies in measurement methods.
  • - Blood samples were taken from 385 healthcare workers at various points: before the first shot, before the second shot, 4 weeks after the second shot, and 6 months later, revealing significant increases in antibody levels after vaccination.
  • - Results indicated that while antibody responses were generally adequate, older participants had lower antibody levels, and the two assays produced different results despite a strong correlation in their findings.
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  • In Japan, the voluntary mumps vaccination program has faced low coverage due to fears of aseptic meningitis as a side effect.
  • A study analyzed adverse event data from over 8 million doses of the Torii strain-derived mumps vaccine, revealing that the overall adverse event rate was 8.33 per 100,000 doses.
  • Notably, the incidence of aseptic meningitis has significantly declined from 7.90 per 100,000 doses in 1998-2000 to 2.78 in 2016-2018, suggesting improvements in the vaccine and diagnosis practices.
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  • This study investigates how prior vaccination affects the effectiveness of the current influenza vaccine in children aged 1-5 years during the 2016/17 and 2017/18 seasons in Japan.
  • The research looked at 799 influenza cases and 1196 controls, categorizing their vaccination status into six groups to analyze vaccine effectiveness (VE). Overall, the effectiveness varied by vaccination history, but one- and two-dose VEs were significant regardless of prior vaccination.
  • The findings suggest that even with prior vaccinations, the current season's vaccines maintain effectiveness, as demonstrated by varying VE percentages among different vaccination groups.
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Background: For the 2017-18 influenza season, A/Saitama/103/2014 (CEXP-002) (Saitama strain) was antigenically more similar to prior circulating strains than A/Hong Kong/4801/2014 (X-263) (Hong Kong strain) in a ferret model and was selected as the A(H3N2) vaccine virus strain in Japan. However, the Saitama strain grew poorly, and the Japanese government switched to the Hong Kong strain, raising public concerns of poor effectiveness. To enhance understanding of the correlation between antigenicity in experimental models and immunogenicity, as a surrogate measure of vaccine effectiveness, in the human population, we compared the immunogenicity of specially-prepared single dose monovalent influenza A(H3N2) vaccines containing the Saitama or the Hong Kong strain.

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  • Pregnant women are prioritized for influenza vaccination, but many hesitate due to concerns about possible negative effects on their fetuses.
  • A study followed over 10,000 pregnant women, comparing those who received the flu vaccine to those who did not, assessing various adverse birth outcomes.
  • The results indicated no increased risk of adverse birth outcomes from vaccination, with a notable decrease in risks during the third trimester for vaccinated women.
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Background: Older adults are vulnerable to hospitalization or death from norovirus infection, but the actual disease burden remains unknown. Therefore, we conducted a nationwide survey to estimate the number of inpatients with norovirus gastroenteritis and associated deaths among Japanese older adults.

Methods: We performed a nationwide two-step query targeting 4184 hospital departments selected from 17,575 departments using stratified random sampling according to the number of beds.

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Background: Severe pediatric cases of hand, foot, and mouth disease (HFMD), herpangina (HA), and associated complications caused by enterovirus 71 (EV71) infection have brought substantial public health impact in Asia. This study aimed to elucidate the epidemiology of these pediatric cases in Japan.

Methods: A nationwide survey was conducted using stratified random sampling of hospital pediatric departments.

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In young children, infrequent antigen exposure, which is partly characterized by fewer vaccinations, may be a factor impairing the immunogenicity of inactivated influenza vaccine.We assessed the effects of prior vaccinations on age-specific immune responses in Japanese children aged 6 months to 3 years, using data from a cohort study with 266 children who had received 2 doses (0.25 mL/dose for < 3 years old, 0.

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Background: Infants <6 months of age are too young to receive influenza vaccine, despite being at high risk for severe influenza-related complications.

Methods: To examine the effectiveness of maternal influenza vaccination in preventing influenza in their infants, we conducted a prospective cohort study of 3441 infants born at participating hospitals before the 2013-2014 influenza season. At the time of recruitment, their mothers completed a questionnaire about influenza vaccination status for the 2013-2014 season.

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A large rubella outbreak occurred in Japan 2013, and 14,344 rubella and 45 congenital rubella syndrome (CRS) cases were reported. At that time, the populational immunity was above the protective threshold assessed by hemmaglutination inhibition (HI) titer. The genotype 2B rubella virus (RV) strains were responsible for the outbreak, which are non-indigenous in Japan.

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Human adenovirus (HAdV) strains isolated from respiratory specimens of 139 children were analyzed to evaluate the endemic situation of HAdV infections in Osaka, Japan, between 2008 and 2015. The cases increased during spring and winter, and the infections were confirmed mainly in children aged ≤ 5 years, comprising 91.9% of the total population examined.

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Introduction: Immunogenicity studies on pandemic influenza vaccine are necessary to inform rapid development and implementation of a vaccine during a pandemic. Thus, strategies for immunogenicity assessment are required.

Objective: To identify essential factors to consider when evaluating the immunogenicity of pandemic influenza vaccines using the experience in Japan with the influenza A(H1N1)pdm09 vaccine.

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Background: An easy and reliable assay for detection of the rubella virus is required to strengthen rubella surveillance. Although a TaqMan RT-PCR assay for detection of the rubella virus has been established in Japan, its utility for diagnostic purposes has not been tested.

Objectives: To allow introduction of the TaqMan RT-PCR into the rubella surveillance system in Japan, the sensitivity of the assay was determined using representative strains for all genotypes and clinical specimens.

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Background: While the immunogenicity and effectiveness of seasonal influenza vaccines among subjects with severe motor and intellectual disability (SMID) are known to be diminished, the efficacy of the A/H1N1pdm vaccine has not been evaluated.

Methods: We prospectively evaluated 103 subjects with SMID (mean age, 41.7 years) who received trivalent inactivated influenza vaccine during the 2010/11 influenza season.

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Background: Using the polymerase chain reaction (PCR) method it is possible to detect uncultivable viruses and discover multiple viral infections. However, the clinical importance of these findings in relation to symptoms is not known.

Objectives: The seasonal fluctuations of respiratory viruses and the clinical outcomes of single infections and dual infections were investigated.

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Unlabelled: Pediatric acute encephalopathy (AE) was sometimes attributed to virus infection. However, viral infection does not always result in AE. The risk factors for developing infantile AE upon virus infection remain to be determined.

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In 2013, a rubella outbreak was observed in Japan, Romania, and Poland. The outbreak in Japan was accompanied by an increase of measles reports, especially from a region where measles is highly controlled. This was attributed to the adult populations affected by this rubella outbreak, similarity of clinical signs between rubella and measles, sufficiently small impact of measles outbreaks from neighboring nations, and elimination levels of measles endemicity.

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Background: Respiratory tract viral infection is one of the most common and important diseases in children. Polymerase chain reaction (PCR) tests are often used to detect viruses in samples, it is difficult to interpret the clinical significance of PCR positivity, which may reflect a past, imminent or active asymptomatic infection due to their high sensitivity. Although single respiratory viruses have been detected in samples from children with symptoms, other respiratory viruses can also be detected simultaneously.

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