Molecular Epidemiology of Respiratory Syncytial Virus during 2019-2022 and Surviving Genotypes after the COVID-19 Pandemic in Japan.

To evaluate the changes in respiratory syncytial virus (RSV) collected between 2019 and 2022, we analyzed RSV-A and RSV-B strains from various prefectures in Japan before and after the COVID-19 pandemic. RT-PCR-positive samples collected from children with rapid test positivity at outpatient clinics in 11 prefectures in Japan were sequenced for the ectodomain of the G gene to determine the genotype. Time-aware phylogeographic analyses were performed using the second hypervariable region (HVR) of the G gene from 2012 to 2022. Of 967 samples, 739 (76.4%) were found to be RSV-positive using RT-PCR. RSV peaked in September 2019 but was not detected in 2020, except in Okinawa. Nationwide epidemics occurred with peaks in July 2021 and 2022. The genotype remained the same, ON1 for RSV-A and BA9 for RSV-B during 2019-2022. Phylogeographic analysis of HVR revealed that at least seven clusters of RSV-A had circulated previously but decreased to two clusters after the pandemic, whereas RSV-B had a single monophyletic cluster over the 10 years. Both RSV-A and RSV-B were transferred from Okinawa into other prefectures after the pandemic. The RSV epidemic was suppressed due to pandemic restrictions; however, pre-pandemic genotypes spread nationwide after the pandemic.

Factors associated with viral RNA shedding and evaluation of potential viral infectivity at returning to school in influenza outpatients after treatment with baloxavir marboxil and neuraminidase inhibitors during 2013/2014-2019/2020 seasons in Japan: an observational study.

BACKGROUND: This study assessed the differences in daily virus reduction and the residual infectivity after the recommended home stay period in Japan in patients infected with influenza and treated with baloxavir (BA), laninamivir (LA), oseltamivir (OS), and zanamivir (ZA). METHODS: We conducted an observational study on children and adults at 13 outpatient clinics in 11 prefectures in Japan during seven influenza seasons from 2013/2014 to 2019/2020. Virus samples were collected twice from influenza rapid test-positive patients at the first and second visit 4-5 days after the start of treatment. The viral RNA shedding was quantified using quantitative RT-PCR. Neuraminidase (NA) and polymerase acidic (PA) variant viruses that reduce susceptibility to NA inhibitors and BA, respectively, were screened using RT-PCR and genetic sequencing. Daily estimated viral reduction was evaluated using univariate and multivariate analyses for the factors such as age, treatment, vaccination status, or the emergence of PA or NA variants. The potential infectivity of the viral RNA shedding at the second visit samples was determined using the Receiver Operator Curve based on the positivity of virus isolation. RESULTS: Among 518 patients, 465 (80.0%) and 116 (20.0%) were infected with influenza A (189 with BA, 58 with LA, 181 with OS, 37 with ZA) and influenza B (39 with BA, 10 with LA, 52 with OS, 15 with ZA). The emergence of 21 PA variants in influenza A was detected after BA treatment, but NA variants were not detected after NAIs treatment. Multiple linear regression analysis showed that the daily viral RNA shedding reduction in patients was slower in the two NAIs (OS and LA) than in BA, influenza B infection, aged 0-5 years, or the emergence of PA variants. The residual viral RNA shedding potentially infectious was detected in approximately 10-30% of the patients aged 6-18 years after five days of onset. CONCLUSIONS: Viral clearance differed by age, type of influenza, choice of treatment, and susceptibility to BA. Additionally, the recommended homestay period in Japan seemed insufficient, but reduced viral spread to some extent since most school-age patients became non-infectious after 5 days of onset.

Efficacy of edoxaban for the treatment of gynecological cancer-associated venous thromboembolism: analysis of Japanese real-world data.

OBJECTIVE: Direct oral anticoagulants (DOACs) are increasingly being used for the treatment of cancer-associated venous thromboembolism (CAT). However, there is limited evidence of the efficacy of DOACs for the treatment of gynecological CAT. Thus, this study aimed to investigate the efficacy and safety of edoxaban for the treatment of gynecological CAT using Japanese real-world data. METHODS: We reviewed the medical records of patients with 371 gynecological cancer who received edoxaban or vitamin K antagonist (VKA) between January 2011 and December 2018. RESULTS: Altogether, 211 and 160 patients were treated with edoxaban and VKA, respectively. Fourteen patients (6.8%) in the edoxaban group and 22 (13.8%) in the VKA group showed recurrence of venous thromboembolism (VTE). Cumulative VTE recurrence was not significantly different between the 2 groups (p=0.340). Adverse events occurred in 15 (7.1%) and 11 (6.9%) patients in the edoxaban and VKA groups, respectively (p=0.697). Subgroup analysis of the edoxaban and VKA groups according to different tumor types, including ovarian, endometrial, and cervical cancer, showed equivalent outcomes in terms of VTE recurrence and adverse events. Patients without pulmonary embolism (PE) were mostly omitted from initial unfractionated heparin (UFH) therapy prior to administration of edoxaban. However, this did not increase the recurrence of VTE. CONCLUSION: This study confirmed that edoxaban is effective and safe for the treatment of gynecological CAT. This finding was consistent for different types of gynecological cancer. Additionally, initial UFH therapy prior to the administration of edoxaban may be unnecessary for patients without PE.

Duration of fever and symptoms in influenza-infected children treated with baloxavir marboxil during the 2019-2020 season in Japan and detection of influenza virus with the PA E23K substitution.

Data on the clinical effectiveness of the novel anti-influenza drug baloxavir marboxil (baloxavir) in children remain limited. We conducted an observational study to compare the duration of fever and symptoms between baloxavir- and oseltamivir-treated children infected with influenza A and B. In total, 159 outpatients with influenza A(H1N1)pdm09 or B/Victoria-lineage infections, aged <19 years, during the 2019-2020 influenza season in Japan were enrolled and assessed the duration of fever and symptoms using the Kaplan-Meier method and a multivariate Cox proportional hazard regression model. Polymerase acidic (PA) variants were examined before and after baloxavir treatment. In the multivariable analysis, the duration of fever and symptoms was unaltered between the A(H1N1)pdm09 (n = 116) and B/Victoria-lineage (n = 43) groups. Conversely, the fever duration was marginally longer in the oseltamivir-treated group (n = 59) than in the baloxavir group (n = 100) (hazard ratio (HR) = 0.67, p = 0.05); however, the duration of symptoms was unaltered between the two groups (HR = 0.74, p = 0.11). No patient presented PA reduced susceptibility marker(s) before baloxavir treatment in the analyzed groups. The PA/E23K variant was detected in one case (1.5%, 1/66) of A(H1N1)pdm09 after baloxavir treatment. One case (2.0%, 1/50) of A(H1N1)pdm09 with an N295S substitution in neuraminidase was detected following oseltamivir treatment. These results suggested that the duration of fever was likely to be shorter with baloxavir than with oseltamivir, but the difference between influenza A (H1N1)pdm09 and B/Victoria-lineage was unclear. It is important to continue evaluating the clinical effectiveness of baloxavir and monitoring its drug susceptibility to the influenza virus.

Vaccine acquired pertussis immunity was weakened at 4 years of age and asymptomatic pertussis infection was suspected based on serological surveillance.

Serological surveillance of pertussis antibodies was performed in 118 children aged 1-12 years. The positivity of pertussis toxin (PT) antibodies was low at 4-6 years and significantly higher at 8-9 years, compared with those at 6 years. Fimbriae 2 (Fim2) antibody showed similar response to the PT antibody. Higher antibody titers against Fim3 were observed among subjects ≥5 years and highest at 8 years. Data demonstrated that the vaccine-induced antibodies decayed by 4-5 years and subclinical pertussis infection was suspected thereafter, suggesting the need for additional dose at around 4-5 years.

Seasonal split influenza vaccine induced IgE sensitization against influenza vaccine.

Although anaphylaxis is an extremely rare vaccine-associated adverse event, it occurred in young children following administration of the 2011/12 seasonal split influenza vaccine, which contained 2-phenoxyethanol as the preservative. These children had high levels of IgE antibodies against influenza vaccine components. We herein investigated why these children were sensitized. One hundred and seventeen series of serum samples were obtained immediately before, and one month after the first and second immunizations with the HA split vaccine of 2011/12. Forty-two sequential serum samples were collected in the acute and convalescent phases (2 and 4 weeks) after natural infection with H1N1 Pdm in 2009. IgE antibodies developed following the vaccination of young children with seasonal split vaccines, whereas no significant IgE response was observed following natural infection with H1N1 Pdm 2009. The prevalence of IgE antibodies was not influenced by outbreaks of H1N1 Pdm. Repeated immunization with the HA split vaccine induced IgE sensitization against the influenza vaccine irrespective of the H1N1, H3N2, or B influenza subtypes. The reasons why anaphylaxis only occurred in recipients of the influenza vaccine containing 2-phenoxyethanol are still being investigated, and the size distribution of antigen particles may have shifted to a slightly larger size. Since the fundamental reason was IgE sensitization, current split formulation for the seasonal influenza vaccine needs to be reconsidered to prevent the induction of IgE sensitization.

Humoral immune response to influenza A(H1N1)pdm2009 in patients with natural infection and in vaccine recipients in the 2009 pandemic.

The 2009 pandemic H1N1 mainly affected adolescents and children, and most of the elderly in Japan escaped clinical illness. To clarify the role of humoral immunity in the infection, the time kinetics of hemagglutination inhibition (HI), neutralization (NT), and IgG subclass antibody response directed against influenza A(H1N1)pdm2009 were analyzed in three consecutive specimens obtained from 51 young adults and children (group 1) who contracted pandemic influenza and from 74 pediatric clinic employees (group 2) inoculated with pandemic monovalent vaccine. In group 1 patients, 6 and 30 patients had lower HI and NT antibody in the acute phase respectively. Thereafter, HI and NT antibody titers increased fourfold or more in 50 patients with peak response in the third specimens obtained four weeks after the onset. IgG1 in 45 patients, IgG3 in 18 patients, and IgG4 in 29 patients showed elevated responses. Forty (54%) and 70 (95%) subjects in group 2 had positive HI and NT antibodies in the prevaccination samples, with increased antibody responses in the follow-up peaking in the second specimens. Forty of those vaccinated had increased IgG1 responses peaking in the third specimens, whereas elevated IgG3 was observed in 22 recipients with the highest level in the second samples. IgG4 did not show any increase in subjects in group 2. A few participants showed an IgG2 response in both groups. An immunologically naive population contracted influenza with apparent clinical symptoms. However, already primed subjects through subclinical infection elicited the unique pattern of IgG subclass responses by vaccination, which differed from those of naive populations.

Serum levels of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinases-1 in human herpesvirus-6-infected infants with or without febrile seizures.

Human herpesvirus-6 (HHV-6) is a cause of exanthema subitum and, sometimes, of febrile seizures. However, the pathogenesis of febrile seizures associated with HHV-6 infection remains unclear. We investigated serum matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinases-1 (TIMP-1) levels in infants with HHV-6 infection. Serum levels of both MMP-9 and TIMP-1 were significantly higher in infants with HHV-6 infection than in controls. Serum TIMP-1 levels were significantly higher in infants with febrile seizures than in infants without febrile seizures. Serum MMP-9/TIMP-1 ratios were significantly lower in infants with febrile seizures than in infants without febrile seizures. In infants with HHV-6 infection, positive correlations were found between serum MMP-9 concentrations and the white blood cells (WBC) count, and between serum TIMP-1 concentrations and the WBC count. Positive correlations were also found between the amounts of HHV-6 DNA and the ratios of MMP-9/TIMP-1 in infants with HHV-6 infection. In conclusion, we suggest that high serum levels of MMP-9 and TIMP-1 in infants with HHV-6 infection may induce dysfunction of the blood-brain barrier, eventually causing febrile seizures.

Effectiveness and safety of inactivated influenza vaccination in pediatric liver transplant recipients over three influenza seasons.

Annual influenza vaccination is recommended for pediatric liver transplant recipients, who are at high risk of influenza-related complications. However, effectiveness and safety of vaccination may differ among influenza seasons in this population and have not been fully evaluated. Subjects comprised 38 pediatric liver transplant recipients with or without influenza vaccination through the 2006-2007, 2007-2008 and 2008-2009 influenza seasons. Recipients received inactivated trivalent (AH1/AH3/B) influenza vaccine, and comparisons were made to non-vaccinated recipients with regard to effectiveness and safety. No significant differences were seen between recipient groups for acute allograft rejection, acute febrile illness, or influenza virus infection. No serious systemic adverse events were observed in vaccinated recipients. Seroprotection rate (defined as the proportion of recipients with HI antibody titer ≥ 1:40), seroconversion rate (proportion of recipients with a ≥ 4-fold increase in HI titers), and geometric mean titers were mostly elevated after vaccination for the three influenza antigens in each season. These three indicators of immunogenicity showed similar results in both vaccinated recipients and vaccinated healthy children in the 2007-2008 season. These findings suggest that pediatric liver transplant patients may respond safely to inactivated seasonal influenza vaccines in a similar manner to healthy children, and effectiveness varies among influenza seasons.

The course of fever following influenza virus infection in children treated with oseltamivir.

Although the effectiveness of oseltamivir against influenza virus infection is well known, there has been no report analyzing the detailed time course of fever following the drug treatment in children. Oseltamivir was prescribed for 4 days to every child with a positive result for rapid immunological test for influenza virus during 2002--2003, 2003--2004, and 2004--2005 epidemics. Only those who were 1-12 years of age and prescribed oseltamivir within 24 hr after the onset of fever were included in the analysis. The numbers of children with type A/H3N2 disease for the three seasons were 64, 77, and 33, and those with type B disease were 102, 4, and 86, for the respective seasons. The period until normalization of temperature was obtained from six-hourly recordings of body temperature. By multiple regression analysis, temperature periods were longer in type B than in type A/H3N2 disease, negatively associated with age, and positively with maximal body temperature (all: P < 0.001). The effectiveness of oseltamivir on body temperature in type B disease was less apparent in the 2004--2005 than in the 2002--2003 season, irrespective of age. No such between-season difference was observed for Type A/H3N2 disease. Frequencies of ineffective cases with biphasic fever (19.6% and 43.0% during 2002--2003 and 2004--2005 seasons) were significantly higher in type B than in type A/H3N disease (12.0% and 11.8%, respectively). The effectiveness of oseltamivir depends on a child's age, maximal body temperature and the virus type. This study confirmed recent reports indicating decreased effectiveness of oseltamivir against type B disease.

Quantitative detection and rapid identification of human adenoviruses.

We have established a method of quantitative detection and rapid identification of human adenoviruses (hAdVs). Using LightCycler PCR with a primer set, we were able to amplify 554 bp of the hexon gene from each of 51 prototype strains of hAdVs. The sensitivity of LightCycler PCR was 10 copies of hAdV DNA/reaction. When LightCycler PCR was performed using a set of primers, hAdV was positive for 74.4% (99 of 133) of conjunctivitis patients and for 27.3% (81 of 297) of respiratory infection patients. We also attempted to measure hAdV in the potentially contaminated eye drops used by patients, detecting 5.4 x 10(2) to 1.6 x 10(6) copies/ml of hAdV. We determined the 350-bp nucleotide sequence of the amplified hexon gene and compared it with the sequences of the 51 prototype strains. Phylogenetic analysis based on 350 bp of the hexon gene identified 99 positive conjunctival swabs as 24 cases of AdV type 3 (AdV-3), 14 cases of AdV-4, 1 case of AdV-8, 19 cases of AdV-19a, and 41 cases of AdV-37. The 81 sequences from pharyngeal or nasal mucus swabs were identified as 29 cases of AdV-2, 18 cases of AdV-1, 18 cases of AdV-5, 12 cases of AdV-4, 2 cases of AdV-37, 1 case of AdV-3, and 1 case of AdV-6. LightCycler PCR followed by phylogenetic analysis provides an effective tool for the rapid identification of hAdVs and for studying molecular epidemiology.

A comparative study of the incidence of aseptic meningitis in symptomatic natural mumps patients and monovalent mumps vaccine recipients in Japan.

To compare the incidence of aseptic meningitis associated with symptomatic natural mumps infection and in mumps vaccine recipients, we conducted a prospective comparative study. Consecutive samples of 1051 children with mumps were enrolled by 10 pediatricians and 21,465 vaccine recipients by 143 pediatric primary care practitioners, from January 1, 2000 to January 1, 2003. Parents used a daily diary to record symptoms during the period of illness (15 days) or 30-day period following immunization. Mumps infection was confirmed by virus isolation and/or detection of mumps virus genome in salivary and CSF samples. The incidence of aseptic meningitis was 13/1051 (1.24%) in patients with symptomatic natural mumps infection and was estimated to be 0.7-1.1% of overall infection in considering asymptomatic infection, and 10/21,465 (0.05%) in vaccine recipients. Although aseptic meningitis is a clear side effect of the mumps vaccine, the incidence is considerably lower than among those with symptomatic natural infection. Our results provide an informative data for consideration to resume mumps vaccine as a part of routine immunization schedule for Japanese children.

Natural course of fever during influenza virus infection in children.

During the 2001-2002 epidemic of influenza virus A/H1N1, A/H3N2, and B, the authors obtained detailed profiles of fever from 118 infected children. The only treatment given was acetaminophen for temperatures greater than 39.0 degrees C. Fever was most prominent in A/H3N2 and young children. Secondary fever was observed frequently at 72 to 132 hours in all types. The duration of fever was associated negatively with the age of the child and positively with the maximal temperature. The information will be no longer available in current era of oseltamivir therapy.

Efficacy of inactivated trivalent influenza vaccine in alleviating the febrile illness of culture-confirmed influenza in children in the 2000-2001 influenza season.

During the 2000/2001 influenza season in Japan, children ranging in age from 6 months to 13 years with fever exceeding 37.5 degrees C were recruited. Vaccine efficacy was evaluated by comparing the rates of pre-seasonal vaccination between groups stratified by fever severity. Seven hundred and sixty one patients (33.1%), culture positive for influenza were enrolled for analysis. The numbers of patients for A/H1N1 and A/H3N2 were insufficient for statistical analysis. For influenza B the odds ratio for vaccinated children to have a maximum fever exceeding 39.5 degrees C was 0.52 (95% CI, 0.30-0.92) Our findings suggest modest impact of influenza vaccination on limiting severity of disease symptoms.

Molecular epidemiology of mumps virus in Japan and proposal of two new genotypes.

We isolated 872 strains of mumps virus from naso-pharyngeal secretions in seven different districts of Japan from January 2000 to July 2001. Among them, 57 strains were geno-typed by nucleotide sequencing in part of the hemagglutinin-neuraminidase (HN) and small hydrophobic (SH) protein regions. Four different genotypes (B, G, K, and L) of mumps virus were co-circulating in Japan and the distribution of genotypes varied in geographically different districts. Two new clusters designated as genotypes K and L had more than 7% nucleotide variation in the SH gene. Among the 57 strains, 11 were classified as B, 35 as G, three as K, and eight as L, which was mainly isolated in Tokyo. We also examined 104 stains isolated in a clinic in Mie prefecture from 1993 to 2003. Genotype B was the indigenous strain and genotype K was introduced in 1994. Genotypes B and K co-circulated in the 1990s and were replaced by genotype G in 2000. There was no significant change in neutralizing test antibody titers against genotypes B, G, K, and L using seven post-vaccination sera with Hoshino strain (genotype B) and these four genotypes had a different antigenicity from genotype A. We should continue to watch on mumps virus molecular epidemiology.