[Intramedullary nailing of coated and uncoated nails in infected tibial pseudarthrosis : Results of a retrospective examination of 56 patients]. / Intramedulläre Nagelung von beschichteten und unbeschichteten Nägeln bei Tibia-Infektpseudarthrosen : Ergebnisse einer retrospektiven Untersuchung von 56 Patienten.

BACKGROUND: In surgery for sepsis it is a well-established principle that no internal osteosynthetic material should be implanted in cases of chronic osteomyelitis. Therefore, the surgical treatment with intramedullary nails is so far used only rarely in cases of chronic osteomyelitis. OBJECTIVE: This study analyzed whether the implantation of tibial intramedullary nails is an effective treatment for chronic osteomyelitis and how high is the rate of reinfection. MATERIAL AND METHODS: A retrospective analysis of patients with an infected pseudarthrosis of the tibia in whom a gentamycin-coated nail (ETN) or an uncoated tibial intramedullary nail (UCN) was implanted between December 2011 and December 2019 was carried out. The preoperative, perioperative and postoperative results were evaluated. RESULTS: During the study period 29 patients received a UCN and 27 patients received an ETN. Of the patients 95% (n = 53) had been previously unsuccessfully treated with external fixation. Postoperative complications occurred in 45% of the patients and more often in the ETN group (48% vs. 41%). Reexacerbation of the infection occurred in 20 patients and more frequently in the UCN group (38% vs. 33%). The nonunion already showed a bony consolidation at the time of the exacerbation in 10 patients (50%). At the end of the follow-up a consolidation was present in 48 patients (86%), more frequently in the UCN group (90% vs. 78%). Of the patients 50 (89%) reached full weight bearing without any differences between the groups. CONCLUSION: Despite a relatively high a rate of postoperative complications the risk of reinfection was acceptable with good functional and radiological results. The main general advantages of nailing are without doubt the high primary stability, the implantation with preservation of the soft tissue and the improved wearing comfort for patients.

COVID-19 Disease Incidence and Severity in Previously Infected Unvaccinated Compared with Previously Uninfected Vaccinated Persons.

Using the VA COVID-19 National Database, we created matched pairs of previously uninfected vaccinated (≥2 doses of an mRNA vaccine) and previously infected unvaccinated individuals. The incidence rate (per 1000 person-days) of breakthrough infection among vaccinated individuals (0.30, 95% CI 0.29-0.32) was similar to reinfection rate among unvaccinated individuals (0.31, 95% CI 0.30-0.32; p=0.5). The incidence rate of hospitalization/death was higher after reinfection (7.31, 95% CI 6.66-8.03) compared with rate after breakthrough infection (4.69, 95% CI 4.06-5.42; P<0.0001). Conclusion: The incidence of hospitalization/death is significantly higher after reinfection among unvaccinated individuals compared with breakthrough infection after vaccination.

Ad5-nCoV boosted vaccine and reinfection-induced memory T/B cell responses and humoral immunity to SARS-CoV-2: based on two prospective cohorts.

AbstractHere, we regularly followed SARS-CoV-2 infected cohorts to investigate the combined effects of neutralizing antibodies (NAbs) and B and T cell profiles during the convalescent period. Ten participants infected with SARS-CoV-2 in December 2022 were selected to assess the effects of an inhaled adenovirus type 5 vectored COVID-19 vaccine (Ad5-nCoV) booster on B cells and humoral immunity. To evaluate T cell responses, eight primary and 20 reinfection participants were included. Blood samples from all 38 participants were collected at 1-, 2-, and 6-months post-infection. The assays included single B cell technology, activation-induced marker (AIM) assays, and pseudovirus neutralization. In the first cohort, eighteen monoclonal antibodies (mAbs) with neutralizing activity from memory B cells (MBC) against SARS-CoV-2 mutants were obtained by high throughput single-B-cell cloning method, which lasted from 1- month to 6- month post infection. The overall number of mAbs from MBC in the inhaled Ad5-nCoV-boosted immunization group was higher than that in the non-boosted immunization group at 2-, and 6-months post-infection. In the second cohort, circulating T follicular helper cells (cTfh) and AIM + CD4 + T cells increased over time in the reinfection group (P < 0.05). The serum NAb levels against XBB.1.22, EG.5.1, and JN.1 in the primary infection group tended to increase from the post 1-month to 2-month infection (P < 0.05). In both cohorts, serum NAb titers showed significant immune escape, while cTfh and AIM + CD4 + T cells in the second cohort essentially showed no immune escape to new strains (including XBB, EG.5) during the six-month follow-up period. AIM + CD4 + T cells against BA.5 and EG.5 were strongly negatively correlated with the time to viral clearance in the reinfected group after months of 6M infection. The broader significance of this study was to comprehensively assess the ability of the SARS-CoV-2 boosted immunization and reinfection-induced generation of T/B cell immune memories in preventing reinfection.

Estimation of outpatient SARS-CoV-2 reinfection and recurrence rates and associated factors among COVID-19 hospitalized patients over one-year old: a multicenter retrospective cohort study.

INTRODUCTION: Reinfection with SARS-Cov-2 after recovery can occur that most of them don't require hospitalization. The aim of this study is estimation of out-patient COVID-19 reinfection and recurrence rates and its associated factors among Iranian patients with history of confirmed SARS-Cov-2 infection and hospitalization. METHODS: This study is a retrospective cohort conducted from May 2021 to May 2022 in Iran. The national Medical Care Monitoring Center (MCMC) database, obtained from the Ministry of Health and Medical Education, includes all information about confirmed COVID-19 patients who are hospitalized and diagnosed during the pandemic. Using probability proportional to size sampling from 31 provinces, 1,532 patients over one years of age with a history of hospitalization in the MCMC data are randomly selected. After that, interviews by phone are performed with all of the selected patients using a researcher-made questionnaire about the occurrence of overall reinfection without considering the time of infection occurrence, reinfection occurring at least 90 days after the discharge and recurrence (occurring within 90 days after discharge). Univariate and multivariable Cox regression analyses are performed to assess the factors associated with each index. All of the analyses are performed using Stata software version 16. RESULTS: In general, 1,532 phone calls are made, out of which 1,095 individuals are willing to participate in the study (response rate ≃ 71%). After assessing the 1,095  patients with a positive history of COVID-19, the rates of non-hospitalized overall SARS-Cov-2 reinfection, reinfection and recurrence are 122.64, 114.09, and 8.55 per 1,000 person-years, respectively. The age range of 19-64 years (aHR:3.93, 95%CI : 1.24-12.41) and COVID-19-related healthcare worker (aHR: 3.67, 95%CI: 1.77-7.61) are identified as risk factors for reinfection, while having comorbidity, being fully vaccinated, and having a partial pressure of oxygen (PaO2) ≥ 93 mmHg during the initial infection are identified as factors that reduce the risk of non-hospitalized reinfection. CONCLUSION: Reinfection due to COVID-19 is possible because of the weakened immune system for various reasons and the mutation of the virus. Vaccination, timely boosters, and adherence to preventive measures can help mitigate this risk.

SARS-CoV-2 Seropositivity in Nursing Home Staff and Residents during the First SARS-CoV-2 Wave in Flanders, Belgium.

(1) Background: early in the COVID-19 pandemic, reverse transcription polymerase chain reaction (RT-PCR) testing was limited. Assessing seroprevalence helps understand prevalence and reinfection risk. However, such data are lacking for the first epidemic wave in Belgian nursing homes. Therefore, we assessed SARS-CoV-2 seroprevalence and cumulative RT-PCR positivity in Belgian nursing homes and evaluated reinfection risk. (2) Methods: we performed a cross-sectional study in nine nursing homes in April and May 2020. Odds ratios (ORs) were calculated to compare the odds of (re)infection between seropositive and seronegative participants. (3) Results: seroprevalence was 21% (95% CI: 18-23): 22% (95% CI: 18-25) in residents and 20% (95% CI: 17-24) in staff. By 20 May 2020, cumulative RT-PCR positivity was 16% (95% CI: 13-21) in residents and 8% (95% CI: 6-12) in staff. ORs for (re)infection in seropositive (compared to seronegative) residents and staff were 0.22 (95% CI: 0.06-0.72) and 3.15 (95% CI: 1.56-6.63), respectively. (4) Conclusion: during the first wave, RT-PCR test programmes underestimated the number of COVID-19 cases. The reinfection rate in residents was 3%, indicating protection, while it was 21% in staff, potentially due to less cautious health behaviour. Future outbreaks should use both RT-PCR and serological testing for complementary insights into transmission dynamics.

Meta-analysis of hybrid immunity to mitigate the risk of Omicron variant reinfection.

Background: Hybrid immunity (a combination of natural and vaccine-induced immunity) provides additional immune protection against the coronavirus disease 2019 (COVID-19) reinfection. Today, people are commonly infected and vaccinated; hence, hybrid immunity is the norm. However, the mitigation of the risk of Omicron variant reinfection by hybrid immunity and the durability of its protection remain uncertain. This meta-analysis aims to explore hybrid immunity to mitigate the risk of Omicron variant reinfection and its protective durability to provide a new evidence-based basis for the development and optimization of immunization strategies and improve the public's awareness and participation in COVID-19 vaccination, especially in vulnerable and at-risk populations. Methods: Embase, PubMed, Web of Science, Chinese National Knowledge Infrastructure, and Wanfang databases were searched for publicly available literature up to 10 June 2024. Two researchers independently completed the data extraction and risk of bias assessment and cross-checked each other. The Newcastle-Ottawa Scale assessed the risk of bias in included cohort and case-control studies, while criteria recommended by the Agency for Health Care Research and Quality (AHRQ) evaluated cross-sectional studies. The extracted data were synthesized in an Excel spreadsheet according to the predefined items to be collected. The outcome was Omicron variant reinfection, reported as an Odds Ratio (OR) with its 95% confidence interval (CI) and Protective Effectiveness (PE) with 95% CI. The data were pooled using a random- or fixed-effects model based on the I2 test. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. Results: Thirty-three articles were included. Compared with the natural immunity group, the hybrid immunity (booster vaccination) group had the highest level of mitigation in the risk of reinfection (OR = 0.43, 95% CI:0.34-0.56), followed by the complete vaccination group (OR = 0.58, 95% CI:0.45-0.74), and lastly the incomplete vaccination group (OR = 0.64, 95% CI:0.44-0.93). Compared with the complete vaccination-only group, the hybrid immunity (complete vaccination) group mitigated the risk of reinfection by 65% (OR = 0.35, 95% CI:0.27-0.46), and the hybrid immunity (booster vaccination) group mitigated the risk of reinfection by an additional 29% (OR = 0.71, 95% CI:0.61-0.84) compared with the hybrid immunity (complete vaccination) group. The effectiveness of hybrid immunity (incomplete vaccination) in mitigating the risk of reinfection was 37.88% (95% CI, 28.88-46.89%) within 270-364 days, and decreased to 33.23%% (95% CI, 23.80-42.66%) within 365-639 days; whereas, the effectiveness after complete vaccination was 54.36% (95% CI, 50.82-57.90%) within 270-364 days, and the effectiveness of booster vaccination was 73.49% (95% CI, 68.95-78.04%) within 90-119 days. Conclusion: Hybrid immunity was significantly more protective than natural or vaccination-induced immunity, and booster doses were associated with enhanced protection against Omicron. Although its protective effects waned over time, vaccination remains a crucial measure for controlling COVID-19. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/, identifier, CRD42024539682.

Correlates of Nucleocapsid Antibodies and a Combination of Spike and Nucleocapsid Antibodies Against Protection of SARS-CoV-2 Infection During the Omicron XBB.1.16/EG.5-Predominant Wave.

Background: We aimed to examine the association among nucleocapsid (N) antibodies, a combination of N and spike (S) antibodies, and protection against SARS-CoV-2 reinfection. Methods: We conducted a prospective cohort study among staff at a national medical research center in Tokyo and followed them for the incidence of SARS-CoV-2 infection between June and September 2023 (Omicron XBB.1.16/EG.5 wave). At baseline, participants donated blood samples to measure N- and S-specific antibodies. Cox regression was used to estimate the hazard ratio and protection ([1 - hazard ratio] × 100) against subsequent SARS-CoV-2 infection across these antibody levels. Results: Among participants with previous infection, higher pre-reinfection N antibodies were associated with a lower risk of reinfection, even after adjusting S antibody levels (P < .01 for trend). Estimation of the protection matrix for N and S antibodies revealed that high levels in N and S antibodies conferred robust protection (>90%) against subsequent infection. In addition, a pattern of low pre-reinfection N antibodies but high vaccine-enhanced S antibodies showed high protection (>80%). Conclusions: Pre-reinfection N antibody levels correlated with protection against reinfection, independent of S antibodies. If the N antibodies were low, vaccine-boosted S antibodies might enhance the reinfection protection.

Diagnostic approach to the etiology of recurrent pneumonia in children.

BACKGROUND: Recurrent pneumonia (RP) accounts for 7.7%-9% of childhood pneumonia. Identifying the cause of RP is crucial for infection control and reducing mortality and morbidity. This study aimed to investigate the etiology, risk factors, and diagnostic procedures of RP based on the literature using a diagnostic algorithm. METHODS: Our study included RP patients aged 0-18 years who were followed up as outpatients or inpatients between 2018 and 2021. Patients were analyzed retrospectively using the national health database. Patients with RP were identified by ICD diagnosis codes. Etiology and risk factors were determined based on the occurrence of RP in the same or different areas. RESULTS: The rate of RP was found to be 14.4% among the cases of recurrent lower respiratory tract infection. Of these, 27.6% occurred in the same area and 72.4% in different areas. The underlying etiology was identified in 224 of 250 RP patients (89.6%). RP in different areas was mainly due to neuromuscular diseases, whereas asthma, right middle lobe syndrome, and congenital lung or airway structural disease were common causes of RP in the same area. Malnutrition, passive smoke exposure, and prematurity were common risk factors in both groups. CONCLUSIONS: Systematic etiological investigations should take into account the characteristics of the patient population and geographical region. The use of diagnostic algorithms based on recurrence in the same or different areas is particularly beneficial. Whether asthma is causally related to RP episodes or is a coincidental association due to inadequate differential diagnosis remains unclear.

Specific persistent symptoms of COVID-19 and associations with reinfection: a community-based survey study in southern China.

Background: Surveillance remains fundamental to understanding the changes in epidemiological patterns regarding post-COVID conditions and reinfections. Persistent symptoms and reinfection in previously infected individuals are increasing being reported in many countries, but their associations among general populations were seldomly reported. Understanding the association with persistent symptoms of COVID-19 reinfection is essential to develop strategies to mitigate the long-term health and socio-economic impacts of the post-COVID conditions. This study aimed to investigate the incidence of COVID-19 persistent symptoms among previously infected Chinese community residents and explore associations of specific COVID-19 persistent symptoms with reinfection and other factors. Methods: A community-based survey was conducted in a southern city of China with about 20 million residents from August 3 to 24, 2023. Face-to-face questionnaires were distributed to a total of 1,485 residents to collect their information about COVID-19 infection, reinfection, specific ongoing persistent symptoms, and other COVID-19 related information. Multivariable logistic regression analysis was used to examine the association between specific persistent symptoms and reinfection of COVID-19, along with age, gender, and educational level. Results: Of the 1,485 participants, 1,089 (73.3%) reported they had been infected with COVID-19. Among them, 89.1% reported having ongoing persistent symptoms and 14.2% reported had two or more times of infection. About 20% participants were infected 1 year or more since their initial infection. Fatigue, cough, and headaches were the top 3 symptoms being reported. Participants with reinfection were associated with a higher probability of reporting headaches (OR: 1.54, 95% CI: 1.06-2.25), loss of or change in smell and/or taste (OR: 1.90, 95% CI: 1.27-2.83), impaired sleep (OR: 1.55, 95% CI: 1.02-2.35), and brain fog (OR: 1.76, 95% CI: 1.12-2.76). Participants aged 45 and above and who had a bachelor's or higher degree were more likely to report chest tightness or shortness of breath, impaired sleep, and brain fog. Discussion: During the post-emergency period of COVID-19 pandemic, the incidence of ongoing persistent symptoms among Chinese residents remains high. Individuals whose initial infection was longer than 1 year have the highest probability of reporting having multiple symptoms. Reinfection may increase the risk of reporting headaches, loss of or change in smell and/or taste, impaired sleep, and brain fog. It is important to maintain routine syndromic surveillance among previously infected people and provide recommendations for clinical management of individuals with multiple ongoing symptoms.

Rate and Risk Factors of Reinfection, Recurrence, and Hospital Readmission Among SARS-Cov-2 Hospitalized Patients; a National Cohort Study.

Introduction: Reinfection and hospital readmission due to COVID-19 were significant and costly during the pandemic. This study aimed to assess the rate and risk factors of SARS-Cov-2 reinfection, recurrence, and hospital readmission, by analyzing the national data registry in Iran. Methods: This study was a retrospective cohort conducted from March 2020 to May 2021. A census method was used to consider all of the possible information in the national Medical Care Monitoring Center (MCMC) database obtained from the Ministry of Health and Medical Education; the data included information from all confirmed COVID-19 patients who were hospitalized and diagnosed using at least one positive Polymerase Chain Reaction (PCR) test by nasopharyngeal swab specimens. Univariate and multivariable Cox regression analyses were performed to assess the factors related to each studied outcome. Results: After analyzing data from 1,445,441 patients who had been hospitalized due to COVID-19 in Iran, the rates of overall reinfection, reinfection occurring at least 90 days after the initial infection, recurrence, and hospital readmission among hospitalized patients were 67.79, 26.8, 41.61, and 30.53 per 1000 person-years, respectively. Among all cases of hospitalized reinfection (48292 cases), 38.61% occurred more than 90 days from the initial SARS-Cov-2 infection. Getting infected with COVID-19 in the fifth wave of the disease compared to getting infected in the first wave (P<0.001), having cancer (P<0.001), chronic kidney disease (P<0.001), and age over 80 years (P<0.001) were respectively the most important risk factors for overall reinfection. In contrast, age 19-44 years (P<0.001), intubation (P<0.001), fever (P<0.001), and cough (P<0.001) in the initial admission were the most important protective factors of overall reinfection, respectively. Conclusion: Reinfection and recurrence of COVID-19 after recovery and the rate of hospital readmission after discharge were remarkable. Advanced or young age, as well as having underlying conditions like cancer and chronic kidney disease, increase the risk of infection and readmission.

The presence of a sinus tract is associated with reinfection after two-stage revision surgery for prosthetic hip joint infection: a case-control study.

BACKGROUND: Reinfection rates after two-stage revision (TSR) for prosthetic joint infection (PJI) range from 7.9 to 14%. Many factors, including sinus tracts, are associated with reinfection after this procedure. This study aimed to delineate whether the presence of sinus tract could increase reinfection rate after TSR and to investigate other potential risk factors for reinfection after TSR. METHODS: We conducted a case-control study by retrospectively reviewing patients who underwent TSR for prosthetic hip joint infection from 2002 to 2022. The case group included patients who developed reinfection after TSR, while the control group consisted of patients who did not experience reinfection. PJI and reinfection after TSR were defined based on Delphi-based international consensus criteria. Patient demographics, past medical history, clinical manifestations, laboratory results, interval between stages, microbiological culture results were collected. Univariate analyses were utilized to assess the effect of sinus tract on reinfection and to identify other risk factors for reinfection after TSR. RESULTS: Six patients with reinfection after TSR were included as the case group and 32 patients without reinfection were in the control group. Significant difference was observed in percentage of patients with sinus tracts between the two groups (67% in the case group versus 19% in the control group, p = 0.031, OR = 8.7). Significant difference was also found in percentage of patients with positive cultures of synovial fluid and synovium harvested during the first-stage revision between the two groups (100% in the case group versus 50% in the control group, p = 0.030). Additionally, patients in the case group had a significantly higher C-reactive protein (CRP) level prior to the second stage revision than that of patients in the control group (8.80 mg/L versus 2.36 mg/L, p = 0.005), despite normal CRP levels in all patients. CONCLUSIONS: Our study revealed that the presence of sinus tracts could significantly increase risk of postoperative reinfection after TSR. Positive cultures during the first stage revision and elevated CRP level prior to the second stage revision could also increase the risk of reinfection after TSR. Further studies with a larger sample size are required. TRIAL REGISTRATION: Retrospectively registered.

Individual Heterogeneity and Trends in Hepatitis C Infection Risk Among People Who Inject Drugs: A Longitudinal Analysis.

Hepatitis C virus (HCV) causes substantial morbidity and mortality, particularly among people who inject drugs (PWID). While elimination of HCV as a public health problem may be possible through treatment-as-prevention, reinfection can attenuate the impact of treatment scale-up. There is a need to better understand the distribution and temporal trends in HCV infection risk, including among HCV-seropositive individuals who will be eligible for treatment and at risk for subsequent reinfection. In this analysis of 840 seronegative and seropositive PWID in Baltimore, MD USA, we used random forest methods to develop a composite risk score of HCV infection from sociodemographic and behavioural risk factors. We characterised the individual heterogeneity and temporal trajectories in this composite risk score using latent class methods and compared that index with a simpler, conventional measure, injection drug use frequency. We found that 15% of the population remained at high risk of HCV infection and reinfection by the composite metric for at least 10 years from study enrolment, while others experienced transient periods of moderate and low risk. Membership in this high-risk group was strongly associated with higher rates of HCV seroconversion and post-treatment viraemia, as a proxy of reinfection risk. Injection frequency alone was a poor measure of risk, evidenced by the weak associations between injection frequency classes and HCV-associated outcomes. Together, our results indicate HCV infection risk is not equally distributed among PWID nor well captured by injection frequency alone. HCV elimination programmes should consider targeted, multifaceted interventions among high-risk individuals to reduce reinfection.

CD4+ T cells re-wire granuloma cellularity and regulatory networks to promote immunomodulation following Mtb reinfection.

Immunological priming-in the context of either prior infection or vaccination-elicits protective responses against subsequent Mycobacterium tuberculosis (Mtb) infection. However, the changes that occur in the lung cellular milieu post-primary Mtb infection and their contributions to protection upon reinfection remain poorly understood. Using clinical and microbiological endpoints in a non-human primate reinfection model, we demonstrated that prior Mtb infection elicited a long-lasting protective response against subsequent Mtb exposure and was CD4+ T cell dependent. By analyzing data from primary infection, reinfection, and reinfection-CD4+ T cell-depleted granulomas, we found that the presence of CD4+ T cells during reinfection resulted in a less inflammatory lung milieu characterized by reprogrammed CD8+ T cells, reduced neutrophilia, and blunted type 1 immune signaling among myeloid cells. These results open avenues for developing vaccines and therapeutics that not only target lymphocytes but also modulate innate immune cells to limit tuberculosis (TB) disease.

SARS-CoV-2 reinfection broadens the antibody responses and promotes the phenotypic differentiation of virus-specific memory T cells in adolescents.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron subvariants raises concerns regarding the effectiveness of immunity acquired from previous Omicron subvariants breakthrough infections (BTIs) or reinfections (RIs) against the current circulating Omicron subvariants. In this study, we prospectively investigate the dynamic changes of virus-specific antibody and T cell responses among 77 adolescents following Omicron BA.2.3 BTI with or without subsequent Omicron BA.5 RI. Notably, the neutralizing antibodies (NAbs) titers against various detected SARS-CoV-2 variants, especially the emerging Omicron CH.1.1, XBB.1.5, XBB.1.16, EG.5.1, and JN.1 subvariants, exhibited a significant decrease along the time. A lower level of IgG and NAbs titers post-BTI was found to be closely associated with subsequent RI. Elevated NAbs levels and shortened antigenic distances were observed following Omicron BA.5 RI. Robust T cell responses against both Omicron BA.2- and CH.1.1-spike peptides were observed at each point visited. The exposure to Omicron BA.5 promoted phenotypic differentiation of virus-specific memory T cells, even among the non-seroconversion adolescents. Therefore, updated vaccines are needed to provide effective protection against newly emerging SARS-CoV-2 variants among adolescents.

Risk of COVID-19 Reinfection and Vaccine Breakthrough Infection, Madera County, California, 2021.

COVID-19 vaccine efficacy has been evaluated in controlled clinical trials and serves as a benchmark for evaluating the protection acquired from prior COVID-19 infection ("natural immunity"). A cohort of persons with a prior COVID-19 infection was matched to a cohort of COVID-19 vaccinated persons and the risk of reinfection post-COVID-19 infection was compared to the risk of a COVID-19 infection post-vaccination. The hazard ratio (HR) for risk of reinfection from day 90 to 300 after initial COVID-19 infection vs. vaccine breakthrough infection was 0.48, 95% Confidence Interval (CI) 0.31-0.73). Thus from 90 to 300 days after COVID-19 infection, the post-COVID-19 infection cohort had a lower risk of COVID-19 infection compared with those fully vaccinated. The risk of death associated with the initial COVID-19 infection requisite for acquiring post-COVID-19 immunity was also assessed. The hazard ratio (HR) for deaths from all causes among those acquiring immunity via COVID-19 infection vs. vaccination was 14.9 (95% CI 7.27-30.4). Thus, while post-COVID-19 immunity was on a level comparable to that of vaccination, there was a 15-fold higher mortality resulting from achieving "natural immunity" versus acquiring vaccine-provided immunity.

Re- Infection Rate of Opisthorchis Viverrini Five Years After Treatment with Praziquantel in High-Risk Area: A Community-Based Study.

BACKGROUND: Opisthorchis viverrini (OV)  is a significant public health problem in Thailand, and  OV reinfection poses a serious risk of cholangiocarcinoma with little evidence of a decrease.  While numerous studies have explored OV reinfection and prevalence, most have been limited to short study period. Therefore, there is a need for long-term investigations to gather sufficient evidence. OBJECTIVES: This study aimed to access the current status of re-infection rates in high- risk areas and to determine associations between factors of and re-infection of OV at 5 years after treatment  with praziquantel. MATERIALS AND METHODS: In total, this study included 457 participants from a cohort study. Each participant was required to answer a questionnaire and undergo stool examination using the formalin ethyl acetate concentration technique. Data were analyzed using descriptive statistics and multiple logistic regression. RESULT: Out of the total 457 participants, 418 (91.5%) successfully completed the questionnaires and underwent stool examinations. Among the participants, 10.8% showed re-infection with OV. Using multivariate analysis, factors significantly associated with reinfection OV included yearly income (OR adj = 2.14, 95%CI = 1.11- 4.12, p-value = 0.022) and past stool examination five years (OR adj = 2.47, 95%CI = 1.13-5.43, p-value = 0.023), respectively. CONCLUSIONS: Subjects who frequently experience OV reinfection should undergo CCA screening by experts while closely monitoring their raw fish consumption behavior. Moreover, it is essential to implement comprehensive programs aimed at promoting behavioral changes and provide preventive education, with a specific focus on high epidemic areas, to discourage the consumption of raw fish.

Impact of weekly iron-folic acid supplementation on nutritional status and parasitic reinfection among school-age children and adolescents in Sub-Saharan Africa: a systematic review and meta-analysis.

Background: Two significant etiological factors contributing to iron deficiency anemia, and undernutrition posing substantial public health challenges in Sub-Saharan Africa, are soil-transmitted helminths and malaria. This study carried out the effect of weekly iron-folic acid supplementation (WIFAS) on the nutrition and general health of school-age children and adolescents in Sub-Saharan Africa, a systematic review and meta-analysis have been conducted. Methods: To find pertinent publications for this study, a thorough search was carried out on May 20, 2023, across five databases: Pubmed (MEDLINE), Web of Science, Scopus, Cochrane Library, and Google Scholar. In addition, a search was conducted on August 23, 2023, to capture any new records. The inclusion criteria for the studies were based on school-age children and adolescent populations, randomized controlled trials, and investigations into the effects of WIFAS. The outcomes of interest were measured through anthropometric changes, malaria, and helminthic reinfection. Results: A systematic review of 11 articles revealed that WIFAS significantly decreased the risk of schistosomiasis reinfection by 21% among adolescents (risk ratio = 0.79, 95%CI: 0.66, 0.97; heterogeneity I 2 = 0.00%, P = 0.02). However, no significant impact was observed on the risk of malaria reinfection (risk ratio = 1.02, 95%CI: 0.92, 1.13; heterogeneity I 2 = 0.00%, P = 0.67) or A. Lumbricoides reinfection (risk ratio = 0.95, 95%CI: 0.75, 1.19; heterogeneity I 2 = 0.00%, P = 0.65). Moreover, the analysis demonstrated that there is no significant effect of iron-folic acid supplementation in measured height and height for age Z-score (HAZ) of the school-age children (Hedge's g -0.05, 95%CI: -0.3, 0.2; test for heterogeneity I 2 = 0.00%, P = 0.7) and (Hedge's g 0.12, 95%CI: -0.13, 0.37; test for heterogeneity I 2 = 0.00%, P = 0.36) respectively. Conclusion: The effectiveness of WIFAS in reducing the risk of schistosomiasis reinfection in adolescents has been demonstrated to be greater than that of a placebo or no intervention. Additionally, the narrative synthesis of iron-folic acid supplementation has emerged as a potential public health intervention for promoting weight change. However, there was no significant association between WIFAS and Ascariasis, trichuriasis, and hookworm. Moreover, the certainty of the evidence for the effects of WIFAS on height and malaria is low and therefore inconclusive. Whereas, the certainty of the evidence for the effectiveness of WIFAS on Schistosomiasis is moderate. Even though the mechanisms need further research WIFAS may be implemented as part of a comprehensive public health strategy to address schistosomiasis in adolescents. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023397898, PROSPERO (CRD42023397898).

A follow-up study on respiratory outcomes, quality of life and performance perception of SARS-CoV-2 primary and reinfection in elite athletes: A 9-month prospective study.

The prolonged consequences of SARS-CoV-2 on young elite athletes recovering from primary and reinfection are unclear. This study aimed to assess inspiratory/expiratory muscle strength and respiratory function at the time of spontaneous recovery at 3, 6, and 9 months after SARS-CoV-2 primary and reinfection in elite athletes. The study enrolled 25 elite male judoists, including 11 primary infection cases, five reinfection cases, and nine controls from the Türkiye Olympic Preparation Center. Inspiratory/expiratory muscle strength and respiratory function were measured, including maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC, and peak expiratory flow (PEF) before and up to 9 months after SARS-CoV-2 infection in the early pre-competition preparation phases. The most common symptoms reported by reinfection cases were fatigue (80%), dyspnea (60%), and muscle/joint pain (60%), while primary infection cases reported fatigue (73%), muscle/joint pain (45%), and headache (45%). MIP decreased by -14% and MEP decreased by -13% following the SARS-CoV-2 infection in reinfection cases. Likewise, FEV1 and FVC decreased by -5% and -8%, respectively; consequently, FEV1/FVC increased by 3%. Inspiratory/expiratory muscle strength and respiratory function improved rapidly after 9 months of SARS-CoV-2 infection in primary cases, whereas dysfunction persisted in reinfection cases. PEF was unaffected throughout the 9-month follow-up period. Reinfection may lead to further alterations in respiratory system relative to the primary infection, with a suspected restrictive pattern that remains dysfunctional in the third month; however, it improves significantly during a 9-month follow-up period.

Coordinated expansion of memory T follicular helper and B cells mediates spontaneous clearance of HCV reinfection.

Introduction: Follicular helper T cells are essential for helping in the maturation of B cells and the production of neutralizing antibodies (NAbs) during primary viral infections. However, their role during recall responses is unclear. Here, we used hepatitis C virus (HCV) reinfection in humans as a model to study the recall collaborative interaction between circulating CD4 T follicular helper cells (cTfh) and memory B cells (MBCs) leading to the generation of NAbs. Methods: We evaluated this interaction longitudinally in subjects who have spontaneously resolved primary HCV infection during a subsequent reinfection episode that resulted in either another spontaneous resolution (SR/SR, n = 14) or chronic infection (SR/CI, n = 8). Results: Both groups exhibited virus-specific memory T cells that expanded upon reinfection. However, early expansion of activated cTfh (CD4+CXCR5+PD-1+ICOS+FoxP3-) occurred in SR/SR only. The frequency of activated cTfh negatively correlated with time post-infection. Concomitantly, NAbs and HCV-specific MBCs (CD19+CD27+IgM-E2-Tet+) peaked during the early acute phase in SR/SR but not in SR/CI. Finally, the frequency of the activated cTfh1 (CXCR3+CCR6-) subset correlated with the neutralization breadth and potency of NAbs. Conclusion: These results underscore a key role for early activation of cTfh1 cells in helping antigen-specific B cells to produce NAbs that mediate the clearance of HCV reinfection.

Pregnancy outcomes in women with severe acute respiratory syndrome coronavirus 2 reinfections compared to those with a single infection: a retrospective cohort study.

BACKGROUND: To assess pregnancy outcomes in women with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection. METHODS: This was a retrospective cohort study that included pregnant women who contracted coronavirus disease 2019 (COVID-19) once or twice during pregnancy and who gave birth between 1 October 2022 and 15 August 2023 in Shanghai First Maternity and Infant Hospital (Shanghai, China). We collected their clinical data and compared the frequency of adverse pregnancy outcomes between the reinfection group and the primary infection group, such as preterm birth, fetal growth restriction (FGR), hypertensive disorders of pregnancy (HDP), common pregnancy-related conditions, birth weight, and neonatal unit admission. RESULTS: We observed a 7.7% reinfection rate among the 1,405 women who contracted COVID-19 during pregnancy. There were no significant differences in the frequency of preterm birth, FGR, HDP, other common pregnancy-related conditions, birth weight, or rate of neonatal unit admission between the reinfection and single infection groups. All our participants were unvaccinated, and all had mild symptoms. CONCLUSION: Our study showed no significant association between SARS-CoV-2 reinfection and adverse pregnancy outcomes.