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Relevance. The high infectivity and mutagenicity of SARS-CoV-2, combined with the relative short duration of the immune response, means that the problem of controlling the incidence of COVID-19 will continue to be relevant. Aims. To plan anti-epidemic measures, you need to know the quantitative value of the basic reproductive number (R0), however, the available methods for estimating the R0 made it possible to estimate it only for the initial version of SARS-CoV-2. In this regard, the task was set to develop a method for estimating R0 for current pathogen variants based on the rate of change from one variant to another, including both viruses and bacteria. Materials and methods. A modification of the SIR model for two variants of SARS-CoV-2 and actual data on the incidence of COVID-19 and the results of sequencing the virus SARS-CoV-2 isolated in Moscow are used. Results. It was found that for the SARS-CoV-2 Delta variant R0 was about 10, and for the current Omicron variants it exceeds 30. Discussion. In contrast to existing methods, the proposed method allows one to estimate R0 in the context of anti-epidemic measures, as well as by the dynamics of morbidity in a population with a collective immune status, taking into account the typical structure of the circulating SARS-CoV-2. Conclusion. The proposed method makes it possible to estimate the change in the basic reproductive number of the SARS-CoV-2 based on the rate of displacement of one variant by another

Aim. To assess whether delayed coronary artery stenting (CAS) can reduce the slow/no-reflow incidence in patients with ST-segment elevation myocardial infarction (STEMI) and massive thrombosis (TTG ≥3) of the infarct-related coronary artery (IRCA) compared with immediate CAS within primary PCI.Material and methods. Out of 3651 primary PCIs performed for acute STEMI in the period from January 2016 to May 2020 at the Mytishchi City Clinical Hospital, the retrospective analysis included 105 patients with massive IRCA thrombosis (TTG ≥3). The patients were divided into two groups: first group (n=55) — delayed CAS, second group (n=50) — immediate CAS. In the immediate CAS group, the PCI procedure ended with routine stent implantation, and in the delayed CAS group, stent implantation was delayed for at least 5 days.Results. In the delayed CAS group in comparison with immediate one, the slow/no-reflow phenomenon developed much less frequently in the form of a significant increase in the prevalence of TIMI 3 flow, better myocardial perfusion of myocardial blush grade (MBG) 2-3 (81,8 vs 64%; odds ratio (OR) 2,53; p=0,039) and ST segment resolution ≥70% (87,3% vs 58%; OR 4,97; p=0,001).Conclusion. Delayed CAS in patients with STEMI with massive thrombosis (TTG ≥3) of IRCA reduces the risk of slow/no-reflow phenomenon and can be considered as a possible alternative treatment vs immediate CAS, provided that stable coronary flow is restored before TIMI 3.

Aim. To study clinical results and safety of delayed vs urgent stenting with application of modern antithrombotic drugs in massive coronary thrombosis in patients with ST-elevation acute myocardial infarction (STEMI).Material and methods. Totally, 28 STEMI patients included, age 52 (25-77) y.o., of those males 80% (n=23), who, during January 2014 to February 2016, in first 6-12 hours from the onset of the disease, received endovascular treatment with purpose to recover adequate blood flow without urgent stent implanting into infarct-related artery. Minimal invasive strategy with the aim to recover antegrade blood flow up to TIMI 2-3 was done for 14 (50%) patients. In all patients, after restoring of the antegrade flow, there was thrombus, visualized in artery lumen, with TIMI thrombus grade score (TTG) ≥3. Another criteria of efficacy was resolving of ST elevation by ≥50%. As antiplatelet support during the intervention all patients received the combination of IIb/IIIa blockers (eptifibatide) and 600 mg clopidogrel or 180 mg ticagrelor. Second coronary arteriography (CAG) was done in up to 5 days.Results. By 4,0±1,0 day, blood flow TIMI 2-3 in infarction-related artery was secure in 100% patients; there was marked decrease of the grade of target stenosis in infarction-related artery from 77,8±10,2% to 50,5±19,5%; decrease by its length from 21,5±8,5 to 15,5±5,5 mm; increase of the reference diameter of artery from 3,1±0,8 to 3,5±0,75 mm, and thrombosis bride by TTG — from 3,9 to 0,9. By the data from CAG, stenting of the target segment was done in 8 (29%) patients, and in 3 (10%) stenting done based on the data from intravascular ultrasound. In 17 (61%) patients the infarction-related stenosis was non-significant. In the group of delayed stenting there was no cases of no/slow-reflow development. At hospital stage of management, there were no cardiovascular events in the observation group.Conclusion. In patients with massive thrombosis of infarction-related artery (TTG ≥3) and restored antegrade coronary flow TIMI 2-3, the delayed stenting is a safe and effective strategy of treatment at hospital stage.

Background: Thrombocytopenia is one of the most common toxicities of chemotherapy, causing symptoms ranging from mild petechiae to debilitating bleeding. These effects can lead to treatment delay and discontinuation, which subsequently affects outcome. The data on chemotherapy-induced thrombocytopenia is scarce, especially from the developing world, and until now there is no consensus on the appropriate management of this complication. Aim: The aim of this study was to evaluate chemotherapy-induced thrombocytopenia in pediatric patients with acute lymphoblastic leukemia. Methods: Medical records of acute lymphoblastic leukemia patients who were diagnosed and treated in 2019 at the only center for pediatric hematologic and oncologic disorders in Armenia - the Pediatric Cancer and Blood Disorders Center of Armenia - were retrospectively reviewed. Results: A total of 29 patients with acute lymphoblastic leukemia, who were subsequently treated with International BFM (Berlin, Frankfurt, Muenster) Study Group acute lymphoblastic leukemia IC BFM 2009 protocol and achieved remission, were included in the current study. 17 (58%) patients were males. The median age was 4.5y. and range, 18 months - 17 years. 5 patients had T-acute lymphoblastic leukemia and 24 patients, Bacute lymphoblastic leukemia. During induction therapy, 11 patients (38%) developed critical thrombocytopenia with platelet counts ranging from 21×10 3/L to 46×10³/L. During consolidation therapy, 16 patients (55%) developed moderate thrombocytopenia, with platelet counts ranging from 70×10³/L to 86×10³/L and 6 (21%) patients had critical thrombocytopenia, with platelet counts ranging from 27×10³/L to 36×10³/L. During the re-induction phase of therapy, 21 (72%) patients developed critical chemotherapy-induced thrombocytopenia with platelet counts ranging from 13×10³/L to 45×10³/L. Isolated thrombocytopenia occurred in 3 (10%) of the patients. Thrombocytopenia was managed by platelet transfusion. The median (range) pre-transfusion platelet count was 10×109/L (5×109 -13×109/L) and increased significantly post-transfusion to 22×109/L. Conclusions: During the course of therapy the vast majority of patients with acute lymphoblastic leukemia developed clinically significant thrombocytopenia. Although our study is small and involves the cases from one year, it includes all the acute lymphoblastic leukemia patients treated in Armenia. The study clearly shows that chemotherapy-induced thrombocytopenia is a very common complication of acute lymphoblastic leukemia therapy and larger studies needed to explore these findings. [ABSTRACT FROM AUTHOR]