Background and Objectives: Despite long-standing MMR vaccination programmes, outbreaks of vaccine-preventable diseases continue to occur worldwide, raising concerns regarding waning immunity and susceptibility gaps in adult populations. Between 2017 and 2019 alone, WHO reported over 880,000 measles cases globally—a fourfold increase over the preceding two years—with outbreaks in both low- and high-income countries despite high childhood vaccination coverage. This study evaluated the seroepidemiology of measles, mumps, and rubella among adults in Türkiye over a nine-year period. Materials and Methods: A retrospective laboratory-based study was conducted using ELISA IgM and IgG results obtained between 2014 and 2022 at a tertiary-care university hospital. Seropositivity rates were analysed by year, age group, and sex. Temporal trends were assessed using the Cochran–Armitage trend test; factors associated with IgG seropositivity were assessed using multivariable logistic regression. Results: Among 10,407 adult test records, overall IgG seropositivity was 75.8% for measles, 94.9% for rubella, and 86.3% for mumps; IgM positivity remained low throughout (0.9%, 0.4%, and 1.9%, respectively). Measles IgG declined significantly from 78.4% in 2014–2019 to 62.6% in 2022 (p < 0.001), whereas Rubella IgG remained stable (93.2–95.7%) and Mumps IgG showed no significant temporal change. Seropositivity increased markedly with age for measles (18–29 years: 70.2% vs. ≥50 years: 93.4%; p < 0.001) and mumps (p = 0.030). Multivariable analysis confirmed that Measles IgG seropositivity was substantially lower in 2022 than in the pooled 2014–2019 period (OR = 0.432, 95% CI: 0.319–0.584, p < 0.001). Rubella seroprotection among women of reproductive age was 94.7% (95% CI: 93.9–95.5%), close to but not statistically distinguishable from the 95% population immunity benchmark used in rubella elimination frameworks. Conclusions: A significant measles immunity gap exists among younger adults in Türkiye, with Measles IgG seropositivity declining from 78.4% in 2014–2019 to 62.6% in 2022, consistent with a cohort effect whereby vaccine-era cohorts exhibit lower protection than older adults with naturally acquired immunity. Rubella immunity, by contrast, remained close to the 95% elimination benchmark throughout. These findings underscore the importance of targeted serological surveillance and evidence-based booster vaccination strategies.

Cytomegalovirus (CMV) remains a major opportunistic pathogen in individuals with HIV. The aim of this study was to investigate the seroprevalence and reactivation rates of CMV among HIV-positive individuals. A total of 300 people with HIV presenting to the Istanbul Faculty of Medicine were enrolled. Serological assessments were performed using enzyme-linked immunosorbent assay (ELISA), while molecular analyses were conducted through PCR-based methods. Sociodemographic and clinical characteristics of the patients were also evaluated. Of the participants, 90% were male, with an age range of 18-76 years. Serological testing demonstrated CMV IgG positivity in 292 patients (97.3%) and CMV IgM positivity in 11 patients (4.07%). CMV DNA was detected in 91 patients (30.3%) by molecular assays, with viral loads ranging from <150 to 2,404,678 copies/mL. CMV DNA positivity was significantly more frequent in older patients (p < 0.05) and was associated with lower CD4+ T lymphocyte counts. CMV disease was identified in 50 patients (16.7%), with organ involvement (64%) representing the most common clinical manifestation. CMV seropositivity is remarkably high in HIV-positive individuals, and reactivation rates are increased, particularly in older patients and those with advanced immunosuppression. These findings underscore the clinical relevance of routine CMV surveillance in the management of HIV infection.

OBJECTIVES:Respiratory syncytial virus (RSV) is an increasingly recognized cause of serious respiratory illness in adults, yet data from middle-income countries remain scarce. This study aimed to compare clinical outcomes of RSV and influenza virus infections in hospitalized and outpatient adults in Türkiye. METHODS:This retrospective multicenter study included 3,299 adult patients (≥18 years) with PCR-confirmed RSV (n=628) or influenza (n=2,671) from 21 centers across Türkiye between January 2022 and March 2024. The primary outcome was viral infection-related hospitalization. The secondary composite outcome was ICU admission and/or 30-day mortality among hospitalized patients. Propensity score-based overlap weighting was used to adjust for baseline differences including age, risk group, clinical severity, co-infection status, and study center. RESULTS:After overlap weighting, RSV infection was not significantly associated with increased hospitalization risk compared to influenza (OR: 0.96, 95% CI: 0.77-1.20, p=0.705). Similarly, no significant difference was observed in the composite outcome of ICU admission or 30-day mortality (OR: 1.40, 95% CI: 0.95-2.05, p=0.088). Age ≥60 years, high-risk comorbidities, and severe acute respiratory infection (SARI) presentation were the primary independent predictors of both hospitalization and worse outcomes. Bacterial or fungal co-infections and secondary infections were observed in 12.9% and 7.3% of hospitalized patients, respectively, with no significant difference between RSV and influenza groups. CONCLUSIONS:After adjustment for baseline characteristics, RSV and influenza were associated with comparable risks of hospitalization and severe clinical outcomes in adults. Host-related factors, particularly older age and underlying comorbidities, were the dominant determinants of adverse outcomes. These findings from a largely unvaccinated, middle-income country cohort highlight the need to expand RSV and influenza vaccination programs targeting high-risk adult populations.

Long COVID remains a substantial public health challenge, and the relationship between post-COVID-19 vaccination and symptom persistence remains uncertain. This prospective longitudinal study evaluated long COVID symptom trajectories according to post-COVID-19 vaccination status. Adult patients who were unvaccinated at the time of COVID-19 diagnosis were followed at 1, 3, 6, and 9 months and categorized according to vaccination status. Symptom Tool (ST) and Impact Tool (IT) scores and SARS-CoV-2 IgG antibody levels were assessed longitudinally. A total of 59 patients (mean age 43.1±14.1 years; 45.8% male) were included, of whom eight were vaccinated. The most frequently reported symptoms were memory problems, fatigue, brain fog, word-finding difficulties, and excessive sweating. Baseline characteristics were broadly comparable between groups. ST and IT scores decreased significantly over time in the overall cohort; however, no statistically significant association between vaccination status and symptom trajectories was identified. SARS-CoV-2 IgG antibody levels were higher among vaccinated participants but were not associated with symptom burden. Given the small sample size and substantial group imbalance, the study is underpowered and the findings should be interpreted cautiously. Larger prospective studies are needed to better clarify the relationship between post-COVID-19 vaccination and long COVID outcomes.

This study evaluates the effect of molnupiravir on clinical improvement, viral clearance and antibody responses of COVID-19 patients who previously developed immunity through vaccination or prior infection. This multi-center, prospective, observational study included all mild adult COVID-19 cases for whom molnupiravir was recommended during the study period. The primary outcome was hospitalization, death or new oxygen need due to COVID-19 within 28 days of follow-up. The effects of molnupiravir on viral clearance, serum biochemical tests and SARS-CoV-2 antibody levels were also assessed. A total of 844 patients (402 molnupiravir, 442 no molnupiravir) were included. The mean age was 66, 75% of them were vaccinated. The primary outcome occurred in 8 patients, with no significant difference different between propensity score-matched groups. Molnupiravir showed no effect on clinical improvement. Viral clearance was higher in the molnupiravir group on day 3, but higher in the untreated group by day 10. Serum SARS-CoV-2 antibody levels on day 28 were lower in the molnupiravir group. The effectiveness of molnupiravir in reducing hospitalization and death may be insufficient in previously immune COVID-19 patients. Additionally, molnupiravir may reduce day-28 serum SARS-CoV-2 antibody level.

BACKGROUND:Immune reconstitution in pediatric HIV infection under antiretroviral therapy (ART) is monitored by CD4 + T-cell counts and the CD4/CD8 ratio, whereas the role of double-negative T cells (DNTs; CD3 + CD4 - CD8 - ) is poorly defined. We aimed to characterize CD4 + /CD8 + T-cell dynamics and age-dependent DNT patterns. METHODS:In this retrospective cohort, 30 children were followed for 12 months after ART initiation. Flow cytometry was used to measure CD3 + , CD4 + , CD8 + and DNT subsets and the CD4/CD8 ratio; demographic, clinical and coinfection data were abstracted from medical records. RESULTS:The cohort comprised 30 children (20 boys, 10 girls; mean age 10.4 years). ART increased CD4 + and decreased CD8 + T-cell percentages, with the CD4/CD8 ratio rising from 0.73 to 1.09 and normalizing (≥1.0) in 63.3% of children. Baseline DNT levels were elevated (mean 7.0%) but declined significantly, normalizing (<5%) in adolescents, whereas children 0-5 years maintained higher residual levels. Higher DNT percentages correlated with lower CD4 + counts and an inverted CD4/CD8 ratio. Cytomegalovirus and Epstein-Barr virus viremia were common; in 3 children with dual cytomegalovirus/Epstein-Barr virus viremia, baseline CD4 + percentages were lower and DNT percentages higher, and 1 had celiac disease, suggesting that dual viremia on a background of immune-mediated disease may delay immune reconstitution. DNT% reduction showed a trend toward greater decrease with integrase inhibitor-based regimens. CONCLUSIONS:In pediatric HIV infection, CD4/CD8 ratio normalization and DNT decline depict a more nuanced immune reconstitution than CD4 + recovery alone. Age-dependent DNT trajectories support incorporating DNT monitoring as a complementary biomarker in pediatric ART management.

This study aimed to investigate prolonged severe acute respiratory syndrome coronavirus-2 polymerase chain reaction (PCR) positivity in hospitalized COVID-19 patients and evaluate the diagnostic performance of rapid antigen tests (RAgT) compared to real-time reverse transcription-PCR (RT-PCR). A prospective single-center study included 82 patients with prolonged PCR positivity (≥28 days). Serial RT-PCR and RAgT were performed at days 7 to 10, 14 to 20, and 28 to 30 post-diagnosis. Clinical data, comorbidities, and laboratory parameters (inflammatory markers, hematological, and biochemical profiles) were analyzed. Statistical analyses included sensitivity, specificity, Cohen Kappa, and receiver operating characteristic curve assessment. RAgT demonstrated 100% sensitivity and 74% specificity relative to RT-PCR, with strong agreement (Cohen κ = 0.803, P* < .001). Inflammatory markers were elevated: C-reactive protein (median 3.55 mg/L), ferritin (510 µg/L), and D-dimer (1400 ng/mL). Comorbidities were present in 62% of patients, primarily hypertension (17%) and diabetes mellitus (15%). Female patients exhibited higher inflammatory markers (C-reactive protein, fibrinogen, and lactate dehydrogenase) and anemia prevalence. Receiver operating characteristic analysis revealed excellent discriminative performance (area under the curve = 0.99). RAgT showed high sensitivity in detecting severe acute respiratory syndrome coronavirus-2 among patients with prolonged PCR positivity, suggesting potential utility in differentiating active infection from residual viral RNA. Persistent PCR positivity may correlate with noninfectious viral shedding, and RAgT could complement RT-PCR in clinical decision-making, particularly in resource-limited settings. Further multicenter studies are needed to validate these findings and assess the impact of viral variants.

OBJECTIVE:We aimed to investigate the association between CMV immunohistochemistry positivity and clinical, endoscopic, histologic, and tissue CMV PCR findings in ileocolonoscopic biopsies of inflammatory bowel disease patients, and to assess the diagnostic value of CMV immunohistochemistry as a reflex test during routine histopathologic evaluation. MATERIAL AND METHODS:We conducted a retrospective analysis of 191 patients (136 ulcerative colitis, 55 Crohn`s disease) between 2018 and 2021. We analyzed clinical data, endoscopic Mayo scores, histologic activity (Simplified Geboes Score), cytopathic changes, CMV immunohistochemistry and tissue CMV PCR results. RESULTS:CMV immunohistochemistry was positive in 32.4% of cases, significantly associated with ulcerative colitis (p=0.003), symptomatic presentation (p=0.001), extensive colonic involvement (p < 0.001), high histologic activity scores (p < 0.001), and ulceration (p < 0.001). Notably, 74.2% of CMV immunohistochemistry-positive cases had no preliminary clinical suspicion of CMV infection. Viral cytopathic changes were identified in only 30.6% of immunopositive cases on hematoxylin-eosin staining. CMV immunohistochemistry showed a significant correlation with tissue PCR (p < 0.001), although some discordant cases occurred. The PCR-positive group had significantly higher immunopositive cell counts compared to the PCR-negative group (p < 0.001). The number of biopsy fragments did not affect CMV detection by immunohistochemistry. CONCLUSION:While evaluating endoscopic biopsies of patients with inflammatory bowel disease, CMV immunohistochemistry assessment as a reflex test may be considered by the pathologist-even in the absence of identifiable viral cytopathic effects with hematoxylin-eosin- particularly when severe histologic inflammation is present. Although the clinical significance of CMV immunohistochemistry could not be fully determined in this study, this approach may increase the likelihood of detecting CMV infection and, in the appropriate clinical context, could contribute to timely diagnosis and management.

Aims: This study retrospectively evaluates the serological (CMV IgM and IgG) and molecular (CMV DNA PCR) test results of patients admitted to İstanbul Faculty of Medicine Hospital between 2021 and 2023 due to suspected cytomegalovirus (CMV) infection. The aim is to assess the diagnostic value of combining serological and molecular methods and to analyze CMV positivity across age and gender groups. Methods: This cross-sectional observational study included 1.649 patients who underwent CMV testing (CMV IgM, CMV IgG, and/or CMV DNA PCR) at the Medical Microbiology Laboratory of İstanbul Faculty of Medicine between January 1, 2021, and December 31, 2023. Serological tests were performed using ELISA (Vircell, Spain), and CMV DNA was quantified using real time PCR (QIAsymphony/Artus CMV QS-RGQ and cobas® 6800). Data were anonymized and analyzed statistically using SPSS v26.0. Mann-Whitney U, Chi-square, McNemar, and ROC tests were applied; p0.05), CMV DNA positivity varied significantly across age groups (p

The aim of the study was to determine the prevalence rates of respiratory pathogens using syndromic tests and also to show which respiratory viruses were detected in suspected cases, especially during and after the pandemic period. A total of 1984 different respiratory tract samples from various departments were included and studied with the QIAstat-Dx device in 2021-2023. The samples were studied with the QIAstat-Dx1 Respiratory SARS-CoV-2 Panel. The kit used was a fully automated, multiplex syndromic test that detected SARS-CoV-2 and 21 other respiratory tract pathogens. As a result of the study, the prevalence of Rhinovirus/Enterovirus (RV/EV) (18.59%), RV/EV-SARS-CoV-2 (42.74%), SARS-CoV-2 (5.04%), and Influenza A Virus (IAV) (5.59%) agents was found to be higher than other agents during the period investigated. Among the 1984 patients examined, 959 (48.33%) had a single viral agent, 156 (7.86%) had double coinfection, 11 (0.55%) had triple coinfection and 1 patient had quadruple coinfection. Nearly half of the patients had a straightforward infection, which helps clinicians in directing specific treatment methods. The study results demonstrate that during the pandemic period, the detection of respiratory pathogens such as SARS-CoV-2 and RV/EV was not only critical for accurate diagnosis but also served as an important indicator of the broader epidemiological trends in respiratory infections. The seasonal distribution showed that while RV/EV was frequently present, its coinfection with SARS-CoV-2 was notably observed only in the first trimester. In light of our findings showing high rates of SARS-CoV-2 and RV/EV detection, along with diverse patterns of coinfection in clinical samples, such comprehensive testing not only assists in rapid diagnosis but also informs public health strategies by reflecting the evolving landscape of respiratory infections in the pandemic and post-pandemic era.

Objectives:In the early years of defining Human Immunodeficiency Virus (HIV) and Acquired Immune Deficiency Syndrome (AIDS), its prevalence among homosexual men gave rise to prejudices, the development of immunodeficiency, and lethal infections, causing fear and panic in society. Unethical approaches hindered patients from accessing healthcare services, creating substantial barriers from diagnosis to treatment in the fight against HIV/AIDS. This study aimed to explore the diagnostic significance of an ethical approach toward HIV-positive patients, guided by demographic data. Methods:Demographic patient characteristics and stigmatization during HIV testing were assessed using a 47-question questionnaire. The research commenced on 01/05/2019 and concluded on 01/05/2020, with questionnaires administered online during the COVID-19 pandemic. Statistical analysis employed the SPSS 21.0 (Armonk, New York: IBM Corp.) package, cross-tabulating survey questions and comparing answers using the Chi-square test. Additionally, multivariate logistic regression analysis was conducted to identify factors associated with perceptions of ethical violations. Results:The study included 121 participants, with 91% identifying as male, 3% as female, 1.7% stating another gender identity, 2.5% declining to specify, and 1.7% not responding to the question. Participant ages ranged from 19 to 66 years, with a mean of 37.9±10.5. Prior to HIV testing, written consent was obtained from 62.8% of patients, while 37.2% declined to provide consent. Among those who consented, 31.4% reported feeling insufficiently informed about the procedure. During result disclosure, 25.6% found the approach impolite, with abrupt and insufficient information. Additionally, 24% noted the presence of a third person during disclosure, while 25.6% reported breaches of patient confidentiality. Logistic regression analysis revealed that age was the only statistically significant factor associated with perceived ethical violations (p=0.010). Conclusion:This study highlights critical ethical deficiencies in Türkiye's HIV testing procedures, with 31.4% of patients reporting inadequate consent and 25.6% experiencing unprofessional result disclosure. These findings underscore the urgent need for patient-centered protocols to ensure ethical standards and reduce stigma.

Human pegivirus (HPgV) is transmitted through sexual or parenteral exposure and is common among patients receiving blood products. HPgV is associated with lower levels of human immunodeficiency virus (HIV) RNA and better survival among HIV-infected patients. This study aimed to investigate the prevalence of HPgV and determine its subtypes in HIV-infected individuals living in Istanbul, which has the highest rate of HIV infection in Türkiye. Total RNA extraction from plasma, cDNA synthesis, and nested PCR were performed for HPgV on plasma samples taken from 351 HIV-1-infected patients. The HPgV viral load was quantified on HPgV-positive samples. HPgV genotyping was performed by sequencing the corresponding amplicons. In the present study, the overall prevalence of HPgV RNA in HIV-infected patients was 27.3%. HPgV subtypes 1, 2a, and 2b were found, with subtype 2a being the most frequent (91.6%). Statistical analysis of HIV-1 viral load on HPgV viral load showed an opposing correlation between HIV-1 and HPgV loads. In conclusion, these data show that HPgV infection is common among HIV-positive individuals in Istanbul, Türkiye. Further comprehensive studies are needed to clarify both the cellular and molecular pathways of these two infections and to provide more information on the effect of HPgV on the course of the disease in HIV-infected individuals.

Background BK polyomavirus (BKPyV) is an important cause of nephropathy, graft dysfunction and loss in patients receiving immunosuppressive therapy after solid organ transplantation, especially kidney transplantation. However, the full spectrum of BKPyV-related kidney diseases in immunocompromised patients remains unclear. The aim of our study was to evaluate the frequency of BKPyV-DNA in blood and urine in patients who received immunosuppressive treatment due to kidney diseases other than kidney transplantation and to compare healthy controls. Methods A total of 46 (25 female) children, who were using immunosuppressive treatment and were under follow-up due to kidney diseases at the pediatric nephrology outpatient clinic and 28 (13 female) healthy controls, were included in the study. BKPyV quantitation was performed in urine and serum samples by real time polymerase chain reaction (PCR). Results Patient group and control group mean ages were 11.3±4.6 and 9.92±4.5 years respectively. There was no statistical difference between the patient and control groups regarding age and sex distribution (p>0.05). Twenty-four (52.2%) patients were receiving methylprednisolone, 14 (30.4%) patients were receiving dual, 1 (2.2%) patient was receiving triple immunosupressive therapy and 7 (15.2%) patients were receiving single immunosupressive therapy other than steroid. BKPyV-DNA was detected in the urine samples of 2 (4.35%) patients while there were no BKPyV-DNA positivity in plasma samples. One of these patients was being followed up with the diagnosis of systemic lupus erythematosus (SLE). Until the sample date, she had received methylprednisolon pulses, oral methylprednisolon, intravenosus immunglobulin, intravenousus cyclophosphamide, mycophenolat mofetil and rituximab. The patient’s current treatment was cyclosporin and oral methylprednisolon. The second patient was diagnosed with steroid-dependent nephrotic syndrome. He had recevied cylophosphamid previously and his current treatment was oral methylprednisolon. Remarkably, both patients had a history of cyclophosphamide treatment. There were no positivity in the plasma and urine samples of the healthy control group. Conclusion The use of steroids alone in immunosuppressive therapy does not appear to be an important risk factor for BKPyV reactivation. It does not seem necessary to perform plasma and urine BKPyV-DNA screening in pediatric patients not receiving intensive immunosuppressive therapy. It has been thought that BKPyV reactivation may be more frequent, especially if the underlying disease is SLE or if cyclophosphamide is used as an immunosuppressive, and BKPyV screening may be performed in these patients. The absence of positivity in any patient in our healthy control group suggests that BKV viruria and viremia are very low in healthy children.

Aim: Respiratory viruses significantly impact public health, contributing to high morbidity and mortality rates in both children and adults. This study evaluates the distribution and incidence of respiratory tract viruses in our hospital from 2019 to 2022, focusing on changes post-COVID-19 pandemic. Material and Methods: Utilizing molecular methods, we analyzed nasopharyngeal swabs with the FTD Respiratory Pathogens 21 kit and the QIAStat Dx Respiratory Panel kit at Istanbul Faculty of Medicine. A total of 1186 viruses were detected in 2488 samples (47.6% of the total) examined with the FTD Respiratory Pathogens 21 kit between 2019 and 2022. Results: It was determined that the detection rates were 52.8% in 2019, 44.3% in 2020, 50.0% in 2021, and 40.0% in 2022. Notable changes in prevalence were observed for pandemic influenza A (IAV-H1N1pdm2009), parainfluenza virus (PIV)-3, rhinovirus (RV), and respiratory syncytial virus (RSV)-A/B (p < 0.05). RV consistently showed the highest detection rates across all years (17.6% to 7.9%). Additionally, 1276 viruses were detected in 1496 samples using the QIAStat DX kit, with 91.3% positivity in 2021 and 78.6% in 2022, highlighting the kit’s effectiveness in rapid diagnosis. Conclusions: This study enhances understanding of respiratory virus epidemiology during and after the pandemic, emphasizing the need for ongoing surveillance and strategic public health measures to address the evolving landscape of respiratory infections.

Neutralizing antibodies plays a primary role in protective immunity by preventing severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) from entering the cells. Therefore, characterization of antiviral immunity is important for protection against SARS-CoV-2. In this study, the neutralizing effect of the anti-SARS-CoV-2 S1 protein IgG, which was detected using the chemiluminescence microparticle immunoassay (CMIA)-based SARS-CoV-2 IgG II Quant (Abbott, Waukegan, IL, USA) test in SARS-CoV-2 infected and/or vaccinated individuals, was investigated with a surrogate virus neutralization test (sVNT). In total, 120 Seropositive individuals were included in this study. They were divided into two groups: Vaccinated (n = 60) and Vaccinated + Previously Infected (n = 60). A commercial sVNT, the ACE2–RBD Neutralization Test (Dia.Pro, Milan, Italy), was used to assess the neutralizing effect. The assay is performed in two steps: screening and titration. The screening showed positive results in all seropositive samples. Low titration in 1.7%, medium titration in 5%, and high titration in 93.3% of the Vaccinated group, and medium titration in 1.7% and high titration in 98.3% of the other group, as obtained from the ACE2-RBD titration test. A strong positive and significant correlation was found between the SARS-CoV-2 IgG II Quant test and the ACE2-RBD titration test at the 1/32 titration level for both groups (p < 0.001 for both). This study shows that the SARS-CoV-2 IgG detected using the CMIA method after SARS-CoV-2 infection and/or vaccination has a high neutralizing titration by using the sVNT. In line with these data, knowledge that seropositivity determined by CMIA also indicates a strong neutralizing effect contributes to countrywide planning for protecting the population.

In the original publication [...].

Objective: Respiratory viruses are an important cause of morbidity and mortality in pediatric hematology oncology patients. We aimed to determine the infection rate, clinical and epidemiological characteristics of respiratory viruses in pediatric patients with hemato-oncological malignancy, aplastic anemia and congenital neutropenia and to show how these viruses affect the primary disease course and treatment. Methodology: Between August 2015 and December 2018, 97 patients aged between 5 months and 215 months who were admitted to Istanbul University, Istanbul Faculty of Medicine, Department of Pediatric Haematology-Oncology with acute respiratory tract infection findings and diagnosed with Haemato-Oncological Malignancy, Congenital Neutropenia, Aplastic Anaemia and who had viral respiratory panel were retrospectively analysed. In the viral respiratory panel test, nasal swab samples of the patients were evaluated by RT-multiplex PCR method. SPSS (Statistical Package for the Social Sciences) 22.0 programme was used for statistical analyses Results: A total of 97 patients, 52 males (53.6%) and 45 females (46.4%), aged between 5 months and 215 months (78.81±60.17 months, median 60 months) were included in the study. The most common viral respiratoty panel (VRP) positivity was observed between 5 months and 208 months and the mean age was 85.49±61.73 months (median=81 months). Although 44.3% (n=43) of the patients presented in winter and 23.7% (n=23) in autumn, VRP positivity was more common in patients presenting in spring (n=43, 70%) and winter (n=22, 51.2%) seasons. When the VRP results of the patients were analysed; 50.5% (n=49) were positive; 39.2% (n=38) were monoinfection, 11.3% (n=11) were co-infection) and 49.5% (n=48) were negative. When we looked at the VRP results, rhinovirus (hRV) was the most common virus with a frequency of 22.4% (n=11). Other viruses were Respiratory Synsititial Virus (RSV) A/B (14.2% n=7), Parainfluenza (14.2% n=7), Influenza (8.2% n=4), Coronavirus (8.2% n=4), Metapneumovirus (2.1% n=1), Mycoplasma pneumonia (6.1% n=3). Among the co-infections seen in a total of 11 patients, hRV and RSV A/B were the most common viruses accompanying other viruses with a rate of 63.6% (n=7). Among a total of 67 patients who were in various stages of CT and whose treatment was completed, the most common VRP positivity was seen in patients in the induction phase with a rate of 28.3% (n=19). Of the 12 patients with co-infection, 5 (41.6%) were in the induction phase. Cough (n=59 60.8%) and fever (n=47 48.5%) were the most common presenting complaints, accompanied by wheezing (n=17 17 17.5%), respiratory distress (n=11 11.3%), diarrhoea/vomiting (n=9 9.3%) and muscle pain (n=9 9.3%). VRP was positive in 43.9% of patients presenting with fever. The most common hRV virus was found most frequently in spring and winter seasons. Viral respiratory infection positivity was most frequently seen in ALL (n=16 33.3%), second most frequently in Hodgkin's Lymphoma (n=5 10.5%) and Neuroblastoma (n=5 10.5%). Among the patients, upper respiratory tract infection (URTI) (74.2%, n=72) was more common than lower respiratory tract infection (LRTI) (25.8%, n=25). The rate of LRTI in co-infections (28.0%, n=14) was higher than the rate of URTI (6.9%, n=5) and was statistically significant (p=0.021). When hemogram and biochemistry results were analysed, although neutropenia (50.5%) and lymphopenia (50.5%) were observed at a high rate in patients with positive VRI, they were not statistically significant when compared with VRP positivity. Of the patients with VRP positivity (50.5% n=49), 34.6% (n=17) required hospitalisation due to viral respiratory infection. Of the patients included in the study, 4 patients need intensive care unit due to bacterial pneumonia (Mycoplasma pneumonia and Pneumocystis jireovici), bleeding into a mass (hepatoblastoma) and pericardial effusion (peripheric T cell lymphoma). In 7 patients whose chemotherapy duration was prolonged, the duration of treatment prolongation ranged between 4 and 60 days (mean 19.29±20.69 and median 10 days). No VRI-related mortality was observed among the patients during the follow-up period. Conclusion: Identification of respiratory viruses in pediatric hematology oncology patients contributes to the management of their primary disease.

The aim of this study was to investigate the reinfection rates and characteristics of SARS-CoV-2 in individuals with SARS-CoV-2 RNA present in their clinical specimens for COVID-19. Our data from the COVID-19 Laboratory of Istanbul University were analyzed for 27,240 cases between 27 March 2020 to 8 February 2022. Demographic characteristics, vaccination statuses, comorbidities, and laboratory findings were evaluated in cases with suspected reinfection, as determined by the presence of SARS-CoV-2 RNA at a rate of 0.3% in clinical specimens. When comparing laboratory values, leukocyte counts were lower in the second and third infections compared with the first infection (p = 0.035), and neutrophil counts were lower in the second infection (p = 0.009). Symptoms varied, with coughing being common in the first infection and malaise being common in subsequent infections. These results suggest that it is important to continue to monitor reinfection rates and develop strategies to prevent reinfection. Our results also suggest that clinicians should be aware of the possibility of reinfection and monitor patients for recurrent symptoms.

Objective: The COVID-19 pandemic and annual influenza epidemic are responsible for thousands of deaths globally. This study was conducted to identify epidemiological aspects while demonstrating features that distinguish between influenza infection and COVID-19 disease in terms of clinical manifestations, laboratory, and prevention. Methods: The patients hospitalized with confirmed influenza between October 2009-May 2014 (n=344) and with confirmed COVID-19 between April 2020-June 2021 (n=251) were enrolled in this study. Results: The age of the patients with influenza infection was statistically significantly younger than the patients with SARS-CoV-2 infection (mean age 6 +/- 5.3 years versus 13.0 +/- 5.3 years, p <0.001). Fever, cough, and myalgia were the more common symptoms of influenza (p< 0.001; p<0.001, p=0.02). It was found that in cases of COVID-19 (n=55/251, 21.9%), headache complaints were more common at admission. Lymphopenia (n=89/251 35.4%) in COVID-19 and CRP elevation detected in influenza cases (n=201/344 58.4%) were statistically significant (p=0.01/p<0.001). The mean hospital stay was 6 +/- 5 days (1-90 days) in influenza and 1 +/- 4 (1-64 days) in COVID-19 (p< 0.001). The radiological investigations were less necessary in children with COVID-19 because of the lower overall incidence of infected, symptomatic, and severe cases and the lower presence of cough and respiratory symptoms compared to adults. Conclusions: As the clinical and epidemiological features of COVID-19 have many parallels with influenza, it is important to ensure optimal management of both respiratory diseases as we expect that co-circulation will continue. Clinical findings in children are not sufficient for a definitive diagnosis, so it should be supported by a viral diagnosis test.