Background: Respiratory Syncytial Virus (RSV) is a significant cause of morbidity and mortality among lung transplant (LTx) recipients. Therapeutic options are limited, emphasizing the importance of prevention. The Arexvy^® vaccine (RSVPreF3) showed promising efficacy among immunocompetent adults; however, data on its immunogenicity in solid organ transplant recipients remain unclear. Methods: A single-center retrospective cohort study, including all LTx recipients who were vaccinated with Arexvy in February 2024. Baseline and follow-up serum samples (1, 3, and 6 months post-vaccination) were analyzed for antibody responses using a commercial RSV ELISA kit and micro-neutralization assays against historical reference RSV A/B ATCC strains and seasonal RSV strains. Adverse events were documented. Results: A total of 28 recipients received the vaccine. Twenty-one (75%) were male, and the median age was 62 years (interquartile range [IQR], 53–67). The median time from transplant was 486 days (IQR, 243–966). Vaccination elicited strong immunogenic responses, demonstrating a twofold increase in ELISA-determined antibody levels at one month post-vaccination, which were sustained for six months. At one month, 67% of recipients had antibody levels exceeding the cutoff threshold. Micro-neutralization assays showed a significant increase in neutralizing antibodies against all tested variants (RSV A/B ATCC and seasonal RSV A/B), with titers remaining at least twofold higher than pre-vaccination levels. No serious adverse events were observed. Conclusions: Our findings demonstrate a sustained antibody response to the Arexvy^® vaccine in a cohort of LTx recipients, with antibody titers sustained over six months. Further research is needed to assess the long-term durability of the immune response and the potential immunogenicity of this vaccine in LTx populations.

Background: Human rhinovirus (HRV) is a major cause of respiratory illness, however data on clinical presentation, outcomes across age-groups and associations with HRV subtypes are limited. Methods: Clinical characteristics and outcomes of hospitalized HRV-positive patients with cycle threshold (Ct)≤32 were collected retrospectively and analyzed in relation to age-groups and subtypes. Results: Among 738 patients, the age distribution was: 0–1 (148,20.1%), 1–3 (94,12.7%), 3–5 (44,5.9%), 5–18 (76,10.3%), 18–40 (51,6.9%), 40–65 (95,12.9%) and ≥65 (230,31.2%). Younger children more frequently presented with bronchiolitis and asthma exacerbation, while older adults experienced higher rates of pneumonia and chronic obstructive pulmonary disease (COPD) exacerbation. ICU admissions and mechanical ventilation were more common in younger children, whereas oxygen support was predominant in older adults. Of 119 sequenced samples, HRV-A was the predominant species (69%), followed by HRV-C (28.5%), with both exhibiting considerable genetic subtype diversity. Lower respiratory tract infection (LRTI) associated with HRV-C was found only in adults while severe and critical outcomes with HRV-A and HRV-C occurred in both children and adults. When compared with human metapneumovirus (hMPV), a known pathogenic respiratory virus, no differences in severe outcomes were noted, however, HRV patients aged ≥65 had a higher proportion of critical outcomes. Conclusions: HRV infection is associated with significant morbidity across age-groups, with distinct clinical presentation and outcomes. ICU admissions were more frequent in children, while older adults required oxygen support. The genetic diversity and age-related differences in HRV subtypes underscore its clinical impact in both pediatric and adult populations.

Vaccination against COVID-19 and influenza provides the best defense against morbidity and mortality. Administering both vaccines concurrently may increase vaccination rates and reduce the burden on the healthcare system. This study evaluated the immunogenicity of healthcare workers in Israel who were co-administered with the Omicron BA.4/BA.5 bivalent COVID-19 vaccine and the 2022–2023 quadrivalent influenza vaccine. SARS-CoV-2 neutralizing antibody titers were measured via microneutralization while influenza antibody titers were measured via hemagglutination inhibition. No immunogenic interference was observed by either vaccine when co-administered. Antibody titers against SARS-CoV-2 variants increased significantly in the cohort receiving the COVID-19 vaccine alone and in combination with the influenza vaccine. Antibody titers against the A/H1N1 influenza strain increased significantly in the cohort receiving the influenza vaccine alone and in combination with the COVID-19 vaccine. Antibody titers against B/Victoria increased significantly in the cohort that received both vaccines. This study has important public health implications for the 2023–2024 winter season, and supports co-administration of both vaccines as a viable immunization strategy.

Respiratory syncytial virus (RSV) is a major cause of morbidity and mortality among older adults. Limited information is available in Israel regarding RSV outcomes, particularly compared to influenza, to guide strategies for RSV vaccination. This study aimed to characterize RSV infection and predictors of clinical outcomes among hospitalized adults aged ≥ 60 years in Israel between 2016 and 2023, and to compare disease severity and outcomes with those of seasonal influenza hospitalizations. A retrospective analysis was conducted of hospitalized adults aged ≥ 60 years with positive RSV or influenza confirmed via standard-of-care RT-PCR between 2016 and 2023. The primary outcome was a composite of intensive care unit (ICU) admission, mechanical ventilation, vasopressor support, or 30-day mortality. Cardiovascular complications were recorded. An inverse probability treatment weighting (IPTW) was used to adjust for potential confounding. Weighted and unweighted relative risks (RRs) were estimated to compare clinical outcomes between RSV and influenza. Overall, 817 RSV-positive and 2113 influenza-positive patients were included. Among patients with RSV, 30-day and 90-day mortality rates were 11.9% and 18.8% respectively; ICU admission was required for 10.6%, mechanical ventilation for 6.4%, and vasopressor support for 6.5%. Tachyarrhythmia was documented in 17.7% and ischemia in 9.9%. Predictors of the composite primary outcome included chronic pulmonary disease, lower respiratory tract infection, hypothermia, elevated pulse, lower blood pressure and increased creatinine. In IPTW-adjusted analyses, RSV infection had a trend for increased risk for the composite primary outcome (RR 1.03, 95% confidence interval [CI] 1.00, 1.06) and 90-day mortality (RR 1.02, 95% CI 0.99, 1.05) compared with influenza. Among hospitalized older adults, RSV infection carries considerable morbidity and mortality and may have a higher risk for poor clinical outcomes compared with influenza. These findings support the prioritization of RSV vaccination programs among older adults.

Objectives: The emergence of SARS-CoV-2 variants with enhanced immune evasion capabilities poses ongoing challenges for maintaining population-level immunity. This study aim to evaluate neutralizing antibody responses to the wild-type (WT) strain and the Omicron sublineage XBB.1.9 in the Israeli population using serum samples collected between August 2022 and January 2023, prior to widespread circulation of XBB.1.9. Methods: Pseudovirus-based microneutralization assays incorporating variant-specific spike proteins were employed to measure neutralizing geometric mean titers (GMTs) across subgroups categorized by age, gender, socioeconomic status, and geographic region. Results: Neutralizing titers against XBB.1.9 were significantly lower than those against WT across all demographic groups, with a 29-fold reduction in neutralization activity against XBB.1.9, underscoring the immune escape potential of XBB.1.9. For WT, older adults (≥65 years) exhibited higher titers than younger individuals (p < 0.01), whereas no significant age-related differences were observed for XBB.1.9 (p > 0.05). Regional disparities in WT immunity were identified, with higher titers in Northern Israel compared to Jerusalem and Southern regions. By contrast, XBB.1.9 neutralization showed no significant regional variation. Conclusions: These findings demonstrate substantially reduced neutralization of XBB.1.9 compared to WT and reveal disparities in WT immunity by age and region. The results emphasize the need for updated vaccines targeting immune-evasive variants and for tailored vaccination strategies to address regional and demographic gaps in protection.

The purpose of this study was to analyze bacterial bloodstream infections (BSIs) occurring in hospitalized pediatric hemato-oncology patients during 2012 to 2023. Data on 775 bacterial BSI episodes occurring in 456 patients (292, 63.04%, hematological malignancies and 164, 35.96%, solid tumors) were retrospectively collected and analyzed. In total, 362 (46.71%) bacterial-BSIs had profound neutropenia; 849 pathogens were isolated; gram-negative (GN) (68.78%, 584/849) were more common than gram-positive (GP) pathogens (30.86%, 262/849), P < 0.001. The most frequent GN isolates were Klebsiella spp. (20.38% of all isolates), Escherichia coli (19.20%), and Pseudomonas aeruginosa (12.01%); the most common GP isolates were Streptococcus viridans (9.19%) Enterococcus spp. (6.36%), and Staphylococcus aureus (6.12%, 21.15% MRSA). An increase in GN rates was observed in 2018–2023 versus 2012–2017 (74.16% vs. 63.22%, P = 0.001). Overall nonsusceptibility rates of Klebsiella spp. and E. coli were 80.13% and 90.07% for piperacillin, 16.76% and 9.82% for amikacin, 69.19% and 50.31% for ceftriaxone, 34.68% and 23.92% for piperacillin/tazobactam, and 8.72% and 1.85% for meropenem. Nonsusceptibility rates of Acinetobacter baumannii were 57.14% for both piperacillin/tazobactam and meropenem. The appropriateness of empiric antibiotic therapy (EAT) with piperacillin/tazobactam was lower than piperacillin/tazobactam + amikacin (62.61% vs. 90.45%, P < 0.0001). PICU admission was required in 230 (29.68%); 7-day and 30-day mortality rates were 6.36% and 14.69%, respectively. Conclusions : We report an increase in GN-BSIs and in nonsusceptibility rates of Klebsiella spp. and E. coli to several first/second-line antibiotics used in empiric antibiotic therapy. In our setting, an EAT protocol including piperacillin/tazobactam and amikacin covered most pathogens and should be considered in stable children with suspicion of BSI. What is Known: • Bloodstream infections and antibiotic resistance rates are increasing in pediatric hemato-oncology patients. What is New: • We found a dominance of gram-negative pathogens and moderate to high resistance rates of Klebsiella spp. and Escherichia coli for piperacillin/tazobactam, ciprofloxacin, and ceftriaxone. • Empiric antibiotic therapy was appropriate for 77.07% of evaluable pathogens. • The appropriateness of empiric antibiotic therapy with piperacillin/tazobactam alone was lower than that of piperacillin/tazobactam plus amikacin.