Risk Of Reinfection Research Articles

Effect of wild-type vaccine doses on BA.5 hybrid immunity, disease severity, and XBB reinfection risk.

Vaccination against the wild-type (WT) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus did not produce detectable levels of neutralizing antibodies (NAbs) against the BA.5 strain before it emerged. However, coronavirus disease-2019 (COVID-19) severity varied highly between unvaccinated, partially vaccinated, and fully vaccinated individuals, for unknown reasons. We assessed the severity of BA.5 infection and the risk of XBB strain reinfection and measured serum levels of NAbs against WT, BA.5, and XBB.1.9.1 SARS-CoV-2 strains at varying time points in 1,373 individuals who received zero, one, two, or three WT vaccine doses. We found that two to three WT doses significantly increased WT and BA.5 NAb levels and reduced the incidence of COVID-19-associated pneumonia upon BA.5 strain infection compared to zero to one dose. Regarding XBB reinfection, those who received two to three doses and were infected with the BA.5 variant exhibited a significantly lower reinfection risk compared to those who received zero to one dose. RNA analysis revealed that the differentially expressed genes between the two to three dose and unvaccinated groups were enriched in B cell activation, cytokine-cytokine receptor interaction, complement, and monocyte activation functions-indicating that vaccination increased the antibody response and reduced inflammation. Our results suggest that multiple antigen exposures to either matched or unmatched SARS-COV-2 variants, through vaccination or infection, may be necessary to achieve significant immune imprinting.IMPORTANCEThe administration of coronavirus disease-2019 (COVID-19) vaccines that do not perfectly match the viral strains that individuals become infected with has been found to impact the resultant illness severity-although the precise mechanism underlying this phenomenon remains unclear. We assessed viral clearance, as well as serum levels of inflammatory cytokines and neutralizing antibodies (NAbs) against wild-type, BA.5, and XBB.1.9.1 variants of the severe acute respiratory syndrome coronavirus 2 among individuals who received varying doses of such strain-mismatched vaccines. Notably, vaccination with ≥2 doses of strain-mismatched COVID-19 vaccines appeared to stimulate the production of specific NAbs during infection with new variants, as well as attenuate the inflammatory response and enhance viral clearance. Such vaccination regimens can also reduce the risk of reinfection. These findings may be important for guiding the development of future COVID-19 vaccination strategies that target both matched and mismatched viral variants.

The use of p-toluenesulfonic acid in the removal of biofilm in chronic ulcers

Background: Bacterial biofilms represent a topic of great concern due to their ability to cause chronic, sometimes fatal infections. Considering the prevalence and pathogenicity of biofilms in chronic ulcers, an observational study was designed to evaluate the anti-biofilm capabilities of p-toluenesulfonic acid, using it in the chronic ulcers of patients belonging to the Diabetic Foot clinic. Methods: Preliminary analysis of an observational study on patients attending the diabetic foot clinic with leg ulcers for at least 4 weeks. 17 patients treated with p-toluenesulfonic acid on a weekly basis for a maximum of 16 weeks. The primary outcome was 100% granulation tissue formation at week 16 and 50% reduction in initial chronic ulcer size. Results: The average treatment time was 10 ± 4.8 weeks. 8 patients healed, 7 are undergoing treatment, 1 required reoperation due to post-operative complications and 1 spontaneously dropped out of the study after 6 weeks. In the sample of healed patients, the average treatment time was 10.5 weeks with 100% granulation present at the 6th week. The reduction in the overall size of the ulcer and of the granulation area is not significant in the total sample. The data improves in the sample of healed patients even if it does not reach significance (lesion p-value 0.094, granulation p-value 0.13). Applying the analysis to the delta of the two variables, a measurement of the area that coincides with the margins of the ulcer, a p-value of 0.069 is obtained. The behaviour of the sample does not change when stratified by the dressings applied after treatment with p-toluenesulfonic acid. Conclusions: Treatment with p-toluenesulfonic acid promotes tissue granulation regardless of the type of dressing subsequently applied. The data on the evolution of the size of the lesions were not significant due to the smallness of the sample but in the sample of healed persons, the formation of granulation after an average of 6 applications transforms the "chronic" ulcer into an "active" ulcer, promoting closure within the subsequent 4 weeks. The appearance of granulation confirms healing. Elimination of biofilm with p-toluenesulfonic acid can reduce healing times and the risk of reinfection.

Epidemiological Characteristics and Spatiotemporal Clustering of Symptomatic Hepatitis E Virus Reinfection in Zhejiang Province, 2005–2023

Hepatitis E virus (HEV) reinfection is prevalent among the population, posing a significant burden on prevention and control efforts. In this study, we conducted a comprehensive analysis of data from China’s Disease Prevention and Control Information System’s infectious disease surveillance system to identify the epidemiological characteristics, spatiotemporal clustering, and high-risk populations of HEV reinfection. From 2005 to 2023, HEV reinfection in Zhejiang Province exhibited a fluctuating trend, peaking in 2020, with a 3–5-year lag compared to the pattern of HEV incidence. The Cox model indicated that individuals aged 40–50 and females are at higher risk of reinfection. Spatial autocorrelation was observed in reinfection cases from 2011 to 2016, with high–high clustering areas concentrated in downtown Hangzhou. Additionally, spatiotemporal scanning revealed that the clustering of reinfection cases has shifted from Hangzhou to coastal areas in recent years. Our findings suggest that targeted prevention and control measures for HEV rein fection should be implemented based on the characteristics of high-risk populations and spatiotemporal clustering patterns.

Hepatitis C treatment and behavioural risk among men who have sex with men with HIV: comparing interferon and direct-acting antiviral eras.

Little is known about the effect of HCV treatment on sexual risk behaviour among men who have sex with men (MSM) with HIV by treatment type (IFN-based vs DAA-based). MSM with HIV and recently acquired HCV infection enrolled in the observational MOSAIC cohort. Using data from 2009-2018, we evaluated risk behaviour through a validated HCV risk score (where ≥2 indicated high risk) and its individual risk behaviours. Levels of risk behaviour before, during and after treatment were modelled for each treatment episode using linear and logistic regression with Generalized Estimating Equations adjusting for DAA availability and number of re-infections. 140 MSM with a median age of 45 years (interquartile range=40-49) yielded 180 treatment episodes (n=131 IFN-based, n=49 DAA-based). Adjusted mean risk score before, during and after treatment was 2.4 (95% confidence interval (CI)=2.1-2.6), 0.9 (95%CI=0.8-1.0) and 1.7 (95%CI=1.5-1.8), respectively. Before treatment, no differences in mean HCV risk score or proportion of specific behaviours were found between the regimen groups. During treatment, MSM treated with DAAs had a higher average risk score and proportion of receptive condomless anal sex, sharing toys and unprotected fisting than those treated with IFN. After treatment, the proportion sharing straws were significantly higher in MSM treated with DAAs than IFN. MSM treated with DAAs, compared to IFN, had higher levels of HCV-related risk behaviour during treatment. The higher risk of HCV re-infection in the DAA-era underscores the need for ongoing HCV testing and behavioural interventions against HCV.

PH-Responsive MOF Nanoparticles Equipped with Hydrophilic "Armor" Assist Fungicides in Controlling Peanut Southern Blight.

The development of novel, safe, and efficient pest and disease control technologies for agricultural crops remains a pivotal area of research. In this study, by combining ZIF-8 and ZIF-90, a water-stable, pH-responsive bilayer MOF nanoparticle (NP) named Z8@Z90 was created, and tebuconazole (TEB) was added to form T@Z8@Z90, used for controlling peanut southern blight. The loading efficiency of TEB within the T@Z8@Z90 reached 26.15%, enabling rapid release in acidic environments triggered by oxalic acid (OA) secreted by Sclerotium rolfsii. In vitro experiments showed that T@Z8@Z90 can regulate the oxalic acid secretion of S. rolfsii and destroy its cell membrane structure. Additional experiments revealed that T@Z8@Z90 reduced sclerotial formation, decreased the total protein content of sclerotia, and influenced their sensitivity to pesticides, thereby mitigating the risk of reinfection by S. rolfsii. Notably, T@Z8@Z90 exhibited efficient translocation within peanut seedlings, being absorbed through the roots and transported to the leaves. At a concentration of 200 mg/L, T@Z8@Z90 exhibited high safety profiles for peanut seedling growth compared to the TEB suspension. Moreover, T@Z8@Z90 is safer for earthworms than TEB SC. Overall, this study offers valuable insights for the management of soil-borne diseases in agriculture and contributes to the advancement of sustainable agricultural practices.

Intramedullary nailing of coated and uncoated nails in infected tibial pseudarthrosis : Results of aretrospective examination of 56patients

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. 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. A retrospective analysis of patients with an infected pseudarthrosis of the tibia in whom agentamycin-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. 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 abony consolidation at the time of the exacerbation in 10patients (50%). At the end of the follow-up aconsolidation was present in 48patients (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. Despite arelatively high arate 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.

Evaluation of Antibody Response and Reinfection in Improved Hypertensive, Cardiac, and Diabetic Patients with COVID-19 for Six Months in Unvaccinated Outpatients

Background: This study presents a unique investigation into the relationship between the persistence of IgG antibody levels and reinfection in recovered coronavirus disease 2019 (COVID-19) patients. By shedding light on this aspect, we aim to address concerns about the risk of reinfection in unvaccinated patients, offering a fresh perspective in the current COVID-19 research landscape. Objectives: This study takes a novel approach by focusing on the antibody response and reinfection in COVID-19 patients who were treated in outpatient settings for six months. This approach distinguishes our research within the broader context of COVID-19 studies. Methods: Our comprehensive and rigorous prospective cohort study included 149 COVID-19 outpatients referred to Imam Ali Clinic in Dezfoul City, Khuzestan province, Iran. Data was meticulously collected from September 2021 to February 2022. All unvaccinated patients underwent RT-PCR testing, and their anti-SARS-CoV-2 IgM/IgG levels were measured at the onset of illness. Serum IgG levels were then measured again after three and six months using ELISA. Results: All COVID-19 patients had their IgG antibody levels tested three times (on days two to four of the illness, at three months, and at six months). Significant differences in IgG antibody levels were observed between the vaccinated and unvaccinated groups during each period (P < 0.05). Additionally, there were substantial differences between the hypertension and non-hypertension groups (P = 0.032). Importantly, our findings reaffirm the impartiality of our research, as no significant differences were found between reinfection rates and various demographic or disease-related factors. Conclusions: The findings of this study suggest that high levels of IgG antibodies in unvaccinated patients could potentially reduce the risk of reinfection. This insight could have important implications for public health strategies and the management of COVID-19 in unvaccinated populations, providing valuable information for decision-makers in the field.

Understanding the Omicron Variant Impact in Healthcare Workers: Insights from the Prospective COVID-19 Post-Immunization Serological Cohort in Munich (KoCo-Impf) on Risk Factors for Breakthrough and Reinfections.

This study analyzes immune responses to SARS-CoV-2 vaccination and infection, including asymptomatic cases, focusing on infection risks during the Omicron wave, particularly among high-risk healthcare workers. In the KoCo-Impf study, we monitored 6088 vaccinated participants in Munich aged 18 and above. From 13 May to 31 July 2022, 2351 participants were follow-uped. Logistic regression models evaluated primary, secondary, and breakthrough infections (BTIs). Roche Elecsys® Anti-SARS-CoV-2 assays detected prior infections (via anti-Nucleocapsid antibodies) and assessed vaccination/infection impact (via anti-Spike antibodies) using dried blood spots. Our findings revealed an anti-Nucleocapsid seroprevalence of 44.1%. BTIs occurred in 38.8% of participants, with reinfections in 48.0%. Follow-up participation was inversely associated with current smoking and non-vaccination, while significantly increasing with age and receipt of three vaccine doses. Larger household sizes and younger age increased infection risks, whereas multiple vaccinations and older age reduced them. Household size and specific institutional subgroups were risk factors for BTIs. The anti-Nucleocapsid value prior to the second infection was significantly associated with reinfection risk. Institutional subgroups influenced all models, underscoring the importance of tailored outbreak responses. The KoCo-Impf study underscores the importance of vaccination, demographic factors, and institutional settings in understanding SARS-CoV-2 infection risks during the Omicron wave.

Analysis of re-infection cases and influencing factors post first severe COVID-19 wave in Jiangsu Province, China.

This study aimed to assess COVID-19 re-infection rates among individuals previously infected between 2020 and November 2022, particularly during the first wave of high-intensity transmission, and to identify the risk factors associated with re-infection in Jiangsu Province, China. Epidemiological investigations were conducted through telephone interviews and face-to-face visits in February and March 2023. Statistical analyses included the Chi-square or Fisher`s exact test for categorical data, Student's t-test for numerical data, Poisson regression for influencing factors, and Kaplan-Meier for cumulative re-infection risk. Among 12,910 individuals surveyed, 957 (7.4%) cases of re-infection were identified. Re-infection rates varied significantly by initial infection period: 42.5% in January-February 2020, 15.5% in July-August 2021, 6.7% in March-April 2022, and 1.1% in September-October 2022. Females and individuals aged 18-50 years were more susceptible to re-infection. A reduced risk of re-infection was observed in those who received four vaccine doses, with a relative risk of 0.25 (p = 0.019). For populations prone to COVID-19 re-infections, particularly females and young adults aged 18-50 years, receiving four or more vaccine doses effectively reduces the likelihood of repeated infections. These findings emphasize the need to prioritize vaccination and protect high-risk groups in COVID-19 prevention efforts.

Risk of Reinfection and Incidence of Chronic Symptoms After SARS-CoV-2 Infections.

This study showed that a severe acute respiratory syndrome coronavirus 2 infection reduced the risk of reinfection among vaccinated individuals by 0.50 (95% CI, 0.39-0.64) over a 1-year period, after accounting for unreported infections using avidity-based serology. Reciprocally, chronic symptoms increased from a baseline of 21% (95% CI, 16%-28%) among infection-naïve individuals to 43% (95% CI, 30%-61%) in reinfected individuals.

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.

Characteristics and predictors of Long Covid in children: a 3-year prospective cohort study

Children can develop Long Covid, however long term outcomes and their predictors are poorly described in these patients. The primary aim is to describe characteristics and predictors of Long Covid in children assessed in-clinics up to 36 months post-SARS-CoV-2 infection, as well as investigate the role of vaccines in preventing Long Covid, risk of reinfections and development of autoimmune diseases. Children aged 0-18 years old with confirmed SARS-CoV-2 infection were invited for a prospective follow-up assessment at a peadiatric post-covid clinic in Rome, Italy, at serial intervals (3-, 6-, 12-, 18-, 24- and 36-months post-infection onset, between 01/02/2020 and 28/02/2024). Long Covid was defined as persistence of otherwise unexplained symptoms for at least three months after initial infection. 1319 patients were initially included, 1296 reached the 3 months follow-up or more. Of the patients who underwent multiple follow-ups, 23.2% (301), 169 (13.2%), 89 (7.9%), 67 (6.1%), 47 (7.1%) were diagnosed with Long Covid at 3-6-12-18-24 months, respectively For the primary outcome of Long Covid at three months, age >12 years (P<0.001, OR 11.33, 95% CI 4.2; 15.15), comorbidities (P=0.008, OR 1.83, 95% CI 1.06; 2.44), being infected with original variants (P<0.001, OR 4.77, 95% CI 2.46; 14.47), female sex (P<0.001, OR 1.62, 95% CI 1.02; 1.89) were statistically significant risk factors. Age >12 years (P=0.002, OR 9.37, 95% CI 1.58; 8.64), and infection with original (P=0.012, OR 3.52, 95% CI 1.32; 8.64) and alfa (P<0.001, OR 4.09, 95% CI 2.01; 8.3) SARS-CoV-2 variants remained statistically significant risk factors for Long Covid duration for at least 18 months. Vaccination was associated with a lower risk of long covid at 3, 6 and 12 months for older children and a lower risk of reinfections. Being infected with the original SARS-CoV-2 variant was associated with a higher risk of new-onset autoimmune diseases ((P=0.035, 95% CI 1.12; 2.4). One patient was diagnosed with Long Covid after a re-infection. This is the longest follow-up study of children with SARS-CoV-2 infection, showing a significant and long-lasting burden of Long Covid in the pediatric population. Our findings highlight the urgent need of investing in pediatric Long Covid in order to find effective diagnostic and therapeutic approaches, as well can inform preventive strategies in case of future pandemics. This study has been funde by Pfizer non-competitive grant, granted to DB (#65925795).

Prognostic Implications of Unexpected Positive Intraoperative Cultures in Two-Stage Knee Arthroplasty Reimplantations: A Minimum Five-Year Retrospective Analysis

BackgroundThe clinical challenge of unexpected positive intraoperative cultures (UPICs) persists in 2-stage resection arthroplasty for managing periprosthetic joint infections (PJIs) following total knee arthroplasty.(TKA). This study aimed to investigate the incidence of UPICs during the definitive reimplantation phase of 2-stage resection arthroplasty of the knee and to assess both the infection-free and revision-free survivorship of the implanted prosthesis. MethodsThis retrospective study included 450 2-stage resection arthroplasties of primary knee prostheses performed between January 2012 and April 2017. Patients were excluded if they: (1) underwent three or more staged resections, (2) had ambiguous clinical documentation or deviated from the 2-stage protocol, or (3) underwent revision arthroplasty prior to the PJI. Additionally, patients presumed aseptic before the second-stage reimplantation were excluded if they lacked joint aspiration or met the 2011 Musculoskeletal Infection Society criteria for PJI before implantation. ResultsAfter exclusions, 300 patients were analyzed. Among them, 14% had UPIC during the second-stage reimplantation. The follow-up time was 2,316 (range, 1,888 to 3,737) days and 2,531 (range, 1,947 to 3,349) days for UPIC and negative intraoperative culture (NIC) groups, respectively. Rerevision due to subsequent PJI occurred in 26.2% of UPIC patients and 15.1% of NIC patients. The 2-year infection-free survival rates for the NIC, one UPIC, and ≥ two UPIC cohorts were 99.5, 98.2, and 94.3%, respectively, while the 5-year survival rates were 92.1, 91.1, and 54.3%, respectively. The unfavorable survivorship was significantly different in multiple UPIC cases (P < 0.001). Multiple UPICs with pathogens consistent with the first-stage findings were strongly associated with the risk of reinfection (P < 0.001). ConclusionsAn UPIC was identified in 14% of second-stage reimplantations. Patients who had multiple UPICs demonstrated truncated survivorship and suboptimal outcomes relative to the NIC and single UPIC cohorts, especially with pathogen consistency to the first-stage surgery. Level of evidenceIII.

A New-fangled COVID-19 Variant, Eris, Might be the One to Lookout in 2023 or far from Over.

Coronavirus Disease-19 (COVID-19) is an infectious disease brought on by the extremely pathogenic and contagious severe acute respiratory syndrome-virus-2 (SARS-CoV-2). The agenda for the COVID-19 pandemic is dynamic and includes recent developments. Seven variants under monitoring (VUMs), one variant of interest (VOI), XBB.1.5, and their offspring lineages are currently being actively monitored by WHO. The VUMs are BA.2.75, CH.1.1, BQ.1, XBB (with the exception of XBB.1.5, XBB.1.16, and XBB.1.9.1), XBF, and XBB.1.16. With 95 countries having reported finding XBB.1.5 (VOI), it is still the most common strain worldwide, responsible for 47.9% of cases from epidemiological January to March 2023. Seventy nations discovered XBB.1.5 in February and March 2023 and posted sequencing data to GISAID. Of the 43 nations that uploaded more than 50 sequences, XBB.1.5 prevalence has increased to more than 50% in 11 nations. Over 23000 deaths and 3 million new cases were recorded globally in March and April 2023. Worldwide detection of a new COVID-19 strain has prompted specialists to issue a warning that the virus is "circulating unchecked". The Greek goddess of conflict and discord Eris has inspired the nicknaming of EG 5.1, a subvariant of Omicron. The strain is becoming more prevalent in the USA and cases are increasing in the UK. The severity of each SARS-CoV- 2 variant has been comparable, although a more severe form might develop. Eris is an ancestor of Omicron and exhibits some of its characteristics. Reinfection risk can be influenced by a variety of variables, including age, location, and health equity and the COVID-19 vaccine is more or less effective depending on the strain.

Post-Hoc Analysis of Potential Correlates of Protection of a Recombinant SARS-CoV-2 Spike Protein Extracellular Domain Vaccine Formulated with Advax-CpG55.2-Adjuvant.

SpikoGen® vaccine is a subunit COVID-19 vaccine composed of an insect cell expressed recombinant spike protein extracellular domain formulated with Advax-CpG55.2™ adjuvant. A randomized double-blind, placebo-controlled Phase II clinical trial was conducted in 400 adult subjects who were randomized 3:1 to receive two intramuscular doses three weeks apart of either SpikoGen® vaccine 25 μg or saline placebo, as previously reported. This study reports a post hoc analysis of the trial data to explore potential immune correlates of SpikoGen® vaccine protection. A range of humoral markers collected pre- and post-vaccination, including spike- and RBD-binding IgG and IgA, surrogate (sVNT), and conventional (cVNT) virus neutralization tests were compared between participants who remained infection-free or got infected over three months of follow-up. From 2 weeks after the second vaccine dose, 21 participants were diagnosed with SARS-CoV-2 infection, 13 (4.2%) in the SpikoGen® group and 8 (9%) in the placebo group. Those in the vaccinated group who experienced breakthrough infections had significantly lower sVNT titers (GMT 5.75 μg/mL, 95% CI; 3.72-8.91) two weeks after the second dose (day 35) than those who did not get infected (GMT 21.06 μg/mL, 95% CI; 16.57-26.76). Conversely, those who did not develop SARS-CoV-2 infection during follow-up had significantly higher baseline sVNT, cVNT, spike-binding IgG and IgA, and RBD-binding IgG, consistent with a past SARS-CoV-2 infection. SpikoGen® further reduced the risk of re-infection (OR 0.29) in baseline seropositive (previously infected) as well as baseline seronegative participants. This indicates that while SpikoGen vaccine is protective in seronegative individuals, those with hybrid immunity have the most robust protection.

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.

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. 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. 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%). 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.

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 300days 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.

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

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. 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. 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. 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. https://www.crd.york.ac.uk/PROSPERO/, identifier, CRD42024539682.

Hepatitis C Virus Reinfection Among People Who Inject Drugs

Hepatitis C virus (HCV) reinfection after curative treatment remains a concern for people who inject drugs. To assess the incidence of HCV reinfection and associated risk factors. This cohort study is a secondary analysis of a randomized clinical trial that was conducted across opioid treatment programs and community health centers in the US between September 2016 and August 2018. The current analyses were performed in March 2022. People who inject drugs who achieved sustained virologic response (SVR) were followed for up to 42 months. Patients were randomly assigned to receive modified directly observed therapy or patient navigation. The primary outcome was rate of HCV reinfection. Change in reinfection rates over time was assessed using a Poisson regression model. A total of 415 participants (mean [SD] age, 44.7 [11.5] years; 302 male [72.8%]) achieved a SVR and had 1 or more post-SVR assessments for HCV RNA. Overall, 302 (72.8%) reported recent injection drug use, 192 (46.3%) were living in unstable housing, and 313 (75.4%) had received recent methadone or buprenorphine for opioid use disorder. The overall reinfection rate was 11.4 per 100 person-years at risk (95% CI, 8.7-14.7 per 100 person-years at risk) over 518 person-years of follow-up. Reinfection rates varied significantly across sites, ranging from 2.9 per 100 person-years at risk (95% CI, 0.1-16.3 per 100 person-years) to 25.2 per 100 person-years at risk (95% CI, 15.6-38.5 per 100 person-years at risk) (P = .006). There was a significant decrease in incident reinfection with increasing post-SVR follow-up (weeks 0-24, 15.5 per 100 person-years; 95% CI, 10.3-22.3 per 100 person-years; weeks 73-144, 4.3 per 100 person-years; 95% CI, 0.9-12.5 per 100 person-years; P = .008). Reinfection rates were lower for participants aged 40 years or older than for younger participants (adjusted incidence rate ratio, 0.32; 95% CI, 0.18-0.57) and for participants for whom methamphetamine was not detected in urinary drug screening compared with participants for whom methamphetamine was detected (adjusted incidence rate ratio, 0.41; 95% CI, 0.21-0.82). Participants who reported injection drug use within the preceding 3 months had higher risk of reinfection than those who did not have recent injection drug use (adjusted incidence rate ratio, 3.33; 95% CI, 1.86-5.97). In this cohort study of people who injected drugs and were treated for HCV infection in community settings, reinfection was high in the period immediately after SVR but decreased significantly over time. These findings highlight the importance of early intervention to prevent reinfection. ClinicalTrials.gov Identifier: NCT02824640.

THE ROLE OF ANTIBACTERIAL HYDROGEL COATING ON COMPLICATION RISKS AFTER COMPLEX PRIMARY AND CEMENTLESS HIP REVISION ARTHROPLASTY: A RETROSPECTIVE MATCHED COHORT STUDY

This study aimed to verify the hypothesis that an antibiotic loaded hydrogel, defensive antimicrobial coating (DAC), reduces overall complication and infection rates when used for high-risk primary and revision total hip arthroplasty (THA).This was a retrospective study matched cohort study of 238 patients, treated with cementless implants with and without DAC. A sub-group analysis of patients undergoing 2nd stage revision THA for prosthetic joint infection (PJI) was also conducted. Re-infection rates within 2 years, complications necessitating surgical intervention and radiographic analysis for aseptic loosening was assessed.The mean age was 68.3±11.5 years, with 39 (32.8%) Macpherson class A, 64 (53.8%) class B and 16 (13.4%) class C patients. 4 (3.4%) patients in the DAC group developed complications including 1 PJI and 1 delayed wound healing, while 13 (10.9%) patients in the control group developed complications including 5 PJIs and 3 delayed wound healing (p=0.032). PJI rates (p=0.136) and delayed wound healing rates (p=0.337) were not statistically significant. For 2nd stage revision THA for PJI there were 86 patients in the DAC group and 45 in the control group. 1 (1.2%) patient in the DAC group developed complications with no recurrences of infection or delayed wound healing, while 10 (22.2%) patients in the control group developed complications including 4 recurrent PJI and 1 delayed wound healing (p=0.003). Recurrent PJI rates were statistically significant (p=0.005) while delayed wound healing rates were not (p=0.165). Patients treated with DAC also had lower rates of aseptic loosening (0% vs 6.7%; p=0.015).Antibiotic impregnated hydrogel coatings on cementless implants showed decreased complication rates after complex primary or revision THA. In 2nd stage revision THA for PJI, it was associated with reduced risk of re-infection and aseptic loosening.