Analysis of SARS-CoV-2 Cases, COVID-19 Outcomes and Vaccinations, during the Different SARS-CoV-2 Variants in Greece

Since the emergence of the SARS-CoV-2 Omicron variant, many issues have arisen. We report SARS-CoV-2 vaccinations, SARS-CoV-2 cases and COVID-19 outcomes in Greece during weeks 2–26 of 2021 (Alpha variant period), weeks 27–51 of 2021 (Delta variant period) and week 51 of 2021 to week 27 of 2022 (Omicron variant period). The average weekly cases were higher during the Omicron period vs. the Delta (25,354.17 cases/week) and Alpha periods (11,238.48 cases/week). The average weekly vaccinations were lower in the Omicron period (26,283.69/week) than in the Alpha and Delta period. Joinpoint regression analysis identified that the trend of SARS-CoV-2 cases increased by 88.5% during the rise of the Omicron wave in Greece. The trend of the intensive care unit (ICU) admissions related to COVID-19 decreased by 5.0% immediately after the rise of Omicron while the trend of COVID-19-related deaths decreased by 8.1% from the 5th week of the Omicron wave until the end of the study. For vaccinations, an increasing trend of 8.3% was observed in the first half of 2021 (weeks 18–25/2021), followed by a decreasing trend in weeks 26–43/2021. For the weeks before and during the early rise of Omicron (44/2021–1/2022), we identified an increasing trend of 10.7% and for weeks 2–27/2022 we observed a decreasing trend of 18.1%. Unfortunately, we do not have available data about the vaccination status of the SARS-CoV-2 cases, ICU admissions or deaths. Our findings suggest that the Omicron variant is associated with increased transmissibility and reduced morbidity and mortality despite the previous increase in the trend of SARS-CoV-2 vaccinations

Μελέτη της παθογένειας της ιδιοπαθούς πνευμονικής ίνωσης: το μονοπάτι της αγγειογένεσης και ο ρόλος της λεπτίνης

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive fibrotic lung disease which is associated with lack of effective treatment and thus, poor survival. Despite extensive research, IPF pathogenesis remains unknown. Multiple mechanisms have been proposed to play a role in IPF pathogenesis, including abnormal vascular repair and remodeling, and inflammation. Indeed, there is a body of evidence suggesting that in IPF, the impairment of repair reendothelization mechanisms following alveolar injury may lead to destruction in lung architecture and fibrosis. Notably, failure of reendothelization may induce loss of the alveolar-capillary barrier integrity which might be considered as the point after which fibrosis may be inevitable. On the other hand, studies have suggested that inflammation may play a role in the development of IPF. Histology demonstrates the presence of inflammatory cells close to areas of dense fibrosis. Recent findings suggest that chronic inflammation resulting from repetitive microinjury may participate in the initiation of the fibrotic process. Endothelial progenitor cells (EPCs) represent a subset of bone marrow-derived stem cells which may be essential in parenchymal repair and reconstitution of the damaged vascular bed. Two subtypes of EPCs exist. Late EPCs may differentiate into mature endothelial cells and repair injured blood vessels while “early EPCs” (i.e. EPCs that grow into colony forming units (CFU) on fibronectin following 5-7 days culture) secrete angiogenic cytokines such as VEGF and enhance the angiogenic process. The important role of EPCs in lung repair has been suggested from previous studies in animal models and humans. Notably, reduced EPCs numbers have been associated with persistent fibrotic changes, not due to IPF, in humans following lung injury. In this respect, one might argue that EPCs might also play a pivotal role in IPF. However, data in IPF patients are sparse to few reports. Leptin is a protein that is mainly produced by adipose tissue, however it is secreted in lower amounts by various other tissues. Recent investigations have identified the lung as a leptin responsive and producing organ, while extensive research has been published concerning leptins role in the respiratory system. Beyond its role in the regulation of food intake and body composition, leptin exerts pro-inflammatory properties. According to experimental data, increased leptin levels enhance liver inflammation and fibrogenesis. In fact, leptin is essential for the induction of transforming growth factor-β (TGF-β) in the context of chronic liver injury that ultimately leads to liver fibrosis. In this respect, one could argue that leptin may enhance lung fibrogenesis. However literature lacks data concerning leptins role in pulmonary fibrosis. Adiponectin, that is the most abundant gene product of adipose tissue, demonstrates anti-inflammatory properties. Several studies have shown that adiponectin antagonizes leptins profibrotic properties. Adiponectin inhibits the TGF-β induced expression of profibrogenic cytokines (e.g. CTGF) while adiponectin knock-out mice exhibit induced renal interstitial fibrosis that is ameliorated by adiponectin replacement. The latter observations mirror the hypothesis that adiponectin may have a protective effect in lung fibrosis, however there are no reports in the literature examining this effect. In this respect, we aimed to investigate the role of angiogenesis and inflammation in the development of IPF. For the analysis of the role of angiogenesis we assessed the levels of EPCs in IPF patients and controls. Furthermore, we sought to investigate soluble VEGF serum levels and mRNA VEGF expression of EPCs in order to provide further insight in the proangiogenic activity and mobilization of EPCs from the bone marrow. We included 23 IPF patients and 15 healthy volunteers in the study. All patients underwent clinical examination, pulmonary function tests, and arterial blood gas (ABGs) analysis and echocardiography. IPF patients exhibited statistically significantly decreased number of early EPCs CFU per well when compared to controls. The number of colonies per well correlated negatively statistically significantly with P(A-a)O2 in IPF patients. When we evaluated EPCs levels according to the degree of systolic pulmonary arterial pressure (sPAP) we found that IPF patients with sPAP≥35mmHg had statistically significant reduced number of early EPCs colonies when compared with patients with sPAP<35mmHg. Quantification of mRNA levels by real-time PCR showed that IPF patients present statistically significant increased relative VEGF expression when compared with controls. In order to examine the role of inflammation in IPF we assessed the concentrations of leptin and adiponectin in serum, and the levels of leptin in exhaled breath condensate (EBC) and bronchoalveolar lavage fluid (BAL) of IPF patients and controls and we sought to investigate their association with clinical indices of disease severity. The study population consisted of 37 IPF patients and 22 healthy volunteers. Serum leptin presented no significant differences in male and female patients when compared to healthy volunteers of the same gender. Serum adiponectin levels did not differ significantly between patients and controls. Leptin/adiponectin ratio in male patients was positively associated with PaO2. Leptin levels when adjusted for BMI in male patients with PaO2<65 were significantly reduced as compared to male patients with PaO2≥65mmHg. Additionally, leptin/adiponectin ratio in male IPF patients with PaO2<65 mmHg was significantly reduced vs male patients with PaO2≥65 mmHg. Furthermore, leptin/adiponectin ratio in male subjects was negatively correlated with 6-minute walking distance. Finally, EBC and BAL leptin levels were not significantly correlated with the corresponding serum leptin levels. We conclude that early EPCs levels are reduced in IPF patients compared to controls and that EPCs derived from IPF patients, exhibit increased endogenous VEGF production. Notably, early EPCs levels were significantly lower in patients with increased pressure in the pulmonary circulation. In this respect, the findings of the present study underline potentially significant implications of early EPCs in IPF and might provide further insight in the understanding of the pathogenesis of the disease. Additionally, the present study provides evidence suggesting a possible role of leptin in the severity and/or pathogenesis of IPF. Notably, leptin and leptin/adiponectin ratio were significantly reduced in male IPF patients with hypoxia. Additionally, we did not observe any significant correlation of leptin EBC and BAL levels with serum leptin concentrations suggesting that leptin may be locally produced within the lung. However, the mechanisms and physiological relevance of the aforementioned findings deserve further investigation.Η Ιδιοπαθής Πνευμονική Ίνωση (ΙΠΙ, Idiopathic Pulmonary Fibrosis) είναι μια χρόνια νόσος η οποία οδηγεί σε καταστροφή της αρχιτεκτονικής του πνευμονικού παρεγχύματος. Σύμφωνα με τις διεθνείς θέσεις ομοφωνίας, η ΙΠΙ ορίζεται σαν μια ειδική μορφή χρόνιας και προοδευτικά επιδεινούμενης ινοποιού διάμεσης πνευμονίας με άγνωστη αιτιολογία. Σε μια προσπάθεια εύρεσης αποτελεσματικής θεραπείας, πολλές έρευνες τα τελευταία χρόνια έχουν επικεντρωθεί στη μελέτη της παθογένειας της ΙΠΙ, ωστόσο ως σήμερα η παθογένεια της νόσου παραμένει άγνωστη. Μια από τις πιο πρόσφατες υποθέσεις υποστηρίζει ότι κάποιο άγνωστο ως σήμερα ερέθισμα κινητοποιεί διάφορους μηχανισμούς που δρουν παράλληλα με τελικό αποτέλεσμα την εναπόθεση κολλαγόνου στο πνευμονικό παρέγχυμα και την καταστροφή της αρχιτεκτονικής του. Δύο από αυτούς τους μηχανισμούς είναι η αγγειογένεση και η φλεγμονή. Τα κυκλοφορούντα πρόδρομα ενδοθηλιακά κύτταρα (circulating endothelial progenitor cells, EPCs) αποτελούν μια ομάδα κυττάρων του μυελού των οστών που είναι απαραίτητα για την επιδιόρθωση των βλαβών του αγγειακού δικτύου κατά την ενήλικη ζωή. Τα κύτταρα αυτά έχουν την ικανότητα να διαφοροποιούνται προς ώριμα ενδοθηλιακά κύτταρα και να εκκρίνουν παράγοντες που επάγουν την αγγειογένεση.Η λεπτίνη είναι μια πρωτεΐνη που παράγεται κυρίως από τα λιποκύτταρα σε ποσά ανάλογα του συνολικού ποσοστού λίπους του οργανισμού. Η λεπτίνη παράγεται, σε μικρότερη όμως έκταση, και από άλλα όργανα και ιστούς όπως ο πνεύμονας. Η λεπτίνη είναι σημαντικός μεσολαβητής της ανοσολογικής απάντησης και έχει προφλεγμονώδη δράση. Πρόσφατες μελέτες δείχνουν ότι η λεπτίνη έχει σημαντική προϊνωτική δράση στο ήπαρ καθώς είναι απαραίτητη για την επαγωγή του transforming growth factor-β. Η αδιπονεκτίνη που παράγεται και εκείνη από το λιπώδη ιστό έχει αντιφλεγμονώδεις ιδιότητες και ανταγωνίζεται την προϊνωτική δράση της λεπτίνης. Με βάση τα παραπάνω δεδομένα αποφασίσαμε να μελετήσουμε το ρόλο της αγγειογένεσης και της φλεγμονής στην παθογένεια της ΙΠΙ. Για την ανάλυση της συμμετοχής της αγγειογένεσης στην ΙΠΙ μετρήσαμε τα επίπεδα EPCs σε ασθενείς με ΙΠΙ και υγιείς εθελοντές. Επιπλέον, μετρήσαμε τα επίπεδα του αγγειακού ενδοθηλιακού αυξητικού παράγοντα (vascular endothelial growth factor, VEGF) στον ορό προκειμένου να αξιολογήσουμε διαταραχές στο μηχανισμό κινητοποίησης των EPCs από το μυελό των οστών. Τέλος θελήσαμε να μελετήσουμε τη δράση των EPCs και έτσι εξετάσαμε την ενδογενή παραγωγή VEGF από τα EPCs σε ασθενείς και μάρτυρες. Στη μελέτη συμμετείχαν 23 ασθενείς με ΙΠΙ και 15 υγιείς εθελοντές. Διαπιστώθηκε στατιστικά σημαντικά μικρότερος αριθμός αποικιών EPCs ανά τριβλίο στην ομάδα των ασθενών συγκριτικά με τους μάρτυρες. O αριθμός των αποικιών στην ομάδα των ασθενών παρουσίαζε στατιστικά αρνητική σημαντική συσχέτιση με τη P(A-a)O2 Επίσης, παρατηρήθηκε ότι οι ασθενείς με πνευμονική υπέρταση (sPAP≥35mmHg) παρουσίαζαν στατιστικά σημαντικά μικρότερο αριθμό αποικιών έναντι εκείνων χωρίς πνευμονική υπέρταση. Επιπλέον, παρατηρήσαμε στατιστικά σημαντικά μεγαλύτερα επίπεδα ενδογενούς έκφρασης του VEGF από τα EPCs στην ομάδα των ασθενών σε σχέση με τους εθελοντές. Για την ανάλυση της συμμετοχής της φλεγμονής στην παθογένεια της ΙΠΙ μετρήσαμε τα επίπεδα λεπτίνης και αδιπονεκτίνης σε ασθενείς με ΙΠΙ και διερευνήσαμε κατά πόσο τα επίπεδα αυτά σχετίζονται με τη βαρύτητα της νόσου όπως αυτή εκφράζεται από τα αέρια αίματος, το λειτουργικό έλεγχο του αναπνευστικού κ.α.. Επίσης, προσδιορίσαμε τα επίπεδα λεπτίνης στο συμπύκνωμα εκπνεόμενου αέρα (exhaled breath condensate, EBC) και στο βρογχοκυψελιδικό έκπλυμα (bronchoalveolar lavage, BAL) ασθενών με ΙΠΙ. Στην παρούσα μελέτη συμμετείχαν 37 ασθενείς με ΙΠΙ και 22 υγιείς εθελοντές. Τα επίπεδα της λεπτίνης δε διέφεραν στατιστικά σημαντικά στους άνδρες και στις γυναίκες ασθενείς συγκριτικά με τους μάρτυρες αντίστοιχου φύλου. Ωστόσο, ο λόγος λεπτίνης/αδιπονεκτίνης στους άνδρες ασθενείς σχετίζεται θετικά στατιστικά σημαντικά με τη PaO2. Μετά από προσαρμογή για τα σωματομετρικά χαρακτηριστικά, παρατηρήσαμε ότι τα επίπεδα λεπτίνης των ανδρών ασθενών με PaO2<65 ήταν στατιστικά σημαντικά μειωμένα συγκριτικά με τους άνδρες ασθενείς με PaO2≥65mmHg. Επιπλέον, ο λόγος λεπτίνης/αδιπονεκτίνης στους άνδρες ασθενείς με PaO2<65 mmHg ήταν στατιστικά σημαντικά μειωμένος συγκριτικά με τους άνδρες ασθενείς με PaO2≥65 mmHg. Επίσης παρατηρήσαμε ότι στην ομάδα των ανδρών ασθενών τα επίπεδα λεπτίνης παρουσιάζουν αρνητική συσχέτιση με την απόσταση που διανύθηκε κατά τη δοκιμασία βάδισης 6 λεπτών. Επιπλέον, ο λόγος λεπτίνης/αδιπονεκτίνης παρουσίαζε στατιστικά σημαντική θετική συσχέτιση με τη συνολική βαθμολογία του ερωτηματολογίου saint George Respiratory Questionnaire που αντικατοπτρίζει χειρότερη σχετιζόμενη με την κατάσταση της υγείας ποιότητα ζωής. Τέλος, δεν παρατηρήθηκε στατιστικά σημαντική συσχέτιση των επιπέδων λεπτίνης στο EBC και στο BAL με τη συγκέντρωση λεπτίνης στον ορό που λήφθηκε σύγχρονα. Συμπερασματικά, διαπιστώσαμε ότι οι ασθενείς με Ιδιοπαθή Πνευμονική Ίνωση παρουσιάζουν μειωμένα επίπεδα κυκλοφορούντων πρόδρομων ενδοθηλιακών κυττάρων, τα οποία συσχετίζονται με τη βαρύτητα της νόσου και την ανάπτυξη πνευμονικής υπέρτασης. Τα κυκλοφορούντα πρόδρομα ενδοθηλιακά κύτταρα των ασθενών με ΙΠΙ παρουσιάζουν αυξημένη έκφραση VEGF. Επιπλέον, διαπιστώσαμε ότι η λεπτίνη και ο λόγος λεπτίνης/αδιπονεκτίνης είναι μειωμένοι σε ασθενείς με ΙΠΙ και χαμηλή PaO2. Επίσης τα επίπεδα λεπτίνης στο EBC δε σχετίζονται στατιστικά σημαντικά με τα αντίστοιχα επίπεδα στον ορό γεγονός που υποδεικνύει ότι η λεπτίνη παράγεται στον πνεύμονα ανεξάρτητα από τη συστηματική έκκρισή της. Τέλος διαπιστώσαμε ότι ο λόγος λεπτίνης/αδιπονεκτίνης σχετίζεται με περιορισμένη ικανότητα για άσκηση (όπως αντανακλάται από τη δοκιμασία βάδισης) και χειρότερη ποιότητα ζωής. Τα ευρήματά μας χρήζουν περαιτέρω διερεύνησης προκειμένου να επιβεβαιωθεί ο ρόλος της αγγειογένεσης και της λεπτίνης στην παθογένεια της Ιδιοπαθούς Πνευμονικής Ίνωσης

Registry Systems for COVID-19 Vaccines and Rate of Acceptability for Vaccination Before and After Availability of Vaccines in 12 Countries: A Narrative Review

Registry systems play a key role in promoting vaccination campaigns in the general population. In the present narrative review, we provide data from 12 12 countries for vaccination acceptance before the availability of COVID-19 vaccines and vaccination coverage once it is available. We selected a randomized representative sample of 12 countries from WHO regions and 194 total members by the Open Epi Random Program. We observed the results with different levels of vaccine acceptability between the studies that were performed before the availability of a vaccine against COVID-19 and the vaccination coverage after the availability of the COVID-19 vaccine. All the registry systems that were developed for the recent pandemic achieved the initial functional goals. Twelve months after the vaccination campaign has begun, varying results were reported for vaccination coverage against COVID-19 vaccines with rates as high as 98% (subjects with at least one dose of vaccine) in the United Arabic Emirates, and as low as 24% in South Africa. The United Arabic Emirates stood as the leader of the world with the highest number of vaccinations 88% fully vaccinated citizens followed by Canada with 80% fully vaccinated citizens. The available data suggest that vaccine registry systems could help increase vaccination coverage and aim in the control of future outbreaks

Registry Systems for COVID-19 Vaccines and Rate of Acceptability for Vaccination Before and After Availability of Vaccines in 12 Countries: A Narrative Review

Registry systems play a key role in promoting vaccination campaigns in the general population. In the present narrative review, we provide data from 12 12 countries for vaccination acceptance before the availability of COVID-19 vaccines and vaccination coverage once it is available. We selected a randomized representative sample of 12 countries from WHO regions and 194 total members by the Open Epi Random Program. We observed the results with different levels of vaccine acceptability between the studies that were performed before the availability of a vaccine against COVID-19 and the vaccination coverage after the availability of the COVID-19 vaccine. All the registry systems that were developed for the recent pandemic achieved the initial functional goals. Twelve months after the vaccination campaign has begun, varying results were reported for vaccination coverage against COVID-19 vaccines with rates as high as 98% (subjects with at least one dose of vaccine) in the United Arabic Emirates, and as low as 24% in South Africa. The United Arabic Emirates stood as the leader of the world with the highest number of vaccinations 88% fully vaccinated citizens followed by Canada with 80% fully vaccinated citizens. The available data suggest that vaccine registry systems could help increase vaccination coverage and aim in the control of future outbreaks

The Use of a Novel Quantitative Marker of Echogenicity of Pleural Fluid in Parapneumonic Pleural Effusions

Background. Thoracic ultrasound is an essential tool in the daily clinical care of pleural effusions and especially parapneumonic pleural effusions (PPEs), in terms of diagnosis, management, and follow-up. Hypoechogenicity index (HI) is a quantitative marker of pleural fluid echogenicity. We aimed to examine associations of HI with pleural inflammation in patients with PPE. Methods. All patients included underwent a thoracic ultrasound with HI determination at the first day of their admission for a PPE. Thoracentesis was performed in all patients. Demographics, laboratory measurements, and clinical data were collected prospectively and recorded in all subjects. Results. Twenty-four patients with PPE were included in the study. HI was statistically significantly correlated with intensity of inflammation as suggested by pleural fluid LDH (p<0.001, r = −0.831), pleural fluid glucose (p=0.022, r = 0.474), and pleural fluid pH (p<0.001, r = 0.811). HI was correlated with ADA levels (p=0.005, r = −0.552). We observed a statistically significant correlation of HI with pleural fluid total cell number (p<0.001, r = −0.657) and polymorphonuclears percentage (p=0.02, r = −0.590), as well as days to afebrile (p=0.046, r = −0.411), duration of chest tube placement (p<0.001, r = −0.806), and days of hospitalization (p=0.013, r = −0.501). Discussion. HI presents a fast, easily applicable, objective, and quantitative marker of pleural inflammation that reliably reflects the intensity of pleural inflammation and could potentially guide therapeutic management of PPE

Automated Oxygen Delivery in Hospitalized Patients with Acute Respiratory Failure: A Pilot Study

Background and Objectives. Despite its’ proven benefits, oxygen therapy may be complicated with potential adverse events such as hypoxemia or hyperoxia-driven hypercapnia. Automated oxygen delivery systems may aid in avoiding these complications. The scope of the present study is to test the efficacy and safety of a new automated oxygen delivery device. Methods. This study included 23 patients with acute respiratory failure (ARF) hospitalized in the Respiratory Medicine Department of the University Hospital of Larissa. Both patients with purely hypoxemic or hypercapnic ARF were included. Automated oxygen administration was performed with Digital Oxygen Therapy, a new closed-loop system designed to automatically adjust oxygen flow according to target oxygen saturation (SpO2) of 88–92% for hypercapnic patients and 92–96% for purely hypoxemic patients with ARF. The device was applied for 4 hours. Arterial blood gas analysis was performed at 1 hour and 3 hours following the device application. Results. Mean age was 72.91 ± 13.91 years. Twelve patients were male, and 11 were female. The majority of patients suffered from hypercapnic respiratory failure (n=13, 56.5%). At 1 hour and 3 hours, SpO2 and PaO2 displayed excellent correlation (p<0.001, r = 0.943, and p<0.001, r = 0.954, respectively). We did not observe any adverse events associated with the device. Conclusions. Our results indicate that automated oxygen treatment is feasible and safe in hospitalized patients with acute respiratory failure. Further studies are required in order to assess the long-term effects of automated oxygen delivery systems

Pathophysiological Aspects of Aging in Venous Thromboembolism: An Update

The aim of this review is to highlight all the factors that associate venous thromboembolism (VTE) with aging. Elderly people are characterized by a higher incidence of thrombosis taking into account the co-existing comorbidities, complications and fatality that arise. Based on the Virchow triad, pathophysiological aspects of venous stasis, endothelium injury and hypercoagulability in elderly people (≥65 years) are described in detail. More precisely, venous wall structure, nitric oxide (NO) and endothelin-1 expression are impaired in this age group. Furthermore, an increase in high-molecular-weight kininogen (HMWK), prekallikrein, factors V, VII, VIII, IX and XI, clot lysis time (CLT) and von Willebrand factor (vWF) is observed. Age-dependent platelet dysfunction and changes in anticoagulant factors are also illustrated. A “low-grade inflammation stage” is delineated as a possible risk factor for thrombosis in the elderly. Consequently, clinical implications for frail elderly people related to diagnosis, treatment, bleeding danger and VTE recurrence emerge. We conclude that aging is an acquired thrombotic factor closely related to pathophysiological changes

Analysis of SARS-CoV-2 Cases, COVID-19 Outcomes and Vaccinations, during the Different SARS-CoV-2 Variants in Greece

Since the emergence of the SARS-CoV-2 Omicron variant, many issues have arisen. We report SARS-CoV-2 vaccinations, SARS-CoV-2 cases and COVID-19 outcomes in Greece during weeks 2–26 of 2021 (Alpha variant period), weeks 27–51 of 2021 (Delta variant period) and week 51 of 2021 to week 27 of 2022 (Omicron variant period). The average weekly cases were higher during the Omicron period vs. the Delta (25,354.17 cases/week) and Alpha periods (11,238.48 cases/week). The average weekly vaccinations were lower in the Omicron period (26,283.69/week) than in the Alpha and Delta period. Joinpoint regression analysis identified that the trend of SARS-CoV-2 cases increased by 88.5% during the rise of the Omicron wave in Greece. The trend of the intensive care unit (ICU) admissions related to COVID-19 decreased by 5.0% immediately after the rise of Omicron while the trend of COVID-19-related deaths decreased by 8.1% from the 5th week of the Omicron wave until the end of the study. For vaccinations, an increasing trend of 8.3% was observed in the first half of 2021 (weeks 18–25/2021), followed by a decreasing trend in weeks 26–43/2021. For the weeks before and during the early rise of Omicron (44/2021–1/2022), we identified an increasing trend of 10.7% and for weeks 2–27/2022 we observed a decreasing trend of 18.1%. Unfortunately, we do not have available data about the vaccination status of the SARS-CoV-2 cases, ICU admissions or deaths. Our findings suggest that the Omicron variant is associated with increased transmissibility and reduced morbidity and mortality despite the previous increase in the trend of SARS-CoV-2 vaccinations