Factors Influencing Compliance With Social Distancing as a Nonpharmaceutical Intervention Before Vaccine Availability During the COVID-19 Pandemic: A Cross-Sectional Study in South Korea.

This study aimed to identify factors influencing compliance with social distancing, a key nonpharmaceutical intervention during the early stages of the coronavirus disease (COVID-19) pandemic. The study population comprised 182 758 Koreans who participated in the 2020 Community Health Survey. Personal characteristics were classified into sociodemographic, health behavioral, and psychosocial factors, and factors associated with social distancing compliance were identified. Health behaviors and psychosocial factors were highly related to compliance with social distancing. Approximately 13% of smokers were less likely to practice physical distancing and 50% of high-risk drinkers were less likely to limit going out or attending gatherings and events. Higher concern about COVID-19 and a more positive perception of the government's response policy were associated with a higher compliance with social distancing. Strategic public health policies considering the characteristics of the public are needed to enhance compliance with nonpharmaceutical interventions during disease outbreaks lacking effective treatments and vaccines.

Aetiology and Prognosis of Encephalitis in Korean Children: A Retrospective Single-Centre Study, 2005-2020.

PURPOSE: Encephalitis is a heterogeneous syndrome that occurs in childhood and is not rare. However, epidemiological studies of encephalitis based on the International Encephalitis Consortium (ICS) and expert recommendations are lacking. We investigated the aetiology and prognosis of encephalitis in Korean children. MATERIALS AND METHODS: This retrospective study included children aged <19 years hospitalised for encephalitis at Severance Children's Hospital between 2005 and 2020. The 2013 ICS criteria were used to diagnose encephalitis, and causality was classified according to the site from which the specimen was obtained. Neurological sequelae were categorised using the modified Rankin Scale (mRS) score. RESULTS: In total, 551 children were included, with 7% classified as possible, 77% as probable, and 15% as proven cases. A cause was identified in 42% of the cases (n=222), with viruses being the most common (42%), followed by bacteria (38%) and autoimmune encephalitis (12%). In cases of proven/probable encephalitis (n=65), bacteria accounted for 52%, followed by viruses (25%) and autoimmune encephalitis (22%). In cases with a single pathogen, the anti-N-methyl-D-aspartate receptor autoantibody (n=14) was the most common, followed by Group B streptococcus (n=13), herpes simplex virus (n=11), enterovirus (n=4), and others. Approximately 37% of patients had severe sequelae (mRS score ≥3) at discharge, which decreased to 31% 6 months after discharge. CONCLUSION: This large-scale study showed that autoimmune and infectious causes accounted for a significant proportion of encephalitis in Korean children. Further studies are needed to determine whether early targeted treatment following early diagnosis leads to a favourable prognosis in these populations.

In-hospital catatonia, delirium, and coma and mortality: Results from the delirium and catatonia prospective cohort investigation.

BACKGROUND: Catatonia, a form of acute brain dysfunction typically linked with severe affective and psychotic disorders, occurs in critical illness with delirium and coma. Delirium and coma are associated with mortality, though catatonia's relationship with mortality is unclear. We aim to describe whether catatonia, delirium, and coma are associated with mortality. METHODS: We enrolled a convenience cohort of critically ill adults (N = 378) at an academic medical center. We assessed catatonia, delirium, and coma using the Bush-Francis Catatonia Rating Scale, the Confusion Assessment Method for the Intensive Care Unit and the Richmond Agitation-Sedation Scale, respectively. We tested the associations between previous day brain dysfunction state occurrence with in-hospital and one-year mortality using multivariable time-dependent risk models. Additionally, we tested the association between brain dysfunction duration and one-year mortality. RESULTS: Catatonia was not associated with death on the day after diagnosis during hospitalization, and neither previous catatonia occurrence nor duration was associated with one-year mortality. Delirium was not associated with death on any day following diagnosis during hospitalization, and neither previous delirium occurrence nor duration was associated with one-year mortality. The occurrence of coma was associated with death on any day after diagnosis during hospitalization (HR 2.30,CI 1.19-4.44,p = 0.014), as well as through one year following hospital discharge (HR 1.68,CI 1.09-2.59,p = 0.02). CONCLUSIONS: Coma, but neither catatonia nor delirium, was associated with future day in-hospital and one-year mortality. More research is needed to understand catatonia's clinical impact. Delirium results differ from existing literature likely due to cohort demographics and size. Coma results highlight the prognostic significance of suppressed arousal while critically ill.

Sex differences in COVID-19 symptom severity and trajectories among ambulatory adults.

Background: The ongoing COVID-19 pandemic has led to hundreds of millions of infections worldwide. Although differences in COVID-19 hospitalization rates between males and females have been described, many infections in the general population have been mild, and the severity of symptoms during the course of COVID-19 in non-hospitalized males and females is not well understood. Methods: We conducted a case-ascertained study to examine household transmission of SARS-CoV-2 infections in Nashville, Tennessee, between April 2020 and April 2021. Among enrolled ambulatory adult participants with laboratory-confirmed SARS-CoV-2 infections, we assessed the presence and severity of symptoms (total, systemic, and respiratory) daily using a symptoms severity questionnaire, from illness onset and throughout the 2-week follow-up period. We compared the mean daily symptom severity scores (0-3: none, mild, moderate, and severe) and change in symptoms between males and females using a multivariable linear mixed effects regression model. Results: The analysis included 223 enrolled adults with SARS-CoV-2 infection (58% females, mostly white, non-Hispanic) from 146 households with 2917 total daily symptom reports. The overall mean severity of total symptoms reported over the illness period was 1.04 and 0.90 for females and males, respectively. Mean systemic and respiratory scores were higher for females than for males (p < 0.001). In multivariable analyses, females reported more severe total and systemic symptoms during the illness period compared with males. However, no significant differences in reported respiratory symptoms were observed. Conclusions: Our findings indicate that among ambulatory adults with SARS-CoV-2 infections, females reported slightly higher symptom severity during their illness compared with males.

Comparison of Humoral Response between Third and Fourth Doses of COVID-19 Vaccine in Hemodialysis Patients.

Dialysis patients are more likely to die or become hospitalized from coronavirus disease 2019 (COVID-19). Currently, only a few studies have evaluated the efficacy of a fourth booster vaccination in hemodialysis (HD) patients and there is not enough evidence to recommend for or against a fourth booster vaccination. This study compared the humoral response and disease severity of patients on HD who received either three or four doses of COVID-19 vaccine. A total of 88 patients were enrolled. Humoral response to vaccination was measured by quantifying immunoglobulin G levels against the receptor binding domain of SARS-CoV-2 (anti-RBD IgG) at five different times and plaque reduction neutralization tests (PRNT) at two different times after vaccination over a period of 18 months. Antibody levels were measured at approximately two-month intervals after the first and second dose, then four months after the third dose, and then one to six months after the fourth dose of vaccine. PRNT was performed two months after the second and four months after the third dose of vaccine. We classified patients into four groups according to the number of vaccine doses and presence of COVID-19 infection. Severe infection was defined as hospital admission for greater than or equal to two weeks or death. There was no difference in antibody levels between naïve and infected patients except after a fourth vaccination, which was effective for increasing antibodies in infection-naïve patients. Age, sex, body mass index (BMI), dialysis vintage, and presence of diabetes mellitus (DM) did not show a significant correlation with antibody levels. Four patients who experienced severe COVID-19 disease tended to have lower antibody levels prior to infection. A fourth dose of SARS-CoV-2 vaccine significantly elevated antibodies in infection-naïve HD patients and may be beneficial for HD patients who have not been previously infected with SARS-CoV-2 for protection against severe infection.

Comparison of health inequalities according to socioeconomic status: findings from the fourth Korean working condition survey (a cross-sectional study).

Introduction: this study aims to examine health inequalities among Korean workers by sex, age, education, monthly income, occupation, and employment type and identify groups of workers who may be neglected in the process of resolving health inequalities. Methods: we used data from the Fourth Korean Working Condition Survey conducted by the Korea Occupational Safety and Health Research Institute and compared the number of health symptoms among various groups using the t-test and one-way analysis of variance to determine their health status. We also calculated the Gini index of the number of health symptoms of each group and plotted the Lorenz curve to illustrate health inequalities. Results: we found that the number of health symptoms was higher in groups with lower socioeconomic status (e.g., female, blue-collar workers, older, low education, low monthly income, and self-employed workers). However, the Gini index and Lorenz curve with respect to socioeconomic status indicated that health inequalities were higher among white-collar and permanent workers vis-à-vis blue-collar and self-employed workers, respectively. Further, it was found that health inequalities were higher among males than females with respect to the same occupational groups and employment types. Conclusion: general health policies are often targeted at the socially and economically vulnerable group, but according to the results of this study, it can be considered that there may be subjects who are vulnerable to health problems even in groups that are not socioeconomically vulnerable.

Cryptococcal Meningitis and Clinical Outcomes in Persons With Human Immunodeficiency Virus: A Global View.

BACKGROUND: Cryptococcal meningitis (CM) is a major cause of morbidity and mortality in persons with human immunodeficiency virus (HIV; PWH). Little is known about CM outcomes and availability of diagnostic and treatment modalities globally. METHODS: In this retrospective cohort study, we investigated CM incidence and all-cause mortality in PWH in the International Epidemiology Databases to Evaluate AIDS cohort from 1996 to 2017. We estimated incidence using quasi-Poisson models adjusted for sex, age, calendar year, CD4 cell count (CD4), and antiretroviral therapy (ART) status. Mortality after CM diagnosis was examined using multivariable Cox models. A site survey from 2017 assessed availability of CM diagnostic and treatment modalities. RESULTS: Among 518 852 PWH, there were 3857 cases of CM with an estimated incidence of 1.54 per 1000 person-years. Mortality over a median of 2.6 years of post-CM diagnosis follow-up was 31.6%, with 29% lost to follow-up. In total, 2478 (64%) were diagnosed with CM after ART start with a median of 253 days from ART start to CM diagnosis. Older age (hazard [HR], 1.31 for 50 vs 35 years), lower CD4 (HR, 1.15 for 200 vs 350 cells/mm3), and earlier year of CM diagnosis (HR, 0.51 for 2015 vs 2000) were associated with higher mortality. Of 89 sites, 34% reported access to amphotericin B; 12% had access to flucytosine. CONCLUSIONS: Mortality after CM diagnosis was high. A substantial portion of CM cases occurred after ART start, though incidence and mortality may be higher than reported due to ascertainment bias. Many sites lacked access to recommended CM treatment.

Improved Immunogenicity of the Inactivated F Genotype Mumps Vaccine against Diverse Circulating Mumps Viruses in Mice.

Mumps is an acute infectious disease caused by the mumps virus (MuV). Despite high global vaccination coverage, mumps outbreaks continue to occur, even in vaccinated populations. Therefore, we aimed to identify candidate vaccines that can induce an immunogenic response against diverse MuV genotypes with greater efficacy than the currently available options. Vaccine candidates were sourced using formalin-inactivated viral strains. The inactivated vaccines were administered to BALB/c mice (through a primer and booster dose administered after a three-week interval). We tested the neutralizing antibodies of the candidate vaccines against various MuV genotypes to determine their overall efficacy. The formalin-inactivated F genotype vaccine was found to have higher cross-neutralizing titers against genotypes F, H, and G as well as significant Th1 cytokines responses, IFN-γ, TNF-α, and IL-2 than the Jeryl Lynn (JL) vaccine. Our findings suggest that the inactivated F genotype mumps vaccine has higher immunogenicity than the JL vaccine against diverse circulating MuVs.

Household Transmission of Influenza A Viruses in 2021-2022.

Importance: Influenza virus infections declined globally during the COVID-19 pandemic. Loss of natural immunity from lower rates of influenza infection and documented antigenic changes in circulating viruses may have resulted in increased susceptibility to influenza virus infection during the 2021-2022 influenza season. Objective: To compare the risk of influenza virus infection among household contacts of patients with influenza during the 2021-2022 influenza season with risk of influenza virus infection among household contacts during influenza seasons before the COVID-19 pandemic in the US. Design, Setting, and Participants: This prospective study of influenza transmission enrolled households in 2 states before the COVID-19 pandemic (2017-2020) and in 4 US states during the 2021-2022 influenza season. Primary cases were individuals with the earliest laboratory-confirmed influenza A(H3N2) virus infection in a household. Household contacts were people living with the primary cases who self-collected nasal swabs daily for influenza molecular testing and completed symptom diaries daily for 5 to 10 days after enrollment. Exposures: Household contacts living with a primary case. Main Outcomes and Measures: Relative risk of laboratory-confirmed influenza A(H3N2) virus infection in household contacts during the 2021-2022 season compared with prepandemic seasons. Risk estimates were adjusted for age, vaccination status, frequency of interaction with the primary case, and household density. Subgroup analyses by age, vaccination status, and frequency of interaction with the primary case were also conducted. Results: During the prepandemic seasons, 152 primary cases (median age, 13 years; 3.9% Black; 52.0% female) and 353 household contacts (median age, 33 years; 2.8% Black; 54.1% female) were included and during the 2021-2022 influenza season, 84 primary cases (median age, 10 years; 13.1% Black; 52.4% female) and 186 household contacts (median age, 28.5 years; 14.0% Black; 63.4% female) were included in the analysis. During the prepandemic influenza seasons, 20.1% (71/353) of household contacts were infected with influenza A(H3N2) viruses compared with 50.0% (93/186) of household contacts in 2021-2022. The adjusted relative risk of A(H3N2) virus infection in 2021-2022 was 2.31 (95% CI, 1.86-2.86) compared with prepandemic seasons. Conclusions and Relevance: Among cohorts in 5 US states, there was a significantly increased risk of household transmission of influenza A(H3N2) in 2021-2022 compared with prepandemic seasons. Additional research is needed to understand reasons for this association.

Clinical hypnosis can reduce lower urinary tract symptoms in individuals with chronic pain.

STUDY PURPOSE: Lower urinary tract symptoms (LUTS) can occur in chronic pain populations at high rates and drastically affect quality of life. Hypnosis is a nonpharmacological treatment used in chronic pain known to have beneficial implications to health outside of pain reduction. This study evaluated the potential for hypnosis to reduce LUTS in a sample of individuals with chronic pain, if baseline LUTS severity affected outcomes, and specific LUTS that may respond to hypnosis. METHODS: Sixty-four adults with chronic pain and LUTS at a level of detectable symptom change (American Urological Association Symptom Index, AUASI 3) participated in an 8-week group hypnosis protocol. Participants completed validated assessments of LUTS, pain, and overall functioning before, after, 3- and 6-months posttreatment. Linear mixed effects models assessed improvement in LUTS over time while accounting for known factors associated with outcome (e.g., age, gender). The interaction of baseline symptom severity and treatment assessed the potential effect of baseline symptoms on change scores. RESULTS: Participants experienced significant and meaningful improvements in LUTS following group hypnosis (p = 0.006). There was a significant interaction between baseline symptom severity and treatment (p < 0.001), such that those with severe symptoms experienced the most pronounced gains over time (e.g., an 8.8 point reduction). Gains increased over time for those with moderate and severe symptoms. Changes in LUT symptoms occurred independently of pain relief. CONCLUSIONS: This pilot study suggests hypnosis has the potential to drastically improve LUTS in individuals with chronic pain, even when pain reduction does not occur. Results provide initial evidence for the treatment potential of hypnosis in urologic pain (and possibly non-pain/benign) populations, with randomized trials needed for definitive outcomes.

Greater gender diversity among autistic children by self-report and parent-report.

LAY ABSTRACT: Gender diversity broadly refers to the way in which an individual experiences (expressions and/or identities) their gender distinctly to that which would be expected based upon social norms for their gender assigned at birth. Recent research has shown a higher representation of gender diversity among autistic youth. Previous research in this area has relied on parent-report based on a single question from the Child Behavior Checklist Item-110, asking whether their child "Wishes to be the opposite sex." The Gender Diversity Screening Questionnaire Self-Report and Parent-Report were used to assess the experience of gender diversity in 244 children (140 autism spectrum disorder and 104 typically developing) between 10 and 13 years. The Item-110 was also collected. Results showed that autistic children endorsed much higher rates of Binary Gender Diversity (less identification with their designated sex and more with the other binary sex) and Nonbinary Gender Diversity (identification as neither male nor female) than typically developing children. Similarly, parents of autistic children reported significantly more gender-body incongruence experienced by their child than parents of typically developing children. Specifically, parents of autistic females-assigned-at-birth reported significantly more gender-body incongruence than autistic males-assigned-at-birth. Parent- and self-report measures were largely related. Moreover, statistical comparisons between and within the groups revealed associations between gender profiles and symptoms of anxiety, depression, and suicidality. Results extend previous reports showing increased rates of gender diversity in autistic children, now based on both self-report and parent-report, and highlight the need to better understand and support the unique and complex needs of autistic children who experience gender diversity.

Seroprevalence of SARS-CoV-2 antibodies during the third wave of COVID-19 in the Seoul metropolitan area of Korea.

OBJECTIVES: After the third wave of coronavirus disease 2019 (COVID-19), by mid-February 2021, approximately 0.16% of the Korean population was confirmed positive, which appeared to be among the lowest rates worldwide at that time. However, asymptomatic transmission is challenging for COVID-19 surveillance. Therefore, a community-based serosurvey of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was conducted to understand the effectiveness of Korea's strong containment strategy. METHODS: We collected 5,002 residual sera samples from January 30 to March 3, 2021, from 265 medical facilities in Seoul, 346 in Gyeonggi Province, and 57 in Incheon. Sixty samples from tertiary institutions were excluded. We defined the sub-regions according to the addresses of the medical facilities where the specimens were collected. Elecsys Anti-SARS-CoV-2 was used for screening, and positivity was confirmed using the SARS-CoV-2 sVNT Kit. Prevalence was estimated using sampling weights and the Wilson score interval for a binomial proportion with a 95% confidence interval. RESULTS: Among the 4,942 specimens, 32 and 25 tested positive for COVID-19 in the screening and confirmatory tests, respectively. The overall crude prevalence of SARS-CoV-2 antibodies was 0.51%. The population-adjusted overall prevalence was 0.55% in women and 0.38% in men. The region-specific estimation was 0.67% and 0.30% in Gyeonggi Province and Seoul, respectively. No positive cases were detected in Incheon. CONCLUSIONS: The proportion of undetected cases in Korea remained low as of early 2021. Therefore, an infection control strategy with exhaustive tracing and widespread pre-emptive testing appears to be effective in containing community spread of COVID-19.

Virus-like particles coexpressing the PreF and Gt antigens of respiratory syncytial virus confer protection in mice.

Aims: The purpose of this study was to assess the protective efficacy of virus-like particles (VLPs) co-expressing the pre-fusogenic (PreF) and G protein with tandem repeats (Gt) antigens of respiratory syncytial virus (RSV) in mice. Materials & methods: VLP constructs expressing PreF, Gt or both were used to immunize mice, and the protective efficacies were evaluated using antibody responses, neutralizing antibody titers, T-cell responses, histopathological assessment and plaque assay. Results: PreF+Gt VLP immunization elicited strong RSV-specific antibody responses and pulmonary T-cell responses that contributed to lessening virus titer and inflammation. Conclusion: Our findings suggest that coexpressing PreF and Gt antigens elicits better protection than either one alone. This combinatorial approach could assist in future RSV vaccine development.

Salivary testosterone in male and female youth with and without autism spectrum disorder: considerations of development, sex, and diagnosis.

BACKGROUND: Puberty is characterized by significant physical, hormonal, and psychological changes, which may be especially challenging for individuals with autism spectrum disorder (ASD). Although the etiology of ASD remains uncertain, studies suggest imbalances in hormones, such as testosterone, may modulate the autism phenotype. While differences in fetal and postnatal testosterone have been reported, there is limited literature regarding testosterone variations during adolescence in ASD. We investigated morning salivary testosterone levels in youth with ASD and typical development (TD) to explore hypothesized differences, expecting elevated hormonal levels in ASD compared to TD. METHODS: Youth with ASD (n = 140) and TD (n = 104), ages 10 to 13 years, were enrolled as part of a longitudinal study on pubertal development. Pubertal stage was determined by gold standard physical examination, and salivary testosterone was collected in the morning immediately upon waking and 30 min after waking and averaged across 3 days. Diagnostic (ASD/TD) and sex (male/female) differences, as well as interactions with age and puberty, were examined using robust linear mixed effect models. RESULTS: Youth with ASD showed significantly elevated testosterone concentrations compared to same-age TD peers. After the inclusion of natural cubic splines to account for nonlinearity in age, a significant age-by-sex interaction emerged with distinct developmental slopes for males and females. At younger ages, females had higher testosterone, until about 11.5 years of age, when levels began to plateau, while male testosterone concentrations continued to rapidly increase and surpass females. As expected, more advanced pubertal development was associated with elevated testosterone. In contrast, no significant effect of parent-reported social communication symptoms was observed. LIMITATIONS: Limitations include an unequal sex distribution, non-representative sample (e.g., cognition and race/ethnicity), and inability to examine afternoon/evening testosterone due to detection limits. CONCLUSIONS: Testosterone may play a unique role in the presentation of ASD, especially during periods of dynamic hormonal changes including puberty. Inherent developmental (age, puberty) and sex-based (male, female) factors play a more prominent role in changes in testosterone levels during adolescence. Even so, future research is warranted to determine the differential expression and impact of exposure to excess testosterone during the pubertal transition for youth with ASD.

Site-Level Comprehensiveness of Care Is Associated with Individual Clinical Retention Among Adults Living with HIV in International Epidemiology Databases to Evaluate AIDS, a Global HIV Cohort Collaboration, 2000-2016.

Retention in care (RIC) reduces HIV transmission and associated morbidity and mortality. We examined whether delivery of comprehensive services influenced individual RIC within the International epidemiology Databases to Evaluate AIDS (IeDEA) network. We collected site data through IeDEA assessments 1.0 (2000-2009) and 2.0 (2010-2016). Each site received a comprehensiveness score for service availability (1 = present, 0 = absent), with tallies ranging from 0 to 7. We obtained individual-level cohort data for adults with at least one visit from 2000 to 2016 at sites responding to either assessment. Person-time was recorded annually, with RIC defined as completing two visits at least 90 days apart in each calendar year. Multivariable modified Poisson regression clustered by site yielded risk ratios and predicted probabilities for individual RIC by comprehensiveness. Among 347,060 individuals in care at 122 sites with 1,619,558 person-years of follow-up, 69.8% of person-time was retained in care, varying by region from 53.8% (Asia-Pacific) to 82.7% (East Africa); RIC improved by about 2% per year from 2000 to 2016 (p = 0.012). Every site provided CD4+ count testing, and >90% of individuals received care at sites that provided combination antiretroviral therapy adherence measures, prevention of mother-to-child transmission, tuberculosis screening, HIV-related prevention, and community tracing services. In adjusted models, individuals at sites with more comprehensive services had higher probabilities of RIC (0.71, 0.74, and 0.83 for scores 5, 6, and 7, respectively; p = 0.019). Within IeDEA, greater site-level comprehensiveness of services was associated with improved individual RIC. Much work remains in exploring this relationship, which may inform HIV clinical practice and health systems planning.

Examination of pubertal timing and tempo in females and males with autism spectrum disorder compared to typically developing youth.

Autism spectrum disorder (ASD) is characterized by impaired social communication and poor adaptation to change; thus, pubertal development may be precarious. Pubertal timing and tempo were measured in 244 youth (7.9% Black, 83.3% White, and 8.7% multiracial) with ASD (N = 140) and typical development (N = 104). Pubertal development was measured using Tanner staging of Genital (G, males), Breast (B, females), and pubic hair (PH) in both sexes at Year 1 (10-13 years), Year 2 (11-14 years), and Year 3 (12-15 years). Nonlinear mixed effects models analyzed interindividual differences in timing and tempo. For both sexes, ASD and higher body mass index were associated with earlier pubertal timing. Males generally exhibited faster tempo than females. Linear regression models did not show associations between pubertal timing and internalizing symptoms at time three. Findings showing advanced pubertal maturation in ASD youth suggest greater risk of psychological, social, and physiological challenges. LAY SUMMARY: Youth with ASD have difficulty in social communication and adaption to change, thus puberty may be a challenging transition. The study examined onset (timing) and progression (tempo) of puberty over three years, using physical exam, in 244 adolescents with and without ASD, enrolled at ages 10-13. ASD youth started puberty earlier, while males generally progressed at a faster pace. Further examination of puberty in ASD should identify impact on social, behavioral, and mental health outcomes.

Comparison of plaque reduction and focus reduction neutralization tests for the measurement of neutralizing antibody titers against japanese encephalitis virus.

Japanese encephalitis is prevalent throughout the temperate and tropical regions of Asia and is caused by the Japanese encephalitis virus (JEV), a mosquito-borne viral pathogen. The plaque reduction neutralization test (PRNT) is currently recommended as the gold standard test for detecting human antibodies against JEV. The plaque assay is the most widely used method for detecting infectious virions and involves counting discrete plaques in cells. However, it is time-consuming, and results can be subjective (owing to analyst variability during manual plaque counting). The focus reduction neutralization test (FRNT), which is based on an immuno-colorimetric assay, can be used to automatically count foci formed by the JEV. Here, we compared the efficacy of PRNT and FRNT in measuring the neutralizing antibody titers using 102 serum samples from vaccinated and unvaccinated individuals. We observed positive correlations between these neutralization assays against the Nakayama and Beijing strains (R2 = 0.98 and 0.77, respectively). Thus, FRNT may be preferable to PRNT for evaluating the efficacy of JEV vaccines in large-scale serological studies.

SARS-CoV-2 Virus Dynamics in Recently Infected People-Data From a Household Transmission Study.

We used daily real-time reverse-transcription polymerase chain reaction (RT-PCR) results from 67 cases of SARS-CoV-2 infection in a household transmission study, conducted April 2020-May 2021, to examine the trajectory of cycle threshold (Ct) values, an inverse correlate of viral RNA concentration. Ct values varied across RT-PCR platforms and by participant age. Specimens collected from children and adolescents had higher Ct values and adults aged ≥50 years showed lower Ct values than adults aged 18-49 years. Ct values were lower on days when participants reported experiencing symptoms, with the lowest Ct value occurring 2-6 days after symptom onset.

Comparison of the Prevalence of Antibodies to SARS-CoV-2 in 9954 Recruits in the Korean Army Training Center with the General Korean Population of Equivalent Age Between September and November, 2020.

BACKGROUND Understanding the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be a useful tool when studying spread of the disease. This study aimed to compare the prevalence of antibodies to SARS-CoV-2 in 9954 recruits in the Korean Army Training Center with the general Korean population age <30 years between September and November, 2020. MATERIAL AND METHODS At the Korean Army Training Center, samples were taken from 9954 men from September to November, 2020. Participants were randomly enlisted healthy adult men. The data were compared with 4,205,265 samples from the Korean general population. Men age <30 years were used, as this is similar to the age range of the military recruits. RESULTS Among military recruits, 31 subjects (0.31%) were positive for the antibody, while the Korean male population had 3757 (0.09%) positive individuals. Among these 31 men, 13 were previously diagnosed by PCR, while 18 (58.06%) had no history related to the disease. Positive military recruits were mostly from 2 regional clusters. The first cluster was Daegu and Gyeongbuk areas (1.97% and 0.80%, respectively), which had an outbreak in March, 2020. The second cluster was Gyeonggi and Seoul, or capital areas (0.23% and 0.20%, respectively), which currently has high PCR positivity. Overall, seroprevalence was 3.49 times higher in study subjects. CONCLUSIONS The high seroprevalence of antibodies to SARS-CoV-2 between September and November 2020 in a densely populated military academy in Korea may have been an indicator for the resulting outbreak of COVID-19 in winter 2020-21, which highlights the importance of asymptomatic spread from the young and healthy to the general population.

Heterologous ChAdOx1 and Bnt162b2 vaccination induces strong neutralizing antibody responses against SARS-CoV-2 including delta variant with tolerable reactogenicity.

OBJECTIVES: We assessed humoral responses and reactogenicity following the heterologous vaccination compared to the homologous vaccination groups. METHODS: We enrolled healthcare workers (HCWs) who were either vaccinated with ChAdOx1 followed by BNT162b2 (heterologous group) or 2 doses of ChAdOx1 (ChAdOx1 group) or BNT162b2 (BNT162b2 group). Immunogenicity was assessed by measuring antibody titers against receptor-binding domain (RBD) of SARS-CoV-2 spike protein in all participants and neutralizing antibody titer in 100 participants per group. Reactogenicity was evaluated by a questionnaire-based survey. RESULTS: We enrolled 499 HCWs (ChAdOx1, n = 199; BNT162b2, n = 200; heterologous ChAdOx1/BNT162b2, n = 100). The geometric mean titer of anti-receptor-binding domain antibody at 14 days after the booster dose was significantly higher in the heterologous group (11 780.55 binding antibody unit (BAU)/mL [95% CI, 10 891.52-12 742.14]) than in the ChAdOx1 (1561.51 [95% CI, 1415.03-1723.15]) or BNT162b2 (2895.90 [95% CI, 2664.01-3147.98]) groups (both p < 0.001). The neutralizing antibody titer of the heterologous group (geometric mean ND50, 2367.74 [95% CI, 1970.03-2845.74]) was comparable to that of the BNT162b2 group (2118.63 [95% CI, 1755.88-2556.32]; p > 0.05) but higher than that of the ChAdOx1 group (391.77 [95% CI, 326.16-470.59]; p < 0.001). Compared with those against wild-type SARS-CoV-2, the geometric mean neutralizing antibody titers against the Delta variant at 14 days after the boosting were reduced by 3.0-fold in the heterologous group (geometric mean ND50, 872.01 [95% CI, 685.33-1109.54]), 4.0-fold in the BNT162b2 group (337.93 [95% CI, 262.78-434.57]), and 3.2-fold in the ChAdOx1 group (206.61 [95% CI, 144.05-296.34]). The local or systemic reactogenicity after the booster dose in the heterologous group was higher than that of the ChAdOx1 group but comparable to that of the BNT162b2 group. DISCUSSION: Heterologous ChAdOx1 followed by BNT162b2 vaccination with a 12-week interval induced a robust humoral immune response against SARS-CoV-2, including the Delta variant, that was comparable to the homologous BNT162b2 vaccination and stronger than the homologous ChAdOx1 vaccination, with a tolerable reactogenicity profile.