OBJECTIVE: The specific humoral immune response resulting from inactivated vaccination following by BA.5 infection, and predictors of XBB variants re-infection in BA.5 infection-recovered nasopharyngeal carcinoma (BA.5-RNPC) patients, were explored.
METHODS: Serum SARS-CoV-2 specific antibody levels were assessed using enzyme-linked-immunosorbent-assay. Univariate and multivariate binary logistic regression analyses were conducted to identify factors associated with the magnitude of specific humoral immunity and susceptibility to re-infection by XBB variants.
RESULTS: Our data demonstrates that SARS-CoV-2 specific antibody levels were comparable between BA.5-RNPC patients and BA.5 infection-recovered-non-cancerous (BA.5-RNC) individuals. Specifically, serum levels of anti-ancestral-S1-IgG, anti-ancestral-nucleocapsid-protein (NP)-IgG, anti-BA.5-receptor binding domain (RBD)-IgG and anti-XBB.1.1.6-RBD-IgG were higher in BA.5-RNPC patients compared to those without a prior infection. Compared to BA.5-RNPC patients without vaccination, individuals who received inactivated vaccination exhibited significantly higher levels of anti-ancestral-S1-IgG and anti-XBB.1.16-RBD-IgG. Multivariate logistic regression analysis revealed that inactivated vaccination was the most significant predictor of all tested SARS-CoV-2 specific antibodies response. Subsequent analysis indicated that a low globulin level is an independent risk factor for XBB re-infection in BA.5-RNPC patients.
CONCLUSIONS: The SARS-CoV-2 specific antibodies have been improved in vaccinated BA.5-RNPC patients. However, the baseline immunity status biomarker IgG is an indicators of XBB variant re-infection risk in BA.5-RNPC patients.

UNASSIGNED: This study investigated the epidemiological and clinical characteristics of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infected patients during the second pandemic of COVID-19 (coronavirus disease of 2019) in Chengdu, China. Furthermore, the differences between first infection and re-infection cases were also compared and analyzed to provide evidence for better prevention and control of SARS-CoV-2 re-infection.
UNASSIGNED: An anonymous questionnaire survey was conducted using an online platform (wjx.cn) between May 20, 2023 to September 12, 2023.
UNASSIGNED: This investigation included 62.94% females and 32.97% of them were 18-30 years old. Furthermore, 7.19-17.18% of the participants either did not receive vaccination at all or only received full vaccination, respectively. Moreover, 577 (57.64%) participants were exposed to cluster infection. The clinical manifestations of these patients were mainly mild to moderate; 78.18% of participants had a fever for 1-3 days, while 37.84% indicated a full course of disease for 4-6 days. In addition, 40.66% of the participants had re-infection and 72.97% indicated their first infection approximately five months before. The clinical symptoms of the first SARS-CoV-2 infection were moderate to severe, while re-infection indicated mild to moderate symptoms (the severity of symptoms other than diarrhea and conjunctival congestion had statistically significant differences) (p < 0.05). Moreover, 70.53 and 59.21% of first and re-infection cases had fever durations of 3-5 and 0-2 days, respectively. Whereas 47.91 and 46.40% of first and re-infection cases had a disease course of 7-9 and 4-6 days.
UNASSIGNED: The SARS-CoV-2 infected individuals in Chengdu, China, during the second pandemic of COVID-19 had mild clinical symptoms and a short course of disease. Furthermore, compared with the first infection, re-infection cases had mild symptoms, low incidences of complications, short fever duration, and course of disease.

We propose new single and two-strain epidemic models represented by systems of delay differential equations and based on the number of newly exposed individuals. Transitions between exposed, infectious, recovered, and back to susceptible compartments are determined by the corresponding time delays. Existence and positiveness of solutions are proved. Reduction of delay differential equations to integral equations allows the analysis of stationary solutions and their stability. In the case of two strains, they compete with each other, and the strain with a larger individual basic reproduction number dominates the other one. However, if the basic reproduction number exceeds some critical values, stationary solution loses its stability resulting in periodic time oscillations. In this case, both strains are present and their dynamics is not completely determined by the basic reproduction numbers but also by other parameters. The results of the work are illustrated by comparison with data on seasonal influenza.

The COVID-19 pandemic has become a global health crisis, inflicting substantial morbidity and mortality worldwide. A diverse range of symptoms, including fever, cough, dyspnea, and fatigue, characterizes COVID-19. A cytokine surge can exacerbate the disease\'s severity. This phenomenon involves an increased immune response, marked by the excessive release of inflammatory cytokines like IL-6, IL-8, TNF-α, and IFNγ, leading to tissue damage and organ dysfunction. Efforts to reduce the cytokine surge and its associated complications have garnered significant attention. Standardized management protocols have incorporated treatment strategies, with corticosteroids, chloroquine, and intravenous immunoglobulin taking the forefront. The recent therapeutic intervention has also assisted in novel strategies like repurposing existing medications and the utilization of in vitro drug screening methods to choose effective molecules against viral infections. Beyond acute management, the significance of comprehensive post-COVID-19 management strategies, like remedial measures including nutritional guidance, multidisciplinary care, and follow-up, has become increasingly evident. As the understanding of COVID-19 pathogenesis deepens, it is becoming increasingly evident that a tailored approach to therapy is imperative. This review focuses on effective treatment measures aimed at mitigating COVID-19 severity and highlights the significance of comprehensive COVID-19 management strategies that show promise in the battle against COVID-19.

Since its inception in December 2019, many safe and effective vaccines have been invented and approved for use against COVID-19 along with various non-pharmaceutical interventions. But the emergence of numerous SARS-CoV-2 variants has put the effectiveness of these vaccines, and other intervention measures under threat. So it is important to understand the dynamics of COVID-19 in the presence of its variants of concern (VOC) in controlling the spread of the disease. To address these situations and to find a way out of this problem, a new mathematical model consisting of a system of non-linear differential equations considering the original COVID-19 strain with its two variants of concern (Delta and Omicron) has been proposed and formulated in this paper. We then analyzed the proposed model to study the transmission dynamics of this multi-strain model and to investigate the consequences of the emergence of multiple new SARS-CoV-2 variants which are more transmissible than the previous ones. The control reproduction number, an important threshold parameter, is then calculated using the next-generation matrix method. Further, we presented the discussion about the stability of the model equilibrium. It is shown that the disease-free equilibrium (DFE) of the model is locally asymptotic stable when the control reproduction is less than unity. It is also shown that the model has a unique endemic equilibrium (EEP) which is locally asymptotic stable when the control reproduction number is greater than unity. Using the Center Manifold theory it is shown that the model also exhibits the backward bifurcation phenomenon when the control reproduction number is less than unity. Again without considering the re-infection of the recovered individuals, it is proved that the disease-free equilibrium is globally asymptotically stable when the reproduction threshold is less than unity. Finally, numerical simulations are performed to verify the analytic results and to show the impact of multiple new SARS-CoV-2 variants in the population which are more contagious than the previous variants. Global uncertainty and sensitivity analysis has been done to identify which parameters have a greater impact on disease dynamics and control disease transmission. Numerical simulation suggests that the emergence of new variants of concern increases COVID-19 infection and related deaths. It also reveals that a combination of non-pharmaceutical interventions with vaccination programs of new more effective vaccines should be continued to control the disease outbreak. This study also suggests that more doses of vaccine should provide to combat new and deadly variants like Delta and Omicron.

BACKGROUND: Like its predecessors in the XBB family, XBB.1.5 is highly immune evasive from therapeutic monoclonal antibodies and neutralizing antibodies generated by vaccination and/or infection. However, there is a lack of in vivo data on XBB.1.5 in animal models such as Syrian hamsters.
METHODS: Syrian hamsters (females) were used to examine airborne transmission along with virus replication of XBB.1.5 in naïve animals and human ACE2 hamsters with pre-existing immunity from a previous infection with Omicron BA.1. Assays were performed to determine neutralizing antibody responses, and virus titers were determined by standard plaque assays.
RESULTS: Unlike earlier Omicron subvariants, such as BA.1 and BA.2, XBB.1.5 transmitted more efficiently in the hamster model. In addition, XBB.1.5 partially escaped BA.1-immunity from a previous infection with XBB.1.5 replicating in the nasal turbinate tissues and to a lesser extend in the lung tissues of previously infected hamsters.
CONCLUSIONS: Our in vivo data showing better airborne transmissibility of the Omicron subvariant XBB.1.5 than its predecessor, BA.2, in Syrian hamsters will allow researchers to further investigate amino acid substitutions that give XBB.1.5 a fitness advantage over BA.2 in transmission, data that may be important in studies of SARS-CoV-2 transmission in humans.
BACKGROUND: This research is supported by grants from the Center for Research on Influenza Pathogenesis and Transmission (CRIPT; 75N93021C00014), funded by the National Institute of Allergy and Infectious Diseases and by a Research Program on Emerging and Reemerging Infectious Diseases (JP21fk0108552 and JP21fk0108615), a Project Promoting Support for Drug Discovery (JP21nf0101632), the Japan Program for Infectious Diseases Research and Infrastructure (JP22wm0125002), and The University of Tokyo Pandemic Preparedness, Infection and Advanced Research Center (UTOPIA) grant (JP223fa627001) from the Japan Agency for Medical Research and Development.

BACKGROUND: Surgical site infection (SSI) is a common complication following orthopedic implantation. We developed an iodine coating for titanium implants to reduce implant-related infections and conducted a prospective clinical study to evaluate the efficacy and potential drawbacks of iodine-supported implants.
METHODS: Between July 2008 and July 2017, 653 patients (377 male and 27 female patients; mean age, 48.6) with postoperative infection or a compromised status were treated using iodine-loaded titanium implants. The mean follow-up period was 41.7 months. In 477 patients, iodine-supported implants were used to prevent infection and in 176 patients, to treat active infection (one-stage surgery, 89 patients; two-stage surgery, 87 patients). In the limbs and pelvis, the primary diagnoses included the following: 161 tumors, 92 deformities/shortening, 47 pseudarthrosis, 42 fractures, 32 infected TKA, 25 osteoarthritis, 21 pyogenic arthritis, 20 infected THA, and 6 osteomyelitis. In the spinal cases, there were 136 cases of tumors, 36 cases of pyogenic spondylitis, and 35 cases of degeneration. Five modes of implant failure were identified and classified as follows: soft tissue failure (type 1), aseptic loosening (type 2), structural failure (type 3), infection (type 4), and tumor progression (type 5).
RESULTS: The overall failure rate in our series was 26.3% (172/653). There were 101 mechanical failures, including 22 type 1, 20 type 2, and 59 type 3 failures. Non-mechanical causes accounted for 71 failures, including 45 type 4 and 26 type 5 failures. The overall incidence of infections was 6.8%. The mean time to the onset of infection after implantation was 9.1 months. The overall infection rate was 3.7% in the prevention cases and 15.3% in the treatment cases. There was no difference between one-stage replacement (14.6%) and two-stage replacement (16.0%). There were 11 cases of treatment for SSI of spine surgery, and the re-infection rate was 0% using iodine-coated instruments.
CONCLUSIONS: The five modes of failure of the iodine-supported implant were satisfactory compared with previous reports. In particular, because the infection rate of iodine-coated implants used for compromised hosts is low compared with other methods, postoperative infection is more easily controlled. It can be considered highly effective for spinal infections that require one-stage revision surgery.
METHODS: Trial registration Prospective, Observation study.

Highly effective direct-acting antiviral (DAA) agents have changed the landscape of hepatitis C virus infection (HCV) treatment and have become more available to people who inject drugs (PWID) over the past several years. Although many achieve a sustained virologic response (SVR), a small proportion will become re-infected. This study examined experiences of re-infection among participants in Project HERO, a large multi-site treatment trial designed to test alternative treatment delivery models for DAAs.
Study staff conducted qualitative interviews with twenty-three HERO participants who experienced reinfection following successful treatment for HCV. Interviews focused on life circumstances and experiences with treatment/re-infection. We conducted a thematic analysis, followed by a narrative analysis.
Participants described challenging life circumstances. The initial experience of cure was joyful, leading participants to feel that they had escaped a defiled, stigmatized identity. Re-infection was very painful. Feelings of shame were common. Participants with fully developed narratives of re-infection described both a strong emotional response as well as a plan for avoiding re-infection during retreatment. Participants who lack such stories showed signs of hopelessness and apathy.
Though the promise of personal transformation through SVR may be motivating for patients, clinicians should be cautious about how they describe the \"cure\" when educating patients about HCV treatment. Patients should be encouraged to avoid stigmatizing, dichotomizing language of the self, including terms such as \"dirty\" and \"clean.\" In acknowledging the benefits of HCV cure, clinicians should emphasize that re-infection does not mean failed treatment; and that current treatment guidelines support retreatment of re-infected PWID.

Chlamydia trachomatis (chlamydia) is one of the most common sexually transmitted infections (STI) globally, and re-infections are common. Current Australian guidelines recommend re-testing for chlamydia 3 months after treatment to identify possible re-infection. Patient-delivered partner therapy (PDPT) has been proposed to control chlamydia re-infection among heterosexuals. We aimed to identify determinants and the prediction of chlamydia re-testing and re-infection within 1 year among heterosexuals with chlamydia to identify potential PDPT candidates.
Our baseline data included 5,806 heterosexuals with chlamydia aged ≥18 years and 2,070 re-tested for chlamydia within 1 year of their chlamydia diagnosis at the Melbourne Sexual Health Center from January 2, 2015, to May 15, 2020. We used routinely collected electronic health record (EHR) variables and machine-learning models to predict chlamydia re-testing and re-infection events. We also used logistic regression to investigate factors associated with chlamydia re-testing and re-infection.
About 2,070 (36%) of 5,806 heterosexuals with chlamydia were re-tested for chlamydia within 1 year. Among those retested, 307 (15%) were re-infected. Multivariable logistic regression analysis showed that older age (≥35 years old), female, living with HIV, being a current sex worker, patient-delivered partner therapy users, and higher numbers of sex partners were associated with an increased chlamydia re-testing within 1 year. Multivariable logistic regression analysis also showed that younger age (18-24 years), male gender, and living with HIV were associated with an increased chlamydia re-infection within 1 year. The XGBoost model was the best model for predicting chlamydia re-testing and re-infection within 1 year among heterosexuals with chlamydia; however, machine learning approaches and these self-reported answers from clients did not provide a good predictive value (AUC < 60.0%).
The low rate of chlamydia re-testing and high rate of chlamydia re-infection among heterosexuals with chlamydia highlights the need for further interventions. Better targeting of individuals more likely to be re-infected is needed to optimize the provision of PDPT and encourage the test of re-infection at 3 months.

BACKGROUND: Urogenital schistosomiasis is a neglected tropical disease most prevalent in sub-Saharan Africa. In the Senegal river basin, the construction of the Diama dam led to an increase and endemicity of schistosomiasis. Since 2009, praziquantel has frequently been used as preventive chemotherapy in the form of mass administration to Senegalese school-aged children without monitoring of the treatment efficacy and the prevalence after re-infection. This study aims to determine the current prevalence of urogenital schistosomiasis (caused by Schistosoma haematobium), the efficacy of praziquantel, and the re-infection rates in children from five villages with different water access.
METHODS: The baseline prevalence of S. haematobium was determined in August 2020 in 777 children between 5 and 11 years old and a single dose of praziquantel (40 mg/kg) was administered to those positive. The efficacy of praziquantel and the re-infection rates were monitored 4 weeks and 7 months after treatment, respectively, in 226 children with a high intensity of infection at baseline.
RESULTS: At the baseline, prevalence was low among children from the village of Mbane who live close to the Lac de Guiers (38%), moderate among those from the villages of Dioundou and Khodit, which neighbor the Doue river (46%), and very high at Khodit (90.6%) and Guia (91.2%) which mainly use an irrigation canal. After treatment, the observed cure rates confirmed the efficacy of praziquantel. The lowest cure rate (88.5%) was obtained in the village using the irrigation canal, while high cure rates were obtained in those using the lake (96.5%) and the river (98%). However, high egg reduction rates (between 96.7 and 99.7%) were obtained in all the villages. The re-infection was significantly higher in the village using the canal (42.5%) than in the villages accessing the Lac de Guiers (18.3%) and the Doue river (14.8%).
CONCLUSIONS: Praziquantel has an impact on reducing the prevalence and intensity of urogenital schistosomiasis. However, in the Senegal river basin, S. haematobium remains a real health problem for children living in the villages near the irrigation canals, despite regular treatment, while prevalence is declining from those frequenting the river and the Lac de Guiers. Trial registration ClinicalTrials.gov, NCT04635553. Registered 19 November 2020 retrospectively registered, https://www.
RESULTS: gov/ct2/show/NCT04635553?cntry=SN&draw=2&rank=4.