Differential Inflammatory Responses in Adult and Pediatric COVID-19 Patients: Implications for Long-Term Consequences and Anti-Inflammatory Treatment.

BACKGROUND COVID-19 manifests with varying degrees of severity across different age groups; adults typically experience more severe symptoms than children. Matrix metalloproteinases (MMPs), known for their role in tissue remodeling and immune responses, may contribute to the pathophysiological disparities observed between these groups. We sought to delineate differences in serum MMP profiles between adult and pediatric COVID-19 patients, assess the influence of anti-inflammatory treatment on MMP levels, and examine potential implications for long-term consequences. MATERIAL AND METHODS Serum samples from adult and pediatric COVID-19 patients, alongside controls, were analyzed for MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-10, MMP-12, MMP-13, EMMPRIN, TNF-alpha, TIMP-1, TIMP-2, TIMP-3, and TIMP-4. A subset of adult patients received treatment with glucocorticoids, tocilizumab, and convalescent plasma, and MMP levels were compared with those of untreated patients. RESULTS Elevated levels of MMP-1, MMP-7, TIMP-1, and TIMP-2 were observed in adult and pediatric patients. Adult patients displayed higher concentrations of MMP-3, MMP-8, MMP-9, TNF-alpha, and TIMP-4 than children. Post-treatment reduction in MMP-1, MMP-8, MMP-9 levels was observed, with median decreases from 21% to 70%. MMP-3 and MMP-7 remained largely unchanged, and MMP-2 concentrations increased after treatment. Notably, anti-inflammatory treatment correlated with reduced post-treatment MMP levels, suggesting potential therapeutic benefit. CONCLUSIONS Distinctive inflammatory responses in COVID-19 were evident between adults and children. While certain MMPs exhibited post-treatment reduction, the persistence of elevated levels raises concerns about potential long-term consequences, including lung fibrosis. Our findings emphasize the need for personalized treatment strategies and further investigation into the dynamics of MMP regulation in COVID-19.

Diagnostic Precision in Lyme borreliosis: Assessing VlsE and C6 Antigens in a Pediatric Cohort.

(1) Background: Lyme borreliosis (LB) is a tick-borne disease known for its diagnostic challenges. Conventional two-tiered testing (CTTT) for antibodies is time-consuming, has low sensitivity in the early stages of disease, and sometimes generates false-positive IgM immunoblots. To tackle this issue, modified two-tiered testing (MTTT) was introduced, incorporating recombinant VlsE and C6 antigens to enhance diagnostic accuracy. (2) Methods: In this prospective study, we enrolled children exhibiting symptoms indicative of LB. We collected serum samples at various intervals and subjected them to analysis using standard enzyme immunoassays. We then compared these results with the outcomes from the VlsE and C6 assays. (3) Results: In our study, all 33 patients displaying erythema migrans (EM), a characteristic symptom of LB, exhibited positive responses to the C6 antigen. This finding underscores the potential utility of the C6 antigen as a reliable diagnostic tool for LB. Additionally, we observed a significant reduction in anti-VlsE antibody levels following antibiotic treatment in EM patients. (4) Conclusions: The utilization of recombinant VlsE and C6 antigens in LB diagnostics and monitoring has yielded promising results. Nonetheless, it is imperative for clinicians to exercise caution and interpret results in conjunction with clinical findings, considering the dynamic nature of medical guidelines. Even with recombinant antigen tests, some children with EM tested negative, highlighting the importance of clinical diagnosis for treatment decisions. Furthermore, clinicians should be mindful of the possibility of persistently positive VlsE/C6 test results during LB treatment monitoring.

Clinical Presentation and Co-Detection of Respiratory Pathogens in Children Under 5 Years with Non-COVID-19 Bacterial and Viral Respiratory Tract Infections: A Prospective Study in Bialystok, Poland (2021-2022).

BACKGROUND Respiratory tract infections (RTIs) in children often involve a complex interplay between viruses and bacteria. This study aimed to evaluate clinical presentation in children under 5 years old diagnosed with non-COVID-19 bacterial and viral respiratory tract co-infections between October 2021 and May 2022 in Bialystok, Poland. MATERIAL AND METHODS We recruited 100 children under 5 years with RTIs who tested negative for SARS-CoV-2. Nasopharyngeal swabs were screened for 19 viruses and 7 bacterial strains using molecular assays. RESULTS Viral pathogens were detected in 71% of patients and bacterial pathogens were detected in 59%. The most common pathogens were Haemophilus influenzae (n=48), rhinoviruses (n=32), and Streptococcus pneumoniae (n=30). Single pathogens were detected in 36%, dual in 37%, triple in 15%, and quadruple in 2%. Bacterial pathogens were co-detected with viruses in 40 cases, mostly with rhinoviruses (n=15). Two different viruses were found in 14 children and the most common co-detection was adenovirus with rhinovirus (n=5); dyspnea (63% vs 11%) and wheezing (75% vs 22%) were more common in children with human bocavirus. Fever was a common symptom in children with human adenovirus (88% vs 58%). Detection of bacteria and multiple detections were more common in day-care attendees, but were not associated with clinical picture of RTI. CONCLUSIONS Consistent with previous studies, we found a high prevalence of rhinoviruses, despite ongoing implementation of non-pharmaceutical interventions to contain the COVID-19 pandemic. Co-detection of 2 different respiratory pathogens was frequent, but we found no evidence that this was associated with the severity of infections.

Seroprevalance of anti-SARS-CoV-2 antibodies in the IgG class in hospitalized children in the north-eastern part of Poland in 2021.

Introduction: In children, SARS-CoV-2 infection may manifest with symptoms of fever, cough, muscle pain, diarrhea or waste smell and taste. However, in most cases it is mild or asymptomatic. Determination of the level of anti-SARS CoV-2 IgG antibodies in children enables to assess retrospectively the incidence of the SARS-CoV-2 infection among children. Aim of the study: The aim of the research was to analyze the results of anti-SARS-CoV-2 antibodies in the IgG class contained in children hospitalized in north-eastern Poland in 2021. Material and methods: The material for the study was venous blood collected once from children hospitalized in Children's University Hospital in Bialystok in 2021. The results obtained from 615 children aged from 1 month to 11 years were analyzed. Determination of the level of antibodies was performed using the automated SARS-COV-2 IgG II test on the VIDAS® analyzer. Results: The analysis of the results of the anti-SARS-CoV-2 IgG value showed that half of children (52%, n=319) had contact with SARS-CoV-2 virus of which approximately 15% (n=47) had documented infection with this virus. There was no difference in the frequency of infections among boys and girls, antibodies were detected in 51% and 53%, respectively. The highest percentage of positive results was observed in children aged 7 to 10 years, 62% (91/147). The least children with a positive result were in the group below 1 year of age, 24% (4/17). High values of the antibody index (>15.00) were most often found among younger children, aged 1-2 years. Conclusions: The presented results showed that infection with the SARS-CoV-2 virus does not depend on the sex of children but the value of anti-SARS-CoV-2 IgG antibodies decreased with the age of the child.

The Role of Adipokines in the Pathologies of the Central Nervous System.

Adipokines are protein hormones secreted by adipose tissue in response to disruptions in physiological homeostasis within the body's systems. The regulatory functions of adipokines within the central nervous system (CNS) are multifaceted and intricate, and they have been identified in a number of pathologies. Therefore, specific adipokines have the potential to be used as biomarkers for screening purposes in neurological dysfunctions. The systematic review presented herein focuses on the analysis of the functions of various adipokines in the pathogenesis of CNS diseases. Thirteen proteins were selected for analysis through scientific databases. It was found that these proteins can be identified within the cerebrospinal fluid either by their ability to modify their molecular complex and cross the blood-brain barrier or by being endogenously produced within the CNS itself. As a result, this can correlate with their measurability during pathological processes, including Alzheimer's disease, amyotrophic lateral sclerosis, multiple sclerosis, depression, or brain tumors.

Associations of the cerebrospinal fluid lymphocyte population with a clinical presentation of tick-borne encephalitis.

In tick-borne encephalitis (TBE), lymphocytes infiltrating central nervous system are indispensable for the infection control, but also potentially immunopathogenic. To clarify their roles, we have evaluated cerebrospinal fluid (CSF) count of the main lymphocyte populations (considered as a proxy of the brain parenchyma lymphocytic infiltrate) in TBE patients and analyzed if they associate with clinical presentation, blood-brain barrier disruption and intrathecal antibody synthesis. We have studied CSF from 96 adults with TBE (50 with meningitis, 40 with meningoencephalitis, 6 with meningoencephalomyelitis), 17 children and adolescents with TBE and 27 adults with non-TBE lymphocytic meningitis. Th CD3+CD4+, Tc CD3+CD8+, double positive T CD3+CD4+CD8+, B CD19+ and NK CD16+/56+ cells were counted cytometrically with a commercial fluorochrome-stained monoclonal antibody set. The associations between the counts and fractions of these cells and clinical parameters were analyzed with non-parametric tests, p<0.05 considered significant. The TBE patients had lower pleocytosis with similar proportions of the lymphocyte populations compared to non-TBE meningitis. The different lymphocyte populations correlated positively with one another, as well as with CSF albumin, IgG and IgM quotients. The higher pleocytosis and expansion of Th, Tc and B cells associated with a more severe disease and neurologic involvement: Th with encephalopathy, myelitis and weakly with cerebellar syndrome, Tc with myelitis and weakly with encephalopathy, B with myelitis and with at least moderately severe encephalopathy. The double-positive T lymphocytes associated with myelitis, but not with other forms of CNS involvement. The fraction of double positive T cells decreased in encephalopathy and the fraction of NK in patients with neurologic deficits. In children with TBE, Tc and B counts were increased at the expense of Th lymphocytes in comparison with adults. The concerted intrathecal immune response, involving the main lymphocyte populations, increases with the clinical severity of TBE, with no evidently protective or pathogenic elements distinguishable. However, the particular populations including B, Th and Tc cells associate with different, though overlapping, spectra of CNS manifestations, suggesting they may be specifically related to TBE manifesting as myelitis, encephalopathy and cerebellitis. The double-positive T and NK cells do not expand evidently with severity and may be most closely associated with the protective anti-TBEV response.

Clinical Course and Severity of COVID-19 in 940 Infants with and without Comorbidities Hospitalized in 2020 and 2021: The Results of the National Multicenter Database SARSTer-PED.

This study aimed to analyze the differences in severity and clinical characteristics of COVID-19 in infants hospitalized in Poland in 2021, when the dominance of variants of concern (VOCs) alpha and delta was reported, compared to 2020, when original (wild) SARS-CoV-2 was dominant (III-IV vs. I-II waves of the pandemic, respectively). In addition, the influence of the presence of comorbidities on the clinical course of COVID-19 in infants was studied. This multicenter study, based on the pediatric part of the national SARSTer database (SARSTer-PED), included 940 infants with COVID-19 diagnosed between March 1, 2020, and December 31, 2021, from 13 Polish inpatient centers. An electronic questionnaire, which addressed epidemiological and clinical data, was used. The number of hospitalized infants was significantly higher in 2021 than in 2020 (651 vs. 289, respectively). The analysis showed similar lengths of infant hospitalization in 2020 and 2021, but significantly more children were hospitalized for more than 7 days in 2020 (p < 0.009). In both analyzed periods, the most common route of infection for infants was household contact. There was an increase in the percentage of comorbidities, especially prematurity, in children hospitalized in 2021 compared to 2020. Among the clinical manifestations, fever was predominant among children hospitalized in 2021 and 2020. Cough, runny nose, and loss of appetite were significantly more frequently observed in 2021 (p < 0.0001). Severe and critical conditions were significantly more common among children with comorbidities. More infants were hospitalized during the period of VOCs dominance, especially the delta variant, compared to the period of wild strain dominance, even though indications for hospitalization did not include asymptomatic patients during that period. The course of COVID-19 was mostly mild, characterized mainly by fever and respiratory symptoms. Comorbidities, particularly from the cardiovascular system and prematurity, were associated with a more severe course of the disease in infants.

The Influence of SARS-CoV-2 Variants B.1.1.7 and B.1.617.2 on a Different Clinical Course and Severity of COVID-19 in Children Hospitalized in 2021 Compared With 2020.

BACKGROUND: This study aimed to analyze the differences in the epidemiologic and clinical characteristics of coronavirus disease 2019 (COVID-19) in children hospitalized in 2021, when the severe acute respiratory syndrome coronavirus 2 variants B.1.1.7 (alpha) and B.1.617.2 (delta) dominated, compared with 2020. METHODS: In this multicenter study based on the pediatric part of the national SARSTer register (SARSTer-PED), we included 2771 children (0-18 years) with COVID-19 diagnosed between March 1, 2020, and December 31, 2021, from 14 Polish inpatient centers. An electronic questionnaire, which addressed epidemiologic and clinical data, was used. RESULTS: Children hospitalized in 2021 were younger compared with those reported in 2020 (mean 4.1 vs. 6.8 years, P = 0 .01). Underlying comorbidities were reported in 22% of the patients. The clinical course was usually mild (70%). A significant difference in the clinical course assessment between 2020 and 2021 was found, with more asymptomatic patients in 2020 and more severely ill children in 2021. In total, 5% of patients were severely or critically ill, including <3% of the participants in 2020 and 7% in 2021. The calculated mortality rate was 0.1% in general and 0.2% in 2021. CONCLUSION: Infections with severe acute respiratory syndrome coronavirus 2 variants alpha and delta lead to a more severe course of COVID-19 with more pronounced clinical presentation and higher fatality rates than infection with an original strain. Most of the children requiring hospitalization due to COVID-19 do not have underlying comorbidities.

Knowledge, Attitudes, and Behaviors Regarding Lyme Borreliosis Prevention in the Endemic Area of Northeastern Poland.

(1) Background: The incidence of Lyme borreliosis (LB) is increasing in Europe. The new LB vaccine is still in clinical development, thus the dissemination of knowledge about the disease is essential. We assessed the knowledge, attitudes and preventive practices (KAP) against tick-borne diseases (TBDs) of people living in the endemic area in northeastern Poland. (2) Methods: We surveyed 406 adults using a 37-item anonymous paper survey. The data were analyzed with regression models. (3) Results: The two most popular knowledge sources were the Internet and doctors, selected by 77.8% and 53.4%, respectively. Respondents felt moderately knowledgeable about TBDs and tick bite prophylaxis (median scores 5/10, and 6/10, respectively), considered TBDs to be a significant health threat (median 8/10), attributed high risk to tick mouthparts remaining in the skin after tick removal (median 10/10), and shared multiple misconceptions regarding LB transmission, symptoms, and management. General knowledge scores (GKS) about TBDs and tick protection practices scores (TPS) were moderate (65.0%; IQR, 55.8−71.7%, 63.6%; 54.5−72.7%, respectively). Only 48.0% had a positive attitude towards TBE vaccination. A recent tick-bite was associated with higher GKS (OR, 2.55; 95% CI, 1.27−5.10; p = 0.008), higher TPS (OR 4.76, 95% CI, 2.0−11.1; p < 0.001), and a positive attitude towards TBE vaccine (OR 2.10, 1.07−4.10, p = 0.030). A positive vaccine attitude was also associated with obtaining TBD knowledge from doctors and other verified sources (OR, 2.654, 1.66−4.23; p < 0.001). Age, place of residence, and frequent exposure to ticks in green areas were not associated with GKS, TPS, nor vaccine attitude. (4) Conclusions: Increased risk perceptions are associated with adoption of behaviors preventing TBDs. Medical professionals play an important role in communicating knowledge about TBDs. There is a need to revise current communication strategies with respect to tick bites and prevention of LB and other TBDs.

The Prevalence of Asymptomatic Infections with Tick-Borne Encephalitis Virus and Attitude towards Tick-Borne Encephalitis Vaccine in the Endemic Area of Northeastern Poland.

In Poland, tick-borne encephalitis (TBE) vaccination rate is low despite high incidence of severe infections with TBE virus (TBEV). However, infection with TBEV can be asymptomatic or mild, which makes the total number of cases difficult to assess. We aimed at assessing asymptomatic TBEV infections and describing attitudes towards the TBE vaccine. We studied 298 healthy adult blood donors and 180 children from the TBE endemic area of northeastern Poland for the presence of anti-TBEV IgG antibodies. We also surveyed a separate cohort of 444 adults. Thirty-eight blood donors (13%) and 38 survey respondents (9%) reported a history of a prior anti-TBEV vaccination. Forty respondents (9%) reported vaccinating their child in the past. Fourteen unvaccinated blood donors (5%) and four children (2%) were seropositive for specific anti-TBEV antibodies, suggesting a history of an undiagnosed TBEV infection. In the surveyed cohort, 130 (32%) expressed their intention to be vaccinated and 144 (36%) expressed their intention to vaccinate their child. This intention was significantly higher in respondents with a recent tick-bite, a diagnosis of tick-borne disease in a close relative, and in males. Our study shows that asymptomatic TBEV infections are common. The acceptance of TBE vaccine is low, but might be increased by communicating risks associated with tick bites.

The Detectability of the Viral RNA in Blood and Cerebrospinal Fluid of Patients with Tick-Borne Encephalitis.

BACKGROUND: The detection rate of viral RNA in tick-borne encephalitis (TBE) is low and variable between studies, and its diagnostic/prognostic potential is not well defined. We attempted to detect RNA of TBE virus (TBEV) in body fluids of TBE patients. METHODS: We studied 98 adults and 12 children with TBEV infection, stratified by the disease phase and presentation. EDTA blood and cerebrospinal fluid (CSF) samples were obtained upon hospital admission. RNA was extracted from freshly obtained plasma, concentrated leukocyte-enriched CSF, and whole blood samples, and real time PCR was performed with a Rotor-Gene Q thermocycler. RESULTS: TBEV RNA was detected in (1) plasma of one (of the two studied) adult patients with an abortive infection, (2) plasma of two (of the two studied) adults in the peripheral phase of TBE, and (3) plasma and blood of an adult in the neurologic phase of TBE presenting as meningoencephalomyelitis. No CSF samples were TBEV RNA-positive. CONCLUSIONS: The detection of TBEV RNA in blood might be diagnostic in the peripheral phase of TBE. The lack of TBEV RNA in the CSF cellular fraction speaks against TBEV influx into the central nervous system with infiltrating leukocytes and is consistent with a relatively low intrathecal viral burden.

COVID-19 infections in infants.

The study aimed to analyse the clinical course of COVID-19 in 300 infants, selected from 1283 children diagnosed with COVID-19 between March and December 2020, registered in the SARSTerPED multicenter database. Most of the infants were registered in October and November 2020. 44% of the group were girls, and 56% were boys. At diagnosis, the most common symptoms were fever in 77% of the children, cough in 40%, catarrh in 37%. Pneumonia associated with COVID-19 was diagnosed in 23% of the children, and gastrointestinal symptoms in 31.3%. In 52% of the infants, elevated levels of D-dimers were observed, and in 40%, elevated levels of IL-6 serum concentration were observed. During the second wave of the pandemic, 6 times more infants were hospitalized, and the children were statistically significantly younger compared to the patients during the first wave (3 months vs 8 months, p < 0.0001 respectively). During the second wave, the infants were hospitalized for longer. COVID-19 in infants usually manifests as a mild gastrointestinal or respiratory infection, but pneumonia is also observed with falls in oxygen saturation, requiring oxygen therapy. Gastrointestinal symptoms are common in infants infected with SARS-CoV-2, and infant appetite disorders may lead to hospitalization. The clinical course of the disease differed significantly between the first and second wave of the pandemic. It seems that infants may play a role in the transmission of SARS-COV-2 infections in households, despite mild or asymptomatic courses; eating disorders in infants should be an indication for COVID-19 testing.

Amyloid and Tau Protein Concentrations in Children with Meningitis and Encephalitis.

Alzheimer's disease (AD) has emerged as a growing threat to human health. It is a multifactorial disorder, in which abnormal amyloid beta metabolism and neuroinflammation have been demonstrated to play a key role. Intrathecal inflammation can be triggered by infections and precede brain damage for years. We analyzed the influence of infections of the central nervous system on biomarkers that are crucially involved in AD pathology. Analyses of the cerebrospinal fluid (CSF) levels of Aß1-42, Aß1-40, Tau, and pTau proteins were performed in 53 children with neuroinfections of viral (n = 26) and bacterial origin (n = 19), and in controls (n = 8). We found no changes in CSF amyloid Aß1-42 concentrations, regardless of etiology. We showed an increase in tau and phosphorylated tau concentrations in purulent CNS infections of the brain, compared to other etiologies. Moreover, the total concentrations of tau in the CSF correlated with the CSF absolute number of neutrophils. These findings and the Aß 42/40 concentration quotient discrepancies in CFS between meningitis and encephalitis suggest that infections may affect the metabolism of AD biomarkers.

The Lack of the Association of the CCR5 Genotype with the Clinical Presentation and Frequency of Tick-Borne Encephalitis in the Polish Population.

BACKGROUND: The host factors influencing the susceptibility to and the severity of tick-borne encephalitis (TBE) are poorly defined. The loss-of-function Δ32 mutation in the chemokine receptor gene CCR5 was identified as a risk factor for West Nile encephalitis and possibly for TBE, suggesting a protective role of CCR5 in Flavivirus encephalitis. METHODS: We studied the CCR5 genotype in 205 TBE patients stratified by a clinical presentation and 257 controls from the same endemic area (Podlasie, Poland). The genotype distribution between the groups and differences between TBE patients with different genotypes were analyzed. RESULTS: There were 36 (17.6%) CCR5Δ32 heterozygotes and 3 (1.5%) homozygotes in the TBE group, with no statistically significant difference in comparison with the controls. The CCR5Δ32 allele did not associate with the clinical presentation or the severity of TBE. The cerebrospinal fluid (CSF) inflammatory parameters did not differ between the wild-type (wt/wt) and wt/Δ32 genotype patients. The TBE clinical presentation and CSF parameters in three Δ32/Δ32 homozygotes were unremarkable. CONCLUSIONS: The lack of association of CCR5Δ32 with the risk and clinical presentation of TBE challenges the suspected CCR5 protective role. CCR5 is not indispensable for the effective immune response against the TBE virus.

The Role of Glucocorticoids in the Treatment of Multisystem Inflammatory Syndrome (MIS-C)-Data from POLISH MIS-C Registry.

BACKGROUND: Multisystem inflammatory syndrome (MIS-C) is a condition related to COVID-19. It's most significant feature is cardiac involvement. METHODS: We have analyzed data from 42 hospitals in the Polish MIS-C Registry. To compare the effect of GCS on fever, we formed two groups: the first treated with IVIG and the second treated with IVIG+GCS. RESULTS: There were 111 boys and 56 girls; the mean age was 8.57 years. All the patients were treated with IVIG: 76 patients with IVIG only, and 91 patients with IVIG+GCS. There were no statistically significant differences between the groups regarding age, gender, BMI, or inflammatory markers. Methylprednisolone was the most common drug (80%). Echocardiographic abnormalities on admission were more prevalent in the IVIG+GCS group. Mean time from IVIG infusion to subsidence of fever was 1.1 days, and 1.5 for those in the IVIG+GCS group. CONCLUSIONS: GCS are commonly used in the treatment of MIS-C patients in Poland. Various GCS regimens are used, from a single dose to a month-long therapy. Children with lower lymphocyte levels and cardiac abnormalities on an echocardiographic examination performed on admission were more likely to receive GCS+IVIG. The effect of GCS is difficult to access as patients were not randomly assigned to receive the treatment.

Pneumonia, gastrointestinal symptoms, comorbidities, and coinfections as factors related to a lengthier hospital stay in children with COVID-19-analysis of a paediatric part of Polish register SARSTer.

BACKGROUND: Although COVID-19 is associated with a mild course in children, a certain proportion requires admission to hospital due to SARS-CoV-2 infection and coexisting diseases. The prospective multicenter study aimed to analyze clinical factors influencing the length of the hospital stay (LoHS) in children with COVID-19. METHODS: The study included 1283 children from 14 paediatric infectious diseases departments with diagnosed SARS-CoV-2 infection. Children were assessed in respective centres regarding indications for admission to hospital and clinical condition. History data, clinical findings, laboratory parameters, treatment, and outcome, were collected in the paediatric SARSTer register. The group of children with a hospital stays longer than seven days was compared to the remaining patients. Parameters with a statistically significant difference were included in further logistic regression analysis. RESULTS: One thousand one hundred and ten children were admitted to the hospital, 763 children were hospitalized >24 h and 173 children >7 days. 268 children had comorbidities. Two hundred and eleven children had an additional diagnosis with coinfections present in 135 children (11%). Factors increasing the risk of higher LoHS included pneumonia [odds ratio-OR 3.028; 95% confidence interval-CI (1.878-4.884)], gastrointestinal symptoms [OR = 1.556; 95%CI (1.049-2.322)], or rash [OR = 2.318; 95%CI (1.216-4.418)] in initial clinical findings. Comorbidities [OR = 2.433; 95%CI (1.662-3.563)], an additional diagnosis [OR = 2.594; 95%CI (1.679-4.007)] and the necessity of the empirical antibiotic treatment [OR = 2.834; 95%CI (2.834-6.713)] were further factors related to higher LoHS. CONCLUSIONS: The clinical course of COVID-19 was mild to moderate in most children. Factors increasing the risk of higher LoHS included pneumonia, gastrointestinal symptoms, comorbidities, an additional diagnosis, and the empirical antibiotic treatment.

Clinical and Epidemiological Characteristics of 1283 Pediatric Patients with Coronavirus Disease 2019 during the First and Second Waves of the Pandemic-Results of the Pediatric Part of a Multicenter Polish Register SARSTer.

This prospective multicenter cohort study aimed to analyze the epidemiological and clinical characteristics of coronavirus disease 2019 (COVID-19) in children. The study, based on the pediatric part of the Polish SARSTer register, included 1283 children (0 to 18 years) who were diagnosed with COVID-19 between 1 March 2020 and 31 December 2020. Household contact was reported in 56% of cases, more frequently in younger children. Fever was the most common symptom (46%). The youngest children (0-5 years) more frequently presented with fever, rhinitis and diarrhea. Teenagers more often complained of headache, sore throat, anosmia/ageusia and weakness. One fifth of patients were reported to be asymptomatic. Pneumonia was diagnosed in 12% of patients, more frequently in younger children. During the second wave patients were younger than during the first wave (median age 53 vs. 102 months, p < 0.0001) and required longer hospitalization (p < 0.0001). Significantly fewer asymptomatic patients were noted and pneumonia as well as gastrointestinal symptoms were more common. The epidemiological characteristics of pediatric patients and the clinical presentation of COVID-19 are age-related. Younger children were more frequently infected by close relatives, more often suffered from pneumonia and gastrointestinal symptoms and required hospitalization. Clinical courses differed significantly during the first two waves of the pandemic.

Rotavirus gastroenteritis in children hospitalized in northeastern Poland in 2006-2020: Severity, seasonal trends, and impact of immunization.

OBJECTIVES: The introduction of the rotavirus vaccine in 2006 significantly reduced childhood incidence of acute gastroenteritis (AGE) worldwide. The rotavirus vaccine was included in Poland's national immunization program in 2021. Our study aimed to summarize the epidemiology of AGE in northeastern Poland prior to 2021 and to evaluate the effectiveness of voluntary, out-of-pocket rotavirus childhood vaccination on the incidence of rotavirus AGE. METHODS: A review of patients aged 0-17 years with gastroenteritis hospitalized between 2006 and 2020 in northeastern Poland in the context of rotavirus vaccine coverage in the region. RESULTS: Rotavirus was the most common agent of gastroenteritis in hospitalized patients. The seasonality of rotavirus gastroenteritis peaked between February and May in each year of study, except for 2020, when the COVID-19 pandemic skewed any viable comparison of seasonality. Rotavirus vaccine coverage in northeastern Poland did not exceed 25% during the study period and had no impact on hospitalization numbers. CONCLUSIONS: Rotavirus was the primary causative agent of AGE in children hospitalized in northeastern Poland during the study period. Voluntary vaccinations did not affect the number of hospitalizations due to rotavirus AGE. Our data suggest that universal immunization is key to achieving a significant reduction of rotavirus-associated diarrhea.

Cumulative Effects of Particulate Matter Pollution and Meteorological Variables on the Risk of Influenza-Like Illness.

The cold season is usually accompanied by an increased incidence of respiratory infections and increased air pollution from combustion sources. As we are facing growing numbers of COVID-19 cases caused by the novel SARS-CoV-2 coronavirus, an understanding of the impact of air pollutants and meteorological variables on the incidence of respiratory infections is crucial. The incidence of influenza-like illness (ILI) can be used as a close proxy for the circulation of influenza viruses. Recently, SARS-CoV-2 has also been detected in patients with ILI. Using distributed lag nonlinear models, we analyzed the association between ILI, meteorological variables and particulate matter concentration in Bialystok, Poland, from 2013-2019. We found an exponential relationship between cumulative PM2.5 pollution and the incidence of ILI, which remained significant after adjusting for air temperatures and a long-term trend. Pollution had the greatest effect during the same week, but the risk of ILI was increased for the four following weeks. The risk of ILI was also increased by low air temperatures, low absolute humidity, and high wind speed. Altogether, our results show that all measures implemented to decrease PM2.5 concentrations would be beneficial to reduce the transmission of SARS-CoV-2 and other respiratory infections.

Tick-borne encephalitis - a review of current epidemiology, clinical symptoms, management and prevention.

Tick-borne encephalitis virus (TBEV), which causes central nervous system infections, is a major health problem in Europe and Asia. This virus is transmitted mainly via the bite of a tick. However, an infection may also occur as a result of consuming raw milk. In 2018, a total of 3 092 cases of tick-borne encephalitis (TBE) were reported in EU countries. In recent years, TBE has emerged in previously unaffected regions; thus, new endemic areas have been identified. Most cases of TBE occur in spring and autumn, which correlates with increased tick activity. TBE is found in all age groups, including infants. The clinical presentation of TBE varies, but the severity of the infection and risk of complications increase with age. Post-encephalitic syndrome, which affects up to 50% of infected individuals, significantly reduces quality of life. Currently, there is no effective treatment for TBE, and supportive management is used in the acute phase of the disease. Therefore, anti-TBE immunization and the avoidance of tick bites are of key importance in preventing this infection.