Changes in vaccination administration in Japan.

This paper reviews the administration related to vaccination in Japan after the enactment of the Immunization Act in 1948, under which vaccination was implemented mandatory for the public. To enhance the effectiveness of vaccination activities, the government implemented group vaccination, which is convenient for vaccinating recipients all at once. In 1976, Japan established the relief system for health damage after vaccination. While some projects, such as the mass administration of live oral polio vaccine in 1961, achieved excellent results, incidents leading to health damage occurred, such as the diphtheria toxoid immunization incident (1948) and frequent occurrence of aseptic meningitis owing to the measles, mumps, and rubella vaccine (1989). In December 1992, the Tokyo High Court sentenced that the onset of health damage after vaccination could be attributed to the negligence of the national government. In the revision of the Immunization Act in 1994, the "mandatory vaccination" enforced until then was changed to "recommended vaccination." The Act was also changed to recommend "individual vaccination" in principle, which is performed after primary care physicians investigate the physical condition of individual recipients and carefully conduct preliminary examination. For approximately 20 years from the 1990s, a vaccine gap existed between Japan and other countries. From around 2010, efforts have been made to bridge this gap and establish the global standard in vaccination.

Acute and Postacute Clinical Characteristics of Coronavirus Disease 2019 in Children in Japan.

BACKGROUND: The clinical features of coronavirus disease 2019 (COVID-19) in children have been changing because of the emergence and rapid spread of variants of concern (VOC). The increase in cases infected with VOC has brought concern with persistent symptoms after COVID-19 in children. This survey aimed to analyze the clinical manifestations and persistent symptoms of pediatric COVID-19 cases in Japan. METHODS: We analyzed the clinical manifestations of pediatric COVID-19 cases reported between February 2020 and April 2022 in Japan, using a dedicated database updated voluntarily by the members of the Japan Pediatric Society. Using the same database, we also analyzed persistent symptoms after COVID-19 in children who were diagnosed between February 2020 and November 2021. RESULTS: A total of 5411 and 1697 pediatric COVID-19 cases were included for analyzing clinical manifestations and persistent symptoms, respectively. During the Omicron variant predominant period, the percentage of patients with seizures increased to 13.4% and 7.4% in patient groups 1-4 and 5-11 years of age, respectively, compared with the pre-Delta (1.3%, 0.4%) or Delta period (3.1%, 0.0%). Persistent and present symptoms after 28 days of COVID-19 onset were reported in 55 (3.2%). CONCLUSIONS: Our survey showed that the rate of symptomatic pediatric COVID-19 cases increased gradually, especially during the Omicron variant predominant period, and a certain percentage of pediatric cases had persistent symptoms. Certain percentages of pediatric COVID-19 patients had severe complications or prolonged symptoms. Further studies are needed to follow such patients.

Dimerized fusion inhibitor peptides targeting the HR1-HR2 interaction of SARS-CoV-2.

Membrane fusion is a critical and indispensable step in the replication cycles of viruses such as SARS-CoV-2 and human immunodeficiency virus type-1 (HIV-1). In this step, a trimer of the heptad repeat 1 (HR1) region interacts with the three HR2 regions and forms a 6-helix bundle (6-HB) structure to proceed with membrane fusion of the virus envelope and host cells. Recently, several researchers have developed potent peptidic SARS-CoV-2 fusion inhibitors based on the HR2 sequence and including some modifications. We have developed highly potent HIV-1 fusion inhibitors by dimerization of its HR2 peptides. Here, we report the development of dimerized HR2 peptides of SARS-CoV-2, which showed significantly higher antiviral activity than the corresponding monomers, suggesting that the dimerization strategy can facilitate the design of potent inhibitors of SARS-CoV-2.

Adverse events after administration of the first and second doses of messenger RNA-based COVID-19 vaccines in Japanese subjects aged 12-18 years.

OBJECTIVE: Using a prospective observational design, we assessed adverse events (AEs) after COVID-19 vaccination in Japanese patients. METHODS: Two doses of the mRNA-1273 (SPIKEVAX®) or BNT162b2 (COMIRNATY®) vaccine were administered to participants aged 12 to 18 years, and AEs after each dose were recorded for 14 days. Data on the duration and nature (local vs. systemic) of AEs were collected using a questionnaire. Sex-based differences in AE frequency were also analyzed. RESULTS: After the first and second doses, 152 and 135 vaccinees were enrolled, respectively. After the first dose, fever (>37.1°C) occurred in 38.9% of males and 50.0% of females, whereas local pain occurred in 89.8% and 97.7% of males and females, respectively (only SPIKEVAX® was used as the first dose). After the second dose, fever (>37.1°C) occurred in 77.8% and 82.6% of males vaccinated with COMIRNATY® and SPIKEVAX®, respectively, and 82.6% of females (all received SPIKEVAX®). The local pain rates in these groups were 80.6%, 76.3%, and 100%, respectively. After the second dose, local pain, fever (>38.1°C) and headache were significantly more common in female participants, and the median symptom duration was 3 days. CONCLUSIONS: AEs were more frequent after the second dose and in females.

Disinfection of otorhinolaryngological endoscopes with electrolyzed acid water: A cross-sectional and multicenter study.

Glutaraldehyde, a germicide for reprocessing endoscopes that is important for hygiene in the clinic, might be hazardous to humans. Electrolyzed acid water (EAW) has a broad anti-microbial spectrum and safety profile and might be a glutaraldehyde alternative. We sought to assess EAW disinfection of flexible endoscopes in clinical otorhinolaryngological settings and its in vitro inactivation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and bacteria commonly isolated in otorhinolaryngology. Ninety endoscopes were tested for bacterial contamination before and after endoscope disinfection with EAW. The species and strains of bacteria were studied. The in vitro inactivation of bacteria and SARS-CoV-2 by EAW was investigated to determine the efficacy of endoscope disinfection. More than 20 colony-forming units of bacteria at one or more sampling sites were detected in 75/90 microbiological cultures of samples from clinically used endoscopes (83.3%). The most common genus detected was Staphylococcus followed by Cutibacterium and Corynebacterium at all sites including the ears, noses, and throats. In the in vitro study, more than 107 CFU/mL of all bacterial species examined were reduced to below the detection limit (<10 CFU/mL) within 30 s after contact with EAW. When SARS-CoV-2 was treated with a 99-fold volume of EAW, the initial viral titer (> 105 PFU) was decreased to less than 5 PFU. Effective inactivation of SARS-CoV-2 was also observed with a 19:1 ratio of EAW to the virus. EAW effectively reprocessed flexible endoscopes contributing to infection control in medical institutions in the era of the coronavirus disease 2019 pandemic.

Proposal for the revision of guidelines for clinical trials of vaccines to prevent infectious diseases in Japan.

The development of vaccines against infectious diseases requires a different approach from that of therapeutics, because vaccines are inoculated into healthy individuals and have a preventive effect by activating the immunity of the inoculated human. In Japan, "The Guideline for Clinical Trials of Vaccines for the Prevention of Infectious Diseases" was published in 2010 before changes occurred in the vaccine development environment in Japan, such as the introductions of foreign vaccines and simultaneous global development. This study aimed to identify current challenges in vaccine development through a questionnaire-based survey of pharmaceutical companies in Japan and by comparing the domestic and international guidelines and surveying review reports of 35 vaccines approved in Japan between April 2010 and December 2020. Identified challenges included the requirement for protective efficacy trials, efficacy evaluation of combination vaccines, development of multiregional and foreign clinical trials, and immunization of older adults and immunocompromised patients. We propose that new vaccines against infectious diseases should be evaluated for the protective efficacy, preferably through multiregional clinical trials. Additionally, differences in the incidence of infectious diseases or in epidemic virus strains between regions may affect the trials, when multiregional clinical trials are conducted, but immunogenicity-based studies can be conducted if a correlation between protective efficacy and immunogenicity has been established. We suggest that licensed combination vaccines can be used as comparators when an antigen is added to a licensed combination vaccine. We also proposed that the efficacy of a vaccine in non-major subjects, such as older adults or immunocompromised patients could be evaluated by comparing immunogenicity in major subjects with the confirmed protective effects of the vaccine. It is expected that these revisions will lead to the rapid advancement of vaccine development, which should contribute to the improvement of public health.

The Effects of Behavioral Restrictions on the Spread of COVID-19

Several measures, including behavioral restrictions for individuals, have been taken throughout the world to control the spread of COVID-19. The aim of these measures is to prevent infected persons from coming into contact with susceptible persons. Since the behavioral restrictions for all citizens, such as city-wide lockdowns, were directly linked to the stagnation of economic activities, the assessment of such measures is crucial. In order to evaluate the effects of behavioral restrictions, we employed the broken-link model to compare the situation of COVID-19 in Shanghai, where a lockdown was implemented from March to June 2022, with the situation in Taiwan, where the spread of COVID-19 has been well controlled so far. The results show that the small link-connection probability was achieved by the substantial isolation of infected persons, including the lockdown measures. Although the strict measures for behavioral restrictions were effective to reduce the total number infected people, the daily reported cases per one million people followed the curve evaluated by the broken-link model. This result considers that infections are unavoidable for the population.

Acceptance of Booster COVID-19 Vaccine and Its Association with Components of Vaccination Readiness in the General Population: A Cross-Sectional Survey for Starting Booster Dose in Japan.

The Japanese government approved COVID-19 vaccine booster doses in November 2021. However, intentions and readiness for booster vaccines among the general population were unknown. This survey measured the intentions for COVID-19 booster vaccination. Among 6172 participants (53.2% female), 4832 (78.3%) accepted booster doses; 415 (6.7%) hesitated. Vaccination intention was associated with higher age, marital status, having children, underlying diseases, and social norms. To evaluate the readiness for vaccination, the seven component (7C) vaccination readiness scale was employed, comprising "Confidence", "Complacency", "Constraints", "Calculation", "Collective responsibility", "Compliance", and "Conspiracy". Participants with acceptance showed significantly higher 7C scores (p < 0.001) than those who hesitated or were unsure. Multivariable logistic regression analysis revealed that the "social norms" predictor was the strongest predictor of acceptance (adjusted odds ratio (AOR) 4.02, 95% confidence interval (CI): 3.64-4.45). "Constraints" (AOR: 2.27, 95% CI: 2.11-2.45) and "complacency" (AOR: 2.18, 95% CI: 2.03-2.34) were also strongly associated with acceptance, but "compliance" (AOR: 1.24, 95% CI: 1.18-1.31) and "conspiracy" (AOR: 1.42, 95% CI: 1.33-1.52) were weakly associated. The "7C vaccination readiness scale" is useful for measuring vaccine acceptance in the Japanese population. However, "social norms" might be more suitable than "compliance" and "conspiracy" for measuring vaccine acceptance in Japan.

A New Compartment Model of COVID-19 Transmission: The Broken-Link Model.

We propose a new compartment model of COVID-19 spread, the broken-link model, which includes the effect from unconnected infectious links of the transmission. The traditional SIR-type epidemic models are widely used to analyze the spread status, and the models show the exponential growth of the number of infected people. However, even in the early stage of the spread, it is proven by the actual data that the exponential growth did not occur all over the world. We presume this is caused by the suppression of secondary and higher-order transmissions of COVID-19. We find that the proposed broken-link model quantitatively describes the mechanism of this suppression, which leads to the shape of epicurves of confirmed cases are governed by the probability of unconnected infectious links, and the magnitudes of the cases are proportional to expR0 in each infectious surge generated by a virus of the basic reproduction number R0, and is consistent with the actual data.

Proposal for the revision of the guidelines for Non-clinical studies of vaccines for the prevention of infectious diseases in Japan.

The efficacy and safety of vaccines for the prevention of infectious diseases are mostly evaluated based on the induction of an immune response against antigens, and do not necessarily depend on the dose administered. Therefore, there are some specific aspects that need to be considered in the development of vaccines and have been described in "The Guidelines for the non-clinical studies of vaccines for the prevention of infectious disease" in Japan. Recent changes in the vaccine development field, such as the introduction of vaccines developed overseas in Japan and vaccine development on a global scale have increased the need for revision of these guidelines. In this study, we identified the current challenges in the development of vaccines through comparison of Japanese and international guidelines. We conducted a questionnaire-based survey of pharmaceutical industries in Japan, and found issues related to non-clinical studies, such as the necessity of safety pharmacology studies and repeated-dose toxicity studies for each route of administration. We examined international guidelines on these issues as well as review reports by regulatory authorities, and determined that the results of repeated-dose toxicity studies can be used to decide whether safety pharmacology studies are required, and that studies to evaluate toxicity due to systemic effects may not be necessary for both intramuscular and subcutaneous administration. We propose revision of the guidelines for the non-clinical studies of vaccines in Japan taking international harmonizaion into account. We expected that the revised guidelines will promote smooth and rational vaccine development.

Association of Vaccine Confidence and Hesitancy in Three Phases of COVID-19 Vaccine Approval and Introduction in Japan.

Understanding vaccine hesitancy, considering the target region and phase, is an urgent issue to quell the coronavirus disease (COVID-19) pandemic. This study aimed to monitor COVID-19 vaccine hesitancy in the Japanese population during the three phases of vaccine approval and introduction, and evaluate the association of vaccine hesitancy with vaccine confidence and literacy. We conducted web-based cross-sectional surveys during the three phases of COVID-19 vaccine introduction: January 2021, before approval; June, start of vaccination of the elderly; and September, when about 70% of the target population was vaccinated with at least one dose. There were 7210 participants, aged 20-80 years. We evaluated the association of vaccine hesitancy with vaccine confidence and literacy in the three phases using multivariate logistic regression analysis. The proportion of hesitancy in January, June, and September was 17.5%, 65.3%, and 19.4%, respectively. In any phase, lower vaccine confidence and literacy showed a higher adjusted odds ratio (AOR) of vaccine hesitancy in most items (AOR > 1, p < 0.001). Vaccine hesitancy in June had a different trend in perception of COVID-19 compared to that in the January and September surveys. The findings suggested that hesitancy increases transiently during vaccination introduction phases, and changes as the vaccination program progressed or waves of epidemic. Careful risk communication to increase vaccine confidence and literacy is essential to reduce vaccine hesitancy, especially in the introduction phase.

Three-dimensional reconstruction by electron tomography for the application to ultrastructural analysis of SARS-CoV-2 particles.

SARS-CoV-2 is the cause of COVID-19. The three-dimensional morphology of viral particles existing and multiplying in infected cells has not been established by electron tomography, which is different from cryo-electron tomography using frozen samples. In this study, we establish the morphological structure of SARS-CoV-2 particles by three-dimensional reconstruction of images obtained by electron tomography and transmission electron microscopy of biological samples embedded in epoxy resin. The characteristic roots of spike structures were found to be arranged at the surface of a virion covered with an envelope. A high-electron-density structure that appears to be a nucleocapsid was observed inside the envelope of the virion on three-dimensional images reconstructed by electron tomography. The SARS-CoV-2 particles that budded in the vacuoles in the cytoplasm were morphologically identical to those found outside the cells, suggesting that mature and infectious SARS-CoV-2 particles were already produced in the vacuoles. Here, we show the three-dimensional morphological structure of SARS-CoV-2 particles reconstructed by electron tomography. To control infection, inhibition of viral release from vacuoles would be a new target in the development of prophylactic agents against SARS-CoV-2.

Differences in COVID-19 Vaccine Acceptance, Hesitancy, and Confidence between Healthcare Workers and the General Population in Japan.

Little is known about the differences in coronavirus disease (COVID-19) vaccine acceptance and hesitancy between the general population and healthcare workers in Japan. To compare these differences, a nationwide web-based cross-sectional survey was conducted on 19 January 2021, shortly before the initiation of COVID-19 vaccinations in Japan. A total of 6180 men and women aged 20-69 years and 1030 healthcare workers aged 20-69 years were enrolled. Data on COVID-19 vaccine acceptance, basic characteristics, including socioeconomic factors, and confidence in immunization in general were collected. COVID-19 vaccine acceptance was also evaluated under hypothetical vaccine effectiveness and adverse event frequencies. Factors associated with vaccine hesitancy were examined using multinomial logistic regression analysis. The COVID-19 vaccine acceptance rate was 48.6% among the general population and was lower among nurses (45.5%) and medical clerks (40.7%). Women and young adults had significantly higher COVID-19 vaccine hesitancy odds ratios, and current smokers had significantly lower odds ratios. The frequency of adverse events was a COVID-19 vaccine hesitancy factor. Even if these factors were adjusted, COVID-19 vaccine hesitancy among nurses was 1.4 times higher than that among the general population. Thus, interventions to improve health literacy and vaccine hesitancy among the general population and healthcare workers, especially nurses, are needed.

Survey on the SARS-CoV-2 additional vaccination

Strong alkaline electrolyzed water efficiently inactivates SARS-CoV-2, other viruses, and Gram-negative bacteria.

Air spaces and material surfaces in a pathogen-contaminated environment can often be a source of infection to humans, and disinfection has become a common intervention focused on reducing the contamination levels. In this study, we examined the efficacy of SAIW, a unique electrolyzed water with chlorine-free, high pH, high concentration of dissolved hydrogen, and low oxygen reduction potential, for the inactivation of several viruses and bacteria. Infectivity assays revealed that initial viral titers of enveloped and non-enveloped viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A virus, herpes simplex virus type 1, human coronavirus, feline calicivirus, and canine parvovirus, were reduced by 2.9- to 5.5-log10 within 30 s of SAIW exposure. Similarly, the culturability of three Gram-negative bacteria (Escherichia coli, Salmonella, and Legionella) dropped down by 1.9- to 4.9-log10 within 30 s of SAIW treatment. Mechanistically, treatment with SAIW was found to significantly decrease the binding and subsequent entry efficiencies of SARS-CoV-2 on Vero cells. Finally, we showed that this chlorine-free electrolytic ion water had no acute inhalation toxicity in mice, demonstrating that SAIW holds promise for a safer antiviral and antibacterial disinfectant.

The clinical characteristics of pediatric coronavirus disease 2019 in 2020 in Japan.

BACKGROUND: The COVID-19 pandemic has affected the lives of people of all ages. Most reports on pediatric cases suggest that children experience fewer and milder symptoms than do adults. This is the first nationwide study in Japan focusing on pediatric cases reported by pediatricians, including cases with no or mild symptoms. METHODS: We analyzed the epidemiological and clinical characteristics and transmission patterns of 840 pediatric (<16 years old) COVID-19 cases reported between February and December 2020 in Japan, using a dedicated database which was maintained voluntarily by members of the Japan Pediatric Society. RESULTS: Almost half of the patients (47.7%) were asymptomatic, while most of the others presented mild symptoms. At the time of admission or first outpatient clinic visit, 84.0% of the cases were afebrile (<37.5°C). In total, 609 cases (72.5%) were exposed to COVID-19-positive household members. We analyzed the influence of nationwide school closures that were introduced in March 2020 on COVID-19 transmission routes among children in Japan. Transmission within households occurred most frequently, with no significant difference between the periods before and after declaring nationwide school closures (70.9% and 74.5%, respectively). CONCLUSIONS: COVID-19 symptoms in children are less severe than those in adults. School closure appeared to have a limited effect on transmission. Controlling household transmission from adult family members is the most important measure for prevention of COVID-19 among children.

Evaluation of SARS-CoV-2 RNA quantification by RT-LAMP compared to RT-qPCR.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) is a global pandemic caused by a novel virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The viral load of SARS-CoV-2 is associated with mortality in COVID-19 patients. Measurement of viral load requires the use of reverse transcription quantitative PCR (RT-qPCR), which in turn requires advanced equipment and techniques. In this study, we aimed to evaluate the viral load measurement using reverse transcription loop-mediated isothermal amplification (RT-LAMP), which is a simpler procedure compared to RT-qPCR. MATERIALS AND METHODS: RNA was extracted by using the QIAamp Viral RNA Mini Kit. The RT-LAMP assay was performed by using the Loopamp® 2019-SARS-CoV-2 detection reagent kit and 10-fold serial dilutions of known viral load RT-LAMP were used to measure Tt, which is the time until the turbidity exceeds the threshold. Based on the relationship between viral load and Tt, the linearity and detection sensitivity of the calibration curve were evaluated. In addition, 117 clinical specimens were measured, and RT-qPCR and RT-LAMP assay results were compared. RESULTS: The dilution linearity of the calibration curve was maintained at five orders of magnitude 1.0× 106 to 1.0 × 101 copies/µL, and was confirmed to be detectable down to 1.0 × 100 copies/µL. The limit of quantification of RNA extracted from clinical specimens using RT-LAMP correlated well with that obtained using RT-qPCR (r2 = 0.930). CONCLUSION: The findings indicate that RT-LAMP is an effective method to determine the viral load of SARS-CoV-2.

Correlation of student performance on clerkship with quality of medical chart documentation in a simulation setting.

BACKGROUND: Medical chart documentation is an essential skill acquired in a clinical clerkship (CC). However, the utility of medical chart writing simulations as a component of the objective structured clinical examination (OSCE) has not been sufficiently evaluated. In this study, medical chart documentation in several clinical simulation settings was performed as part of the OSCE, and its correlation with CC performance was evaluated. METHODS: We created a clinical situation video and images involving the acquisition of informed consent, cardiopulmonary resuscitation, and diagnostic imaging in the emergency department, and assessed medical chart documentation performance by medical students as part of the OSCE. Evaluations were conducted utilizing original checklist (0-10 point). We also analyzed the correlation between medical chart documentation OSCE scores and CC performance of 120 medical students who performed their CC in 2019 as 5th year students and took the Post-CC OSCE in 2020 as 6th year students. RESULTS: Of the OSCE components, scores for the acquisition of informed consent and resuscitation showed significant correlations with CC performance (P<0.001 for each). In contrast, scores for diagnostic imaging showed a slightly positive, but non-significant, correlation with CC performance (P = 0.107). Overall scores for OSCE showed a significant correlation with CC performance (P<0.001). CONCLUSION: We conducted a correlation analysis of CC performance and the quality of medical chart documentation in a simulation setting. Our results suggest that medical chart documentation can be one possible alternative component in the OSCE.

Survey on the SARS-CoV-2 serum antibody retention and health condition both before and after the SARS-CoV-2 vaccine introduction