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BackgroundData on the rate and severity of reinfections with SARS-CoV-2 in real-world settings are scarce and the effects of booster vaccination on reinfection risk are unknown.MethodsIn a retrospective cohort study, all SARS-CoV-2 laboratory-confirmed residents of Vojvodina, registered in the database of the Institute of Public Health of Vojvodina, 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 risk of reinfection was visualized with Kaplan-Meier plots. To examine whether vaccination protected from reinfection, the subset of Vojvodina residents with primary infection in 2020 (March 6–December 31) were matched (1:2) with controls without reinfection.ResultsUntil January 31, 2022, 13,792 reinfections were recorded among 251,104 COVID-19 primary infections (5·49%). Most reinfections (86·8%) were recorded in January 2022. Reinfections were mostly mild (99·2%). Hospitalizations were uncommon (1·08% vs. 3·70% in primary infection) and COVID-19 deaths were very rare (n=20, case fatality rate 0·15%). The overall incidence rate of SARS-CoV-2 reinfections was 5·99 (95% CI 5·89-6·09) per 1,000 person-months for those who survived the first three months after primary infection. The reinfection risk was estimated as 0·76% at six months, 1·36% at nine months, 4·96% at 12 months, 16·7% at 15 months, and 18·9% at 18 months. Among 34 second reinfections, none resulted in hospitalization or death. 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 those who received a third (booster) vaccine dose.ConclusionsSARS-CoV-2 reinfections were exceptionally uncommon until the end of 2021 but became common with the advent of the Omicron variant. Very few reinfections were severe. A vaccination booster dose may modestly reduce reinfection risk.

We give a simple proof of the Kernel theorem for the space of tempered ultradistributions of Beurling -Komatsu type, using the characterization of Fourier-Hermite coefficients of the elements of the space. We prove in details that the test space of tempered ultradistributions of Beurling -Komatsu type can be identified with the space of sequences of ultrapolynomal falloff and its dual space with the space of sequences of ultrapolynomial growth. As a consequence of the Kernel theorem we have that the Weyl transform can be extended on a space of tempered ultradistributions of Beurling -Komatsu type.

AimTo 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.MethodsThis 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.ResultsIn 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).ConclusionPlasma homocysteine levels have a greater clinical significance in the prevention of thrombosis and managing its complications than MTHFR 677 genotyping.

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.