Incidence, Risk, and Severity of SARS-CoV-2 Reinfections in Children and Adolescents Between March 2020 and July 2022 in Serbia.

Importance: During the COVID-19 pandemic, children and adolescents were massively infected worldwide. In 2022, reinfections became a main feature of the endemic phase of SARS-CoV-2, so it is important to understand the epidemiology and clinical impact of reinfections. Objective: To assess the incidence, risk, and severity of pediatric SARS-CoV-2 reinfection. Design, Setting, and Participants: This retrospective cohort study used epidemiologic data of documented SARS-CoV-2 infections from the surveillance database of the Institute for Public Health of Vojvodina. A total of 32 524 children and adolescents from Vojvodina, Serbia, with laboratory-confirmed SARS-CoV-2 infection between March 6, 2020, and April 30, 2022, were followed up for reinfection until July 31, 2022. Main Outcomes and Measures: Incidence rates of documented SARS-CoV-2 reinfection per 1000 person-months, estimated risk of documented reinfection 90 days or more after laboratory confirmation of primary infection, reinfection severity, hospitalizations, and deaths. Results: The study cohort included 32 524 children and adolescents with COVID-19 (mean [SD] age, 11.2 [4.9] years; 15 953 [49.1%] male), including 964 children (3.0%) who experienced documented reinfection. The incidence rate of documented reinfections was 3.2 (95% CI, 3.0-3.4) cases per 1000 person-months and was highest in adolescents aged 12 to 17 years (3.4; 95% CI, 3.2-3.7). Most reinfections (905 [93.9%]) were recorded in 2022. The cumulative reinfection risk was 1.3% at 6 months, 1.9% at 9 months, 4.0% at 12 months, 6.7% at 15 months, 7.2% at 18 months, and 7.9% after 21 months. Pediatric COVID-19 cases were generally mild. The proportion of severe clinical forms decreased from 14 (1.4%) in initial episodes to 3 (0.3%) in reinfections. Reinfected children were approximately 5 times less likely to have severe disease during reinfection compared with initial infection (McNemar odds ratio, 0.2; 95% CI, 0.0-0.8). Pediatric reinfections rarely led to hospitalization (0.5% vs 1.3% during primary infections), and none resulted in death. Conclusions and Relevance: This cohort study found that the SARS-CoV-2 reinfection risk remained substantially lower for children and adolescents compared with adults as of July 2022. Pediatric infections were mild, and reinfections were even milder than primary infections.

Risk and severity of SARS-CoV-2 reinfections during 2020-2022 in Vojvodina, Serbia: A population-level observational study.

Background: Data on the rate and severity of SARS-CoV-2 reinfections in real-world settings are scarce and the effects of vaccine boosters on reinfection risk are unknown. Methods: In a population-level observational study, registered SARS-CoV-2 laboratory-confirmed Vojvodina residents, between March 6, 2020 and October 31, 2021, were followed for reinfection ≥90 days after primary infection. Data were censored at the end of follow-up (January 31, 2022) or death. The reinfection risk was visualized with Kaplan-Meier plots. To examine the protective effect of vaccination, the subset of individuals with primary infection in 2020 (March 6-December 31) were matched (1:2) with controls without reinfection. Findings: Until January 31, 2022, 13,792 reinfections were recorded among 251,104 COVID-19 primary infections (5.49%). Most reinfections (86.77%, 11,967/13,792) were recorded in January 2022. Reinfections were mostly mild (99.17%, 13,678/13,792). Hospitalizations were uncommon [1.08% (149/13,792) vs. 3.66% (505/13,792) in primary infection] and COVID-19 deaths were very rare (20/13,792, case fatality rate 0.15%). The overall incidence rate of reinfections was 5.99 (95% CI 5.89-6.09) per 1000 person-months. The reinfection risk was estimated as 0.76% at six months, 1.36% at nine months, 4.96% at 12 months, 16.68% at 15 months, and 18.86% at 18 months. Unvaccinated (OR=1.23; 95%CI=1.14-1.33), incompletely (OR=1.33; 95%CI=1.08-1.64) or completely vaccinated (OR=1.50; 95%CI=1.37-1.63), were modestly more likely to be reinfected compared with recipients of a third (booster) vaccine dose. Interpretation: SARS-CoV-2 reinfections were uncommon until the end of 2021 but became common with the advent of Omicron. Very few reinfections were severe. Boosters may modestly reduce reinfection risk. Funding: No specific funding was obtained for this study.

Prevalence and Associated Factors of Physical Activity among Medical Students from the Western Balkans.

The student population includes young adults who need nutrition and regular physical activity (PA) for mental, cognitive, and physical development. It is estimated that, globally, only 25-40% of the university student population is involved in regular PA. To date, no research has been conducted in the Western Balkans to address the PA of medical students. The aim of this study was to investigate the prevalence and factors influencing PA among medical students from the Western Balkans. A cross-sectional study included 2452 students from 14 medical faculties in five countries (Slovenia, Croatia, Bosnia and Herzegovina, North Macedonia and Serbia). There were significantly more students who engaged than those who did not engage in some type of regular (daily) PA. Gender, overweight or obesity, and household income are significantly associated with students' PA. Students who are more often involved in regular daily PA and have higher daily PA levels are more likely to be males whose household income is above average. In order to improve the health of the student population, the public health authorities need to continuously investigate the PA of students and introduce appropriate activities to increase their level of PA.

Impact of the COVID-19 Pandemic on Cardiology Emergency Department Visits.

In 2020, decreased emergency department (ED) visits and hospitalization rates during the COVID-19 outbreak were reported. There is no data about cardiovascular emergencies and mortality for the whole COVID-19 year.This study aimed to compare the rates of cardiology ED visits, hospital admissions, and intrahospital mortality between the pre-COVID-19 and COVID-19 years in a single high-volume center.The retrospective observational cross-sectional study analyzed data on the number of ED visits, hospital admissions by different cardiovascular diagnoses, and outcomes.A total of 11744 patients visited the cardiology ED in the pre-COVID-19 year compared with 9145 in the COVID-19 year, indicating an overall decrease of 22.1% (P = 0.02) (IR 78.76 versus 61.33; incidence rate ratios (IRR) 1.28, P = 0.00), with an observed decrease of 25.5% in the number of hospitalizations (33.1% versus 31.6%, P = 0.02). A marked decrease in hospitalizations for cardiovascular emergencies was observed for hypertensive heart disease (-72.8%, P < 0.0001), acute coronary syndrome (-17.8%, P < 0.0001), myocardial and pericardial diseases and endocarditis (-61.2%, P = 0.00), and valvular heart disease (-70.8%, P < 0.0001). In the COVID-19 year, patients had increased need for mechanical ventilatory support (7% versus 6.3%, P = 0.03) with no overall difference in intrahospital mortality (IR 2.71 versus 2.78, IRR 0.98, 95% CI 0.82-1.16, P = 0.39).Decreased ED visits and hospitalizations not just in outbreaks but through the whole COVID-19 year highlight the risk of continuous delay of needed care for emergency life-threatening cardiovascular diseases. Urgent comprehensive strategies that will address patient- and system-related factors to decrease morbidity and mortality and prevent collateral damage of the pandemic are needed.

Cigarette Smoking among Medical Students from the Western Balkan.

University student's smoking is a significant public health problem. It is estimated that, globally, every fifth medical student is a smoker. So far, no research dealing with cigarette smoking among medical students has been conducted in the countries of the Western Balkans. The aim of this study was to examine the prevalence and risk factors of cigarette smoking among Western Balkans medical students. A cross-sectional study was conducted among 2452 students from 14 medical faculties in the Western Balkans (Republic of Slovenia, Republic of Croatia, Bosnia and Herzegovina, Republic of North Macedonia and Republic of Serbia). The data were gathered through an online survey. There were significantly more non-smokers than smokers among medical students. Only gender and parents smoking status were statistically significantly associated with students smoking status. The smokers were more often male students, who lived in urban areas prior their studies, and whose parents were both smokers. With the aim of monitoring and enhancing student population health, it is necessary for public health activists and health officials to continually survey the students' smoking status in order to recognize the smoking influencing factors, and form and take on appropriate activities to improve the prevention of cigarette smoking among students, as well as motivate those who smoke to give up smoking, which would contribute to improving the health of the student population.

N-Terminal Prohormone of Brain Natriuretic Peptide (NT-proBNP) as a Diagnostic Biomarker of Left Ventricular Systolic Dysfunction in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease (AECOPD).

INTRODUCTION: Left ventricular systolic dysfunction (LVSD) and cardiac decompensation often accompany AECOPD. Differentiation between the two is difficult and mainly relies on clinical and echocardiographic diagnostic procedures. The value of biomarkers, such as NT-proBNP, as diagnostic tools is still insufficiently investigated. The main goals of this trial were to investigate the value of NT-proBNP as a diagnostic tool for LVSD in AECOPD patients and determine its cut-off value which could reliably diagnose LVSD during AECOPD. PATIENTS AND METHODS: This trial prospectively enrolled 209 patients with AECOPD. The patients were divided into four groups-AECOPD plus chronic pulmonary heart disease (CPHD) with or without left ventricular compromise (LVSD), and AECOPD patients without CPHD with or without LVSD. NT-proBNP was measured within first 48 h of hospitalization. RESULTS: Majority of patients were male (61%) active smokers (41.6%), average age of 68 years. High quality of echocardiography was obtained in 63.3 and 22.5% of the patients had LVSD. Average value of NT-proBNP in patients with LVSD was 3303.2 vs. 1092.5 pg/mL in patients without LVSD. Significant differences in NT-proBNP value (p = 0.0001) were determined between observed patient groups. At the cut-off value of 1505 pg/mL, sensitivity, specificity, and positive and negative predictive values are 76.6, 83.3, 57.1, and 92.47%, respectively. CONCLUSION: At the cut-off value of 1505 pg/mL NT-proBNP could be used as a diagnostic marker for LVSD in acute exacerbation of COPD.

Varicella zoster virus transmission dynamics in Vojvodina, Serbia.

This study aimed at establishing baseline key epidemiological parameters for varicella zoster virus (VZV) infection in Vojvodina, Serbia, with the ultimate goal to quantify the VZV transmission potential in the population. Seroprevalence data generated during the first large cross-sectional VZV serosurvey were modelled, using a two-tiered modelling approach to calculate age-specific forces of infection (FOI), the basic reproduction number (R0) and herd immunity threshold (H). Seroprevalence and modelling data were compared with corresponding pre-vaccination epidemiological parameters from 11 countries participating in the European Sero-Epidemiology Network 2 (ESEN2) project. Serbia fits into the general dynamic VZV transmission patterns in Europe in the pre-vaccine era, with estimated R0 = 4.12, (95% CI: 2.69-7.07) and H = 0.76 (95% CI: 0.63-0.86). The highest VZV transmission occurs among preschool children, as evidenced by the estimation of the highest FOI (0.22, 95% CI: 0.11-0.34) in the 0.5-4 age group, with a peak FOI of 0.25 at 2.23 years. Seroprevalence was consistently lower in 5-14 year-olds, resulting in considerable shares of VZV-susceptible adolescents (7.3%), and young adults (6%), resembling the situation in a minority of European countries. The obtained key epidemiological parameters showed most intense VZV transmission in preschool children aged <4 years, justifying the consideration of universal childhood immunization in the future. National immunization strategy should consider programs for VZV serologic screening and immunization of susceptible groups, including adolescents and women of reproductive age. This work is an important milestone towards the evaluation of varicella immunization policy options in Serbia.

Early pregnancy angiogenic proteins levels and pregnancy related hypertensive disorders.

INTRODUCTION: Normal placental vascular development depends on multiple interactions of many regulatory molecules including pro and antiangiogenic proteins. It is considered that these vascular modulators might be one of the factors responsible for development hypertensive disorders in pregnancy. OBJECTIVE: To evaluate and compare the early pregnancy (11-14 week of gestation) serum level of angiogenic proteins sFlt1, VEGF i PIGF between different types of pregnancy related hypertensive disorders. MATERIALS AND METHODS: The study included 177 pregnant women between 11 and 14 weeks of gestation, divided into four study subgroups (preeclampsia group-41, gestational hypertension group-31, chronic hypertension group-32 and miscarriage group-19) and control group-54. Blood samples (serum) were taken for measuring sFlt1, VEGF i PIGF by a quantitative ELISA technique and measuring other biochemical and hematological parameters. RESULTS: Significantly higher levels of sFlt1 were in the subgroups with preeclampsia and miscarriages, significantly lower level of VEGF in the all study subgroups and lover level of PIGF were in miscarriage group. In the groups with chronic and gestational hypertension there were higher level of sFlt1 and lover level of VEGF than in the control group, but the differences did not reach statistical significance. CONCLUSION: Early pregnancy imbalance between antiangiogenic protein sFlt1 and proangiogenic molecules VEGF and PIGF could have impact on pathophysiology of placental disorders which leads to development of pregnancy related hypertensive disorders.

Clinical significance of determining plasma homocysteine: case-control study on arterial and venous thrombotic patients.

AIM: To determine the differences in plasma homocysteine levels between three MTHFR 677 genotype subgroups in patients with thrombosis and in controls, as well as between patients with thrombosis and controls with the same MTHFR 677 genotype. METHODS: This case-control study was conducted in Clinical Center of Vojvodina, Novi Sad, from June to December 2011. We included 65 patients with either arterial or venous thrombosis (mean age, 40.97 ± 11.38 years) and 65 controls with no history or clinical evidence of any thrombotic event (mean age, 41.23 ± 11.12 years). Patients and controls were age- and sex-matched. RESULTS: In comparison with controls, thrombotic patients had significantly higher homocysteine levels (12.81 ± 4.94 µmol/L vs 9.82 ± 3.68 µmol/L; P<0.001) and significantly higher incidence of hyperhomocysteinemia (55% vs 22%; P<0.001; odds ratio [OR]=4.521). There were no significant differences in homocysteine levels between homozygous carriers, heterozygous carriers, and non-carriers of the MTHFR 677 mutation in either thrombotic patients (12.97 ± 5.40 µmol/L vs 12.55 ± 5.71 µmol/L vs 13.27 ± 1.71 µmol/L; P=0.100) or controls (10.07±2.50 µmol/L vs 10.25 ± 4.84 µmol/L vs 9.20 ± 2.44 µmol/L; P=0.651). However, in comparison with controls, homozygous carriers in thrombotic patient group did not have significantly higher levels of homocysteine (12.97 ± 5.40 µmol/L vs 10.07 ± 2.50 µmol/L; P=0.072), but heterozygous carriers (12.55 ± 5.71 µmol/L vs 10.25 ± 4.84 µmol/L; P=0.020) and non-carriers (13.27 ± 1.71 µmol/L vs 9.20 ± 2.44 µmol/L; P<0.001) did. There was no significant difference in homocysteine levels between patients with arterial and venous thrombosis (12.76 ± 3.60 µmol/L vs 12.86 ± 5.51 µmol/L; P=0.990) and between patients with one thrombotic event and those with recurrent thrombotic events (12.14 ± 3.20 µmol/L vs 15.25 ± 8.51 µmol/L; P=0.254). CONCLUSION: Plasma homocysteine levels have a greater clinical significance in the prevention of thrombosis and managing its complications than MTHFR 677 genotyping.

Heart rate recovery after submaximal exercise in four different recovery protocols in male athletes and non-athletes.

The effects of different recovery protocols on heart rate recovery (HRR) trend through fitted heart rate (HR) decay curves were assessed. Twenty one trained male athletes and 19 sedentary male students performed a submaximal cycle exercise test on four occasions followed by 5 min: 1) inactive recovery in the upright seated position, 2) active (cycling) recovery in the upright seated position, 3) supine position, and 4) supine position with elevated legs. The HRR was assessed as the difference between the peak exercise HR and the HR recorded following 60 seconds of recovery (HRR60). Additionally the time constant decay was obtained by fitting the 5 minute post-exercise HRR into a first-order exponential curve. Within- subject differences of HRR60 for all recovery protocols in both groups were significant (p < 0. 001) except for the two supine positions (p > 0.05). Values of HRR60 were larger in the group of athletes for all conditions (p < 0.001). The time constant of HR decay showed within-subject differences for all recovery conditions in both groups (p < 0.01) except for the two supine positions (p > 0.05). Between group difference was found for active recovery in the seated position and the supine position with elevated legs (p < 0.05). We conclude that the supine position with or without elevated legs accelerated HRR compared with the two seated positions. Active recovery in the seated upright position was associated with slower HRR compared with inactive recovery in the same position. The HRR in athletes was accelerated in the supine position with elevated legs and with active recovery in the seated position compared with non-athletes. Key pointsIn order to return to a pre-exercise value following exercise, heart rate (HR) is mediated by changes in the autonomic nervous system but the underlying mechanisms governing these changes are not well understood.Even though HRR is slower with active recovery, lactate elimination after high intensity exercise might be more important for athletes than the de-cline of heart rate.Lying supine during recovery after exercise may be an effective means of transiently restoring HR and vagal modulation and a safe position for prevention of syncope.