Prevalence of Carcinogenic Genotypes of HPV-Infected Women in a Ten-Year Period (2014-2023) in Vojvodina, Serbia.

Background and Objectives: Human papillomavirus (HPV) infection and its etiological role in the development of cervical cancer are well established. The cervical cancer mortality rate in Serbia is one of the highest among European countries, and this cancer is the second-leading cause of death in Serbian women aged from 15 to 44. Materials and Methods: This retrospective study was conducted at the Institute of Public Health of Vojvodina. A total of 10,062 cervical specimens from Serbian women were collected and HPV tested in ten years. The study patients were divided into five age groups. HPV genotype testing was performed using a commercial kit to detect 14 high-risk (HR) HPV genotypes. Additionally, cervix cytology data have been available for patients tested in 2022 and 2023. Results: An overall positive rate was found in 43.3% of patients (4356/10,062). A single HPV infection (62.1%) was the main infection pattern. The most frequent HR HPV genotypes were HPV 16, 31, 52, 56, 39, and 51, comprising 62.3% of the detected genotypes, including multiple infections. A significant difference was noted in the HPV prevalence across the different age groups, with a bimodal distribution of HPV infection. The highest prevalence was recorded in the age group ≤ 30 and those after 61 years. Women diagnosed with high-grade squamous intraepithelial lesions (HSIL) were significantly older compared to others. HR HPV is the most prevalent in patients with HSIL cytological findings (76.5%). The most common type, according to age-specific distribution and cytological findings, was HR HPV 16. Conclusions: This study provides comprehensive data on HR HPV distribution among Serbian women, which can serve as a basis for subsequent monitoring of genotypic distribution. It is particularly significant considering they are missing in the updated ICO/IARC Report for Serbia, and the cervical cancer mortality rate in Serbia is one of the highest among European countries.

Pertussis Epidemiology in the Autonomous Province of Vojvodina, Serbia, 1948-2023.

Pertussis continues to be a significant public health concern. We aimed to examine the epidemiological characteristics of pertussis in Vojvodina, which accounts for almost a third of Serbia's population. Our aim was to determine the overall and age-specific incidence and mortality rates of pertussis in Vojvodina from 1948 to 2023, as well as the coverage of immunization against pertussis from 1960 to 2023. In the period 1948-2023, 42,259 cases of pertussis were reported. Following the introduction of the DTwP vaccine (1960) in Serbia, the reported incidence of pertussis began to decline. In 2001, for the first time since introduction of pertussis surveillance in Vojvodina, no pertussis cases were reported. Since 2012, the reported incidence of pertussis has once again increased, and peaked (41.1/100,000) in 2023, approaching the incidence rates recorded shortly after the introduction of DTwP vaccine. A shift in the age profile of pertussis from children aged 0-6 years to school-aged children (7-14 years) occurred between 2012 and 2023, when 48.3% of pertussis cases occurred in this age group. Although the incidence rates of pertussis among individuals aged 20 years and older were significantly lower than among younger age groups, there is evidence of an increasing trend in pertussis cases, particularly among those aged 40-49 years, since 2012. Based on the findings of this study, it is imperative to introduce additional booster doses of the aP vaccine for individuals aged 14 years, along with implementing maternal immunization strategies targeting women of childbearing age.

Nutritional Status and Quality of Life in Patients with Oral Squamous Cell Carcinoma Before and After Surgical Oncological Treatment: A Single-Center Retrospective Study.

BACKGROUND Oral squamous cell carcinoma (OSCC) is the most common of head and neck malignancies in well-developed countries. In most cases, patients with OSCC experience a degree of nutritional status disturbances and decreased quality of life (QoL). This study aimed to compare nutritional status and QoL in 51 patients before and after surgery for OSCC. MATERIAL AND METHODS Fifty-one eligible patients with OSCC were followed during a 3-year period (2019-2022). For all patients, we determined body mass index (BMI), serum albumin (ALB), prognostic nutritional index, and nutritional risk index before and after treatment. Also, all patients completed a standardized QoL questionnaire before and after treatment. The obtained data were compared between the groups by using the t test and multivariate Cox regression. RESULTS The values of BMI and NRI were statistically significantly different between the preoperative and postoperative measurements (24.1 kg/m² vs 21.1 kg/m², and 103 vs 100.1, respectively, P=0.001), while values of ALB and prognostic nutritional index did not differ significantly (41.35 g/L vs 39.1 g/L, and 48.5 vs 46.2, respectively). Dysphagia (P=0.03) and chewing problems (P=0.04) were found to be the 2 most important factors decreasing the QoL of patients. CONCLUSIONS Based on our results, BMI and NRI were the most sensitive parameters of nutritional status. Dysphagia and chewing problems were the 2 most important factors affecting the QoL in patients with OSCC.

Seroprevalence Study of Anti-HBs Antibodies in the General Population of Vojvodina, Serbia.

Background and Objectives: Hepatitis B (HB) is a major global health problem and a potentially life-threatening disease caused by the hepatitis B virus (HBV). Also, it is an important cause of morbidity and mortality worldwide. Thanks to serological surveys, testing hepatitis B surface antibodies (anti-HBs) allows for serological assessments of their prevalence. The presence of anti-HBs, which protects against HBV infection, can be attributed to HB vaccination or natural HBV infection. The aim of our study was to evaluate the prevalence of HB surface antibodies (anti-HBs) as an indicator of collective immunity against HBV in the general population of the Autonomous Province of Vojvodina, Serbia. In addition, to distinguish whether anti-HBs were induced by the vaccine or by infection, the presence of antibodies against the hepatitis B core antigen (anti-HBc) was tested among those who were anti-HBs-positive. Materials and Methods: A total of 3467 residual sera samples, collected according to the specifications of the European Sero-Epidemiology Network 2 (ESEN2) study, from April 2015 to March 2016, were screened for the presence of anti-HBs using a chemiluminescence immunoassay. The difference between categorical variables was tested using the chi-square test. Results: Overall, 1870 (53.9%, 95% CI: 52.3-55.6) participants tested positive for anti-HBs. The median age of the study participants was 17 years (IQR 9-35). The anti-HB seroprevalence decreased with age, ranging from 80.7% (95% CI: 78.9-82.4) in the 1-19-year-old group to 16.4% (95% CI: 12.0-20.9) in the ≥60 years' age group. A total of 71 (3.8%, 95% CI: 2.9-4.7) serum samples were also anti-HBc-positive. Higher prevalence, but not statistically significant, was noticed in women (4.1%, 95% CI: 2.8-5.4) compared with men (3.5, 95% CI: 2.4-4.8) (p = 0.542). Also, there was a significant difference across the age groups, where those ≥60 years old had a prevalence of 65.9% (95% CI: 51.9-79.9) and the age category of 1-19-year-olds had just 0.2% (95% CI: 0.0-0.4) (p < 0.001). Conclusions: This study provides a comprehensive assessment of the anti-HBs seroprevalence of the general population in Vojvodina and provides an opportunity to better shape the national preventive strategy related to HBV.

Novel N-pyrocatechoyl and N-pyrogalloyl hydrazone antioxidants endowed with cytotoxic and antibacterial activity.

Over the years, pharmacological agents bearing antioxidant merits arose as beneficial in the prophylaxis and treatment of various health conditions. Hazardous effects of radical species hyperproduction disrupt normal cell functioning, thus increasing the possibility for the development of various oxidative stress-associated disorders, such as cancer. Contributing to the efforts for efficient antioxidant drug discovery, a thorough in vitro and in silico assessment of antioxidant properties of 14 newly synthesized N-pyrocatechoyl and N-pyrogalloyl hydrazones (N-PYRs) was accomplished. All compounds exhibited excellent antioxidant potency against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. The extensive in silico analysis revealed multiple favorable features of N-PYRs to inactivate harmful radical species, which supported the obtained in vitro results. Also, in silico experiments provided insights into the preferable antioxidant pathways. Prompted by these findings, the cytotoxicity effects and the influence on the redox status of cancer HCT-116 cells and healthy fibroblasts MRC-5 were evaluated. These investigations exposed four analogs exhibiting both cytotoxicity and selectivity toward cancer cells. Furthermore, the frequently uncovered antimicrobial potency of hydrazone-type hybrids encouraged investigations on G+ and G- bacterial strains, which revealed the antibacterial potency of several N-PYRs. These findings highlighted the N-PYRs as excellent antioxidant agents endowed with cytotoxic and antibacterial features.

Seroepidemiology of Human Parvovirus B19 Infection among the Population of Vojvodina, Serbia, over a 16-Year Period (2008-2023).

This study aimed to estimate the serological status and dynamic changes in the prevalence of Parvovirus B19 (PVB19) antibodies within the general population residing in the northern part of the Republic of Serbia (Province of Vojvodina) during a 16-year period. Serum samples were analyzed for Human PVB19-specific IgM and IgG antibodies using enzyme-linked immunosorbent assay (ELISA). Throughout the study period, the overall seroprevalence was 49.51%. Approximately 10% of patients exhibited a serologic profile positive for PVB19 IgM antibodies. Notably, seroprevalence varied significantly, ranging from 9.12% in the pediatric cohort (ages 1-4 years) to 65.50% in the adult demographic (40-59 years old). Seroprevalence was higher (51.88%) among women compared to men (42.50%). Immunologically naive pregnant women in the age groups 26-36 and 36-45 years had 45% (OR = 0.55, 95% CI: 0.31-1.00) and 52% (OR = 0.48; 95% CI: 0.24-0.94) lower odds of having negative IgM and IgG compared to those in age group 16-25 years old. Improved knowledge of the epidemiology of PVB19 may assist clinicians in the differential diagnosis of PVB19 clinical manifestations. The PVB19 detection is particularly important for monitoring individuals in risk groups such as women of reproductive age, medical staff, patients with hematological disorders, and those with immunodeficiency.

Oregano (Origanum vulgare) Essential Oil and Its Constituents Prevent Rat Kidney Tissue Injury and Inflammation Induced by a High Dose of L-Arginine.

This study aimed to evaluate the protective action of oregano (Origanum vulgare) essential oil and its monoterpene constituents (thymol and carvacrol) in L-arginine-induced kidney damage by studying inflammatory and tissue damage parameters. The determination of biochemical markers that reflect kidney function, i.e., serum levels of urea and creatinine, tissue levels of neutrophil-gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1), as well as a panel of oxidative-stress-related and inflammatory biomarkers, was performed. Furthermore, histopathological and immunohistochemical analyses of kidneys obtained from different experimental groups were conducted. Pre-treatment with the investigated compounds prevented an L-arginine-induced increase in serum and tissue kidney damage markers and, additionally, decreased the levels of inflammation-related parameters (TNF-α and nitric oxide concentrations and myeloperoxidase activity). Micromorphological kidney tissue changes correlate with the alterations observed in the biochemical parameters, as well as the expression of CD95 in tubule cells and CD68 in inflammatory infiltrate cells. The present results revealed that oregano essential oil, thymol, and carvacrol exert nephroprotective activity, which could be, to a great extent, associated with their anti-inflammatory, antiradical scavenging, and antiapoptotic action and, above all, due to their ability to lessen the disturbances arising from acute pancreatic damage. Further in-depth studies are needed in order to provide more detailed explanations of the observed activities.

Epidemiological Characteristics of COVID-19 during Seven Consecutive Epidemiological Waves (2020-2022) in the North Backa District, Serbia.

The COVID-19 pandemic continues to pose a threat to global public health. The purpose of this research was to determine the epidemiological characteristics of COVID-19 in the North Backa district while observing seven pandemic waves. The cross-sectional study was based on data from the COVID-19 surveillance database of the Institute for Public Health of Vojvodina during the period from March 2020 to December 2022. A total of 38,685 primary infections and 4067 reinfections caused by SARS-CoV-2 were notified. Pandemic waves caused by the Delta variant (cumulative incidence rate of 2482.37/100,000) and by the Omicron variant (cumulative incidence rate of 2994.45/100,000) emerged as significant focal points during the surveillance period. Over the course of three consecutive years (2020-2022), women were more affected (50.11%, 54.03%, and 55.68%, respectively). The highest incidence rates in age-specific categories were recorded in 2021 for the age group 40-49 (1345.32 per 10,000 inhabitants), while in 2022, they shifted towards the elderly population. Regarding vaccination status at the time of diagnosis, in 2021, around 15% of patients were vaccinated, while in 2022, the number increased to 37%. The most widely received vaccine was BBIBP-CorV (67.45%), followed by BNT162b2 (19.81%), Gam-COVID-Vac (9.31%), and ChAdOx1 nCoV-19 (3.42%) vaccine. The implementation of stringent public health measures and their mitigation, together with the emergence of new variants, influenced the dynamics of COVID-19 pandemic waves in the North Backa district. Notably, throughout the study period, the working-age population was the most affected, along with females, with a mild clinical presentation dominating. Reinfections were most frequently recorded during the latter pandemic waves. Dealing with this pandemic has provided some valuable lessons for the development of future strategies in the case of a similar public health crisis.

Motives and attitudes of parents toward HPV vaccination: Results from the initial period of HPV vaccine rollout in Serbia.

Human papillomavirus (HPV) infection is one of the most common viral infections in sexually active population worldwide, and is the main cause of cervical cancer, which is the fourth most common cancer among women. Serbia ranks third in incidence and mortality rate of cervical cancer in Europe. We conducted a cross-sectional study considering parents' motivation for the HPV vaccination of their children. Statistical analysis included descriptive statistics and a logistic regression model. We found that the strongest motive was "Recommendation from paediatrician" (20.2%), followed by the attitude that HPV vaccine protects against cancers in different localization (15.4%), the motive "It is better to vaccinate a child than expose them to potential risk of HPV infection" (13.3%) and "Feeling anxiety due to a possible infection and cancer in the child" (13.1%). For those parents that vaccinated their child for some other strongest motive, reasons like "Vaccine is free of charge", "Recommendation from friends and family" and motive "My child received all obligatory vaccines, so I want to receive this one as well", were significantly more frequently selected. In the group where paediatricians' recommendation was not a motive for accepting the HPV vaccine, the largest percentage of parents (89.6%) selected motive "HPV vaccine protects against cancers in different localization" and the motive "It is better to vaccinate a child than expose them to potential risk of HPV infection" (78.1%). Paediatrician's recommendation is very important for parents' decision to vaccinate, however, other motives also influenced and had significance in making the parents' decision to vaccinate their children against HPV. Encouraging trust in public health authorities in Serbia, highlighting the advantages of the HPV vaccine and further encouraging healthcare workers to give stronger recommendations can increase the HPV vaccine uptake. Finally, we provided the basis to create more targeted messages that will empower parents to vaccinate their children.

E6/E7 mRNA Expression of the Most Prevalent High-Risk HPV Genotypes in Cervical Samples from Serbian Women.

Cervical cancer caused by persistent infection with HR HPV genotypes is the second leading cause of death in women aged 15 to 44 in Serbia. The expression of the E6 and E7 HPV oncogenes is considered as a promising biomarker in diagnosing high-grade squamous intraepithelial lesions (HSIL). This study aimed to evaluate HPV mRNA and DNA tests, compare the results according to the severity of the lesions, and assess the predictive potential for the diagnosis of HSIL. Cervical specimens were obtained at the Department of Gynecology, Community Health Centre Novi Sad, Serbia, and the Oncology Institute of Vojvodina, Serbia, during 2017-2021. The 365 samples were collected using the ThinPrep Pap test. The cytology slides were evaluated according to the Bethesda 2014 System. Using a real-time PCR test, HPV DNA was detected and genotyped, while the RT-PCR proved the presence of E6 and E7 mRNA. The most common genotypes in Serbian women are HPV 16, 31, 33, and 51. Oncogenic activity was demonstrated in 67% of HPV-positive women. A comparison of the HPV DNA and mRNA tests to assess the progression of cervical intraepithelial lesions indicated that higher specificity (89.1%) and positive predictive value (69.8-78.7%) were expressed by the E6/E7 mRNA test, while higher sensitivity was recorded when using the HPV DNA test (67.6-88%). The results determine the higher probability of detecting HPV infection by 7% provided by the mRNA test. The detected E6/E7 mRNA HR HPVs have a predictive potential in assessing the diagnosis of HSIL. The oncogenic activity of HPV 16 and age were the risk factors with the strongest predictive values for the development of HSIL.

Epidemiological Transition and Strategies for the Control of Hepatitis A in Serbia.

BACKGROUND: Improvements in socioeconomic and hygienic conditions during the past decades led to declining hepatitis A (HA) seroprevalence in many countries. Aiming at informing HA vaccination policy, we assessed current epidemiological trends in Serbia by analyzing surveillance data for 2002-2021. METHODS: Data on cases and outbreaks were obtained from the Serbian national surveillance database and descriptively analyzed. HA incidence was calculated in relation to time, patients' residence, and demographics. RESULTS: Overall, 13,679 HA cases and 419 outbreaks were recorded with the highest incidence in the southeast. Downward HA trends were observed, while infant mortality was halved, and gross domestic product based on purchasing power parity (GDP PP) per capita, tripled. The average incidence dropped from 14.8 (95% CI 14.4-15.2)/100,000) in 2002-2006 to 1 (95% CI 0.9-1.1)/100,000)/100,000 in 2017-2021, while the number of outbreaks decreased (from 174 to 14). Sporadic cases and family clusters living in poor sanitary conditions occurred in recent years. The contact route of transmission was dominant (410/419, 97.9%). The highest average age-specific HA incidence shifted from 5-9 years in 2002-2006 to 10-19 years in 2017-2021.Serbia is transitioning towards very low HA endemicity. Enhanced surveillance and vaccination of high-risk groups are recommended as future public health priorities.

Distributions of Platelet-Derived Growth Factor Receptor-α Positive Cells and Interstitial Cells of Cajal in the Colon of Rats with Diabetes Mellitus Type 2.

Background and Objectives: Diabetic gastroenteropathy (DG) is a common complication of diabetes mellitus type 2. Interstitial cells are non-neural cells of mesenchymal origin inserted between nerve elements and smooth muscle cells, necessary for normal function and peristaltic contractions in the gastrointestinal (GI) tract. There are at least two types of interstitial cells within the GI muscle layer-interstitial cells of Cajal (ICC) and interstitial platelet-derived growth factor receptor α-positive cells (IPC). The mechanism of diabetic gastroenteropathy is unclear, and interstitial cells disorders caused by metabolic changes in diabetes mellitus (DM) could explain the symptoms of DG (slow intestinal transit, constipation, fecal incontinence). The aim of this study was to identify PDGFRα and c-kit immunoreactive cells in the colon of rats with streptozotocin-nicotinamide-induced diabetes mellitus type 2, as well as to determine their distribution in relation to smooth muscle cells and enteric nerve structures. Materials and Methods: Male Wistar rats were used, and diabetes type 2 was induced by an intraperitoneal injection of streptozotocin, immediately after intraperitoneal application of nicotinamide. The colon specimens were exposed to PDGFRα and anti-c-kit antibodies to investigate interstitial cells; enteric neurons and smooth muscle cells were immunohistochemically labeled with NF-M and desmin antibodies. Results: Significant loss of the intramuscular ICC, myenteric ICC, and loss of their connection in intramuscular linear arrays and around the ganglion of the myenteric plexus were observed with no changes in nerve fiber distribution in the colon of rats with diabetes mellitus type 2. IPC were rarely present within the colon muscle layer with densely distributed PDGFRα+ cells in the colon mucosa and submucosa of both experimental groups. In summary, a decrease in intramuscular ICC, discontinuities and breakdown of contacts between myenteric ICC without changes in IPC and nerve fibers distribution were observed in the colon of streptozotocin/nicotinamide-induced diabetes type 2 rats.

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.

Pyrazolone-type compounds (part II): in vitro and in silico evaluation of antioxidant potential; structure-activity relationship.

The pyrazolone class comprises a variety of hybrid compounds displaying diverse biological actions. Although studied for decades, these compounds are still of interest due to their facile chemical transformations. In our previous work, we presented the synthetic route of functionalised pyrazolone derivatives. The presence of pyrazolone structural motif in many drugs, such as edaravone, prompted us to investigate the antioxidant features of the selected compounds. In this paper, we provide an extensive in vitro and in silico description of the antioxidant properties of selected pyrazolone analogues. The obtained in vitro results revealed their great antiradical potency against the DPPH radical (IC50 values in the 2.6-7.8 µM range), where the best results were obtained for analogues bearing a catechol moiety. Density functional theory (DFT) was used to assess their antioxidant capacity from the thermodynamic aspect. Here, good agreement with in vitro results was achieved. DFT was employed for the prediction of the most preferable radical scavenging pathway, also. In polar solvents, the SPLET mechanism is a favourable scavenging route, whereas in nonpolar solvents the HAT is slightly predominant. Furthermore, antioxidant mechanisms were studied in the presence of relevant reactive oxygen species. The obtained values of the reaction enthalpies with the selected radicals revealed that HAT is slightly prevailing in polar solvents, while the SPLET mechanism is dominant in nonpolar solvents. Regarding the well-known antioxidant features of the drug edaravone, these findings represent valuable data for this pyrazolone class and could be used as the basis for further investigations.

Seroepidemiology of SARS-CoV-2 Virus in Healthcare Workers before Circulation of the Omicron Sublineages BA.4/BA.5 in Vojvodina, Serbia.

Healthcare workers (HCWs) are a vulnerable and critical population in the ongoing response to the SARS-CoV-2 pandemic. We aimed to estimate the seroprevalence in HCWs considering all of their previous contacts with the SARS-CoV-2 virus and/or the immunity acquired through their immunization against COVID-19 before the advent of the Omicron variants BA.4/BA.5. Serum samples were collected from 28 March to 10 June 2022. We covered 25% out of all the people who worked in some of the government healthcare centers (primary, secondary, and tertiary level) across the entire Autonomous Province of Vojvodina (Northern Serbia). Two serological tests (Anti-SARS-CoV-2 QuantiVac ELISA and LIAISON® SARS-CoV-2 TrimericS) were used to detect anti-spike IgG antibodies. The overall prevalence of the SARS-CoV-2 antibody among the 6936 HCWs was 92.96% [95% CI 92.33−93.55]. Regarding the type of serological test, there was a statistically significant (p = 0.0079) difference of the seropositivity obtained by the LIAISON® SARS-CoV-2 TrimericS (93.87%, 95% CI 92.97−94.69) and Anti-SARS-CoV-2 QuantiVac ELISA (92.23%, 95% CI 91.34−93.06) tests. Seropositivity to SARS-CoV-2 significantly (p < 0.0001) increased with the number of SARS-CoV-2 infections combined with the number of doses of the SARS-CoV-2 vaccines received. A vast majority of the HCWs in Vojvodina had detectable levels of antibodies to the spike protein of SARS-CoV-2, but despite this high seropositivity, it is unknown whether this herd immunity among HCWs is protective against the new variants of concern. Further research should evaluate the rates of reinfections and the associated severity of COVID-19 caused by the Omicron sublineages and/or new variants of SARS-CoV-2 among HCWs.

COVID-19 Breakthrough Infections among Patients Aged ≥65 Years in Serbia: Morbidity and Mortality Overview.

BACKGROUND: Vaccines against severe acute respiratory syndrome coronavirus 2 have shown effectiveness in the prevention of COVID-19. Breakthrough infections occur, and age has been shown to be one of the dominant risk factors for poorer outcome. This research focuses on characteristics of breakthrough infections in older adults. METHODS: This retrospective study was conducted for four months (March−June 2021) in the autonomous province of Vojvodina in Serbia on 11,372 patients using reverse-transcription polymerase chain reaction or antigen-detection rapid diagnostic tests verifying COVID-19 in those aged ≥65 years. Demographics, comorbidities, disease severity, and final outcomes were evaluated in fully vaccinated compared to unvaccinated individuals. Individuals were divided into younger-old (65−74 years) and older-old (≥75 years) age groups and differences between those groups were further evaluated. Binary logistic regression was performed to identify independent predictors of poor outcome. RESULTS: By the end of the research, 51.3% of the population of APV 65−74 years, as well as 46.2% of those older than 74 years, were vaccinated. From the acquired sample, 17.4% had breakthrough infection. Asymptomatic forms were higher in both age groups of vaccinated vs. unvaccinated (3.9%­younger-old, 6.3%­older-old vs. 2.9%­younger-old, 3.9%­older-old). The same results were registered with mild symptoms (82.1%­younger-old, 68.1%­older-old vs. 76.3%­younger-old, 57.5%­older-old) (p < 0.001). The case fatality ratio of the vaccinated population was smaller than the unvaccinated population in both groups (3.1% vs. 7.9%­younger-old; 11.4% vs. 22.5%­older-old) (p < 0.001). The odds ratio for poor outcome in unvaccinated individuals was 2.3 (95% confidence interval, p < 0.001) for the total sample. CONCLUSIONS: An increase in asymptomatic and mild forms, as well as decrease in severe or critical forms and poor outcomes, were noted in the vaccinated population. Choosing to avoid vaccination against SARS-CoV-2 may increase the chance of poor outcome in older individuals.

Pneumococcal carriage in adults aged 50 years and older in outpatient health care facility during pandemic COVID-19 in Novi Sad, Serbia.

BACKGROUND: Data related to carriage of Streptococcus pneumoniae (Spn) and antimicrobial resistance patterns in middle-aged and older adults are limited. We assessed the carriage of Spn, and its antibiotic resistance patterns, among participants ≥50 years of age living in the city of Novi Sad during the second year of COVID-19 pandemic. METHODS: Analysis of prospectively collected data among participants with or without symptoms of upper respiratory tract infection who visited their elected physicians in the Primary Health Care Centre of Novi Sad (outpatient facility) was conducted from May 18, 2021 to December 7, 2021. Both nasopharyngeal (NP) and oropharyngeal (OP) samples from each participant were collected. RESULTS: A total of 1042 samples from 521 study subjects (1 NP and 1 OP sample from each person) were collected. Sixteen samples from the same number of persons (3.1%, 95% confidence interval: 1.76%-4.94%) were culture positive for the presence of Spn. Overall, the median age of study participants was 71 years (range, 50-93 years; 90th percentile, 77 years), and most (197/521, 37.8%) of them were 70-79 years of age. A majority of the study subjects were: females (324/521; 62.2%), sampled during May and June 2021 (376/521, 72.2%), those who did not have contact with children aged 0-10 years in the family (403/521; 77.4%), without smokers in the household (443/521; 85.0%), and those who did not receive vaccine against Spn (519/521; 99.6%). Out of 16 Spn positive samples, for six participants, Spn carriage serotypes were obtained and there were four vaccine (6A, 11A, 15B, and 18C) serotypes, and two (6C and 35F) non-vaccine serotypes. Remaining 10 (62.50%) samples were non-typeable isolates of pneumococci. Among four vaccine serotypes, two (6A and 18C) were represented in PCV13, and 18C along with the other two (11A and 15B) in PPSV23 vaccine. The highest level of resistance of Spn isolates was observed for erythromycin, (10 or 62.50%), and tetracycline, (7 or 43.75%), one isolate showed resistance to penicillin, ampicillin, and amoxicillin/amoxicillin-clavulanic acid, while none of them were resistant to ceftriaxone, trimethoprim/sulfamethoxazole and levofloxacin. There were three multi-drug resistant isolates; one was identified as 6C (non-vaccine serotype), and two other were non-typeable isolates of Spn. CONCLUSIONS: In this first study conducted in Serbia on Spn carriage in adults ≥50 years of age, we found low prevalence of Spn carriage and identified 6 serotypes of Spn, four of which were represented in vaccines. These results may support future Spn colonization studies among middle-aged and older adults.

Detection and Molecular Characterization of Rotavirus Infections in Children and Adults with Gastroenteritis from Vojvodina, Serbia.

Rotaviruses (RV) are the leading cause of gastroenteritis in infants, young children, and adults, responsible for serious disease burden. In the period 2012-2018, a cross-sectional study was conducted using stool samples collected from patients with acute gastroenteritis from Vojvodina, Serbia. We described age and gender distribution, as well as seasonal patterns of RV prevalence. Out of 1853 included stool samples, RV was detected in 29%. Hospitalized children between 1-2 years old were especially affected by RV infection (45%). The highest prevalence of infection was observed during the colder, winter/spring months. We compared sequenced representative G and P genotypes circulating in Serbia with vaccine strains and determined their genetic similarity. Genotype combination G2P[4] was the most prevalent (34.6%), followed by G2P[8] (24.1%) and G1P[8] (21.1%). Given that several epitopes were conserved, neutralization motifs among circulating strains can be characterized as sufficiently matching vaccine strains Rotarix™ and RotaTeq™, but existing antigenic disparities should not be overlooked. The present results contribute to a better insight into the prevalence of rotavirus infection in our region and point out the need for epidemiological surveillance of rotaviruses before the introduction of vaccines. These data can help formulate future vaccine strategies in Serbia.

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.

Pneumococcal nasopharyngeal carriage in children under 5 years of age at an outpatient healthcare facility in Novi Sad, Serbia during the COVID-19 pandemic.

Objectives: To assess whether pneumococcal nasopharyngeal carriage among children aged 24-60 months reduced during the coronavirus disease 2019 (COVID-19) pandemic in Novi Sad, Serbia, and to investigate the overall prevalence of carriage, serotype distribution and dominant serotypes 2-3 years after the introduction of pneumococcal conjugate vaccine 10. Design and methods: This prospective, observational study was conducted in February-March 2020, September-November 2020 and April-June 2021, enabling the comparison of results in the pre-pandemic/early pandemic period with two periods during the COVID-19 pandemic. Pneumococci were identified by standard microbiological methods. Serotype identification was performed using conventional multiplex polymerase chain reaction assays. Results: Among 1623 children tested, 515 (31.7%, 95% confidence interval 29.4-34.0%) carried pneumococci. A significant increase in prevalence was found between February-March 2020 and September-November 2020 (P=0.0085), with no difference found between September-November 2020 and April-June 2021 (P=0.0524). Pneumococcal colonization was significantly higher in children who were fully vaccinated and among children who attended day care centres. The dominant serotypes were 15B, 6B, 19F, 11A, 6C, 6A, 3, 23F and 19A, representing 66.4% of all isolates. Conclusions: This study found that pneumococcal nasopharyngeal carriage in children aged 24-60 months was high before the COVID-19 pandemic, and then increased during the pandemic. This rules out a major role of COVID-19 in the suppression of carriage and, probably, transmission.