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Background. We aimed to estimate COVID-19 Vaccine Effectiveness (VE) and its durability against severe disease (intubation) and death in the Greek population, for all vaccines currently in use. Methods. Nationwide active surveillance and vaccination registry data between January 2021 - April 2022 were used to estimate VE via quasi-Poisson regression as one minus Incidence Rate Ratio, adjusted for age and calendar time. Interaction terms were included to assess VE by age group, by variant (delta vs omicron) and by time since vaccination (compared to the first month after vaccination). Results. VE results are summarized in Figures 1-3. After 2-doses (of any vaccine) VE was >95% against delta and >85% against omicron in the 15-59 and 60-79 age groups, but waned significantly at 6 months by 5-10% in the 15-59 group and 15-20% in the 60-79 group. In the 80+ age group, 2-dose VE was much lower against omicron at around 60%, waning to 50% at 6 months. With 3 vaccine doses VE surged to >95% against both delta and omicron in all age groups except 80+, who had VE against omicron of =90%;however there was again substantial waning at 6 months by about 10-15% in all groups. In the 80+ age group, VE against omicron dropped to 81.4% (95% CI 76.7-85.2%) for death and 57.7% (95% CI 38.5-70.9%) for intubation. There was little to no evidence of variation in VE between combinations of different vaccines (BNT162b2, mRNA-1273, ChAdOx1 nCov-19 and Ad26.COV2.S), although the majority of the population received 2- or 3-dose BNT162b2. Vaccination prevented an estimated 39,018 COVID-19 deaths (95% CI: 37,791- 40,608) over the study period. Conclusion. COVID-19 vaccination remains extremely effective in preventing severe disease and death, even in the context of the omicron variant, as long as 3 doses have been administered. Even after 3 doses, however, effectiveness wanes substantially in the course of 6 months. Additional strategies will be therefore needed in order to minimize COVID-19 mortality and morbidity, including boosting doses especially in the elderly, improved vaccines, early diagnosis and treatment of high-risk groups and measures to reduce community transmission of current or novel SARS-CoV-2 immune escape variants.
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Background. The emergence of the highly infectious Omicron variant at the end of 2021 changed the pandemic dynamics, also causing an increase inCOVID-19 re-infections. Our aim was to investigate suspected re-infections and the characteristics of individuals with multiple infections since the beginning of the pandemic until early April 2022. Methods. Since the beginning of the pandemic, all COVID-19 positive tests (Rapid Antigen Tests - RAT and PCR) have been recorded in the COVID-19 National Electronic Registry. Cases were extracted and reported daily based on the first positive test for each individual (first episodes). Establishment of the Omicron variant, associated with a re-infection surge, triggered the decision for modifying case definition and applying a different methodology to include suspected re-infections in the number of daily reported cases after 3rd of April. Suspected re-infections were defined as 'positive PCR or RAT sample >=90 days following a previous positive PCR or RAT'. The number of re-infections were estimated retrospectively on the Registry's data. Results. Overall, 6,348 suspected re-infections were recorded up to 15/12/2021 (0.6% of the laboratory confirmed tests), whereas until 3/4/22 the number was increased at 115.201, raising the percentage to 4%. Distribution of the number of reinfections per ISO week is depicted in Figure 1, along with the number of first episodes. Suspected re-infections stand for 3.7% of the total number of first episodes recorded up to 3/4/22 (3,077,711), with their integration having a noticeable effect on case counting. Among them, 99.3% represent a second episode of infection and 0.7% multiple re-infections. Median age of suspected re-infections was 29 years (IQR: 19-44) (Figure 2). The median length of the time interval between two subsequent infections was 8 months (IQR: 5-12) (Figure 3). Conclusion. Up until mid-December 2021, COVID-19 re-infection was uncommon, changing to higher rates after the emergence of Omicron variant, thus documenting the immune escape capacity of this variant. Besides the improvement in surveillance, knowledge about the re-infections and their characteristics provides a proxy of the immune protection from previous exposure to COVID-19, against circulating variants over time.
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Background: In modern transfusion therapy, whole blood is used only in certain limited circumstances and trust is placed in the use of specific blood components (BCs). BC must be processed using appropriate validated procedures, including measures to avoid contamination and microbial growth in the initial and final prepared BCs (Directive 2005/62/EC, Annex 6.42). Consequently, methods of centrifugation of whole blood, filtration of leukocytes, washing and irradiation must be specified. Aim(s): We analyse national data on non-haemolytic pyrexial and allergic reactions related to blood transfusion reported to the Coordinating Haemovigilance Centre and Surveillance of Transfusion (SKAEM) of the Hellenic National Public Health Organization (EODY) by hospital Transfusion Departments in 2010-2020, in relation to the processing procedures applied using conventional blood bank methodologies. The results of an automated blood processing system employed in two hospital blood banks are also discussed in view of the national policy for stepwise implementation of a centralized automated processing procedure aiming to improve the quality and safety of blood transfusion. Method/Study: Annual haemovigilance data for all adverse reactions associated with BCs transfusion are reported to SKAEM using standardized questionnaires. Protocols are in line with International Haemovigilance Network guidelines and ISBT definitions of the types of adverse reactions associated with blood transfusion. The processing procedures used are: buffy coat removal, leukocyte depletion after storage, pre-storage leukodepletion, red cell washing in additive solution, and irradiation. The Reveos Automated Blood System (Terumo BCT) was also used, processing 4 units of whole blood to two components (plasma and red cells) or three main components (plasma, concentrated red cells and interim platelet unit) according to the manufacturer's instructions. Both protocols collect a Leukopak unit containing the main leukocyte fraction which is discarded. The resulting RCC is further leukoreduced by gravity using the Reveos in-line filter. Consistent leukoreduction of plasma is done through the simultaneous centrifugation/ extraction step of this method. Result(s): 13005 adverse reactions (AR) associated with the transfusion of 7 894 054 blood components were reported. Febrile nonhaemolytic transfusion reactions were 43.7% and allergic 37%. The distribution of febrile reactions in relation to processing procedure was: in RBCs with buffy coat 61.7%, without buffy coat 10.9%, leukodepletion after storage 16.5%, leukodepletion pre-storage 6.7%, washing 4.1% and irradiation 0.1%. Results from the use of the Reveos Automated Processing System (Terumo BCT) by the National Blood Centre for processing the blood collected and used by two large HBBs over a two-year period showed a statistically significant reduction of pyrexial reactions (p = 0.044 in one hospital and 0.002 in the other) in comparison with the relevant data before the use of this system. The corresponding difference in the allergic reactions was not statistically significant. Conclusion(s): This study demonstrates high incidence of pyrexial nonhaemolytic and allergic reactions associated with the use of blood components processed without leukodepletion, particularly during the COVID-19 pandemic when blood transfusion services were shortstaffed owing to re-assignment to other duties. Compliance with Good Practice Guidelines and improvement of blood processing and safety by automation should be a national priority.
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Background and aims: Coronavirus disease 2019 (COVID-19) is associated with increased thrombosis prevalence. However, there are insufficient data supporting the appropriate anticoagulation (AC) dose in COVID-19. Methods: We conducted a living systematic review and meta-analysis on the effects of different low molecular weight heparin (LMWH) and/ or fondaparinux doses on mortality, thrombotic and hemorrhagic events in COVID-19 patients. MEDLINE, Scopus, Embase, Cochrane Library, Cochrane COVID-19 study register, European Union Drug Regulating Authorities Clinical Trials Database and ClinicalTrials.gov were searched to detect observational cohort studies and randomized-controlled clinical trials (RCTs) comparing difference doses of LMWH or fondaparinux among confirmed COVID-19 cases. Results: Thirty-one eligible studies (6 RCTs and 25 cohort studies) with 11,430 hospitalized patients were included. No association was found between AC and mortality during the following comparisons: a) no AC versus any AC;b) prophylactic versus higher than prophylactic AC;c) prophylactic versus therapeutic AC;d) intermediate versus therapeutic AC;and e) lower than therapeutic versus therapeutic AC. However, the risk for all-cause mortality was higher in patients receiving prophylactic versus intermediate AC (OR=2.01;95%CI: 1.19-3.39). No associations were detected between the intensity of AC and the risk of thrombotic and hemorrhagic events, except the significantly lower risk for hemorrhage in patients on prophylactic compared to higher AC doses. Conclusions: The risk for all-cause mortality was significantly higher in patients receiving prophylactic AC compared to those on an intermediate dose of AC. These results should be interpreted in light of the moderate quality and heterogeneity of the included studies.
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Background: The speed of development of COVID-19 vaccines, and the need to balance their effectiveness versus possible complications, raised doubts over vaccine acceptance in the first period of the national vaccination campaign aiming at herd immunity against SARSCoV- 2. In the field of transfusion medicine, timely vaccination of the blood donor population represents a powerful measure in the general strategy to sustain blood collection and optimize the blood supply. Aims: To explore perceptions and attitudes of blood donors towards SARS-CoV-2 vaccination, in comparison to the general population. Methods: Donors in 20 blood collection services throughout Greece in May-October 2021 answered voluntarily and confidentially a structured questionnaire, covering: donor demographics;date and type of blood donation;frequency of donation;history of COVID-19;SARSCoV- 2 vaccination including type and doses;reasons for getting vaccinated or not;satisfaction with the vaccination procedure;side effects;feelings after vaccination;certainty about return to normality;and recommending vaccination to others. Hesitancy and beliefs leading to not getting vaccinated, worries over future side effects, and not recommending vaccination to others were also investigated. Results: Completed questionnaires were received from 3361 blood donors (61% response rate) aged 18-65 years during blood sessions at mobile sites and within hospitals. Respondents were mainly males (72%). A very high proportion (92%) of responders had completed high school of higher education and the majority resided in large cities. Almost half were regular donors. A small proportion (5.4%) had undergone a mild COVID19 infection and 17.3% mentioned COVID-19 in a relative. 52% had already been vaccinated. The proportion vaccinated increased steadily throughout the study. Vaccine acceptance was highest in males 45-54 years old and in females 18-24 and 50-59 years old. All four EMA approved vaccines (Pfizer, Moderna, Astra Zeneca and Johnson) were used. Mild complications were reported by 21% of vaccinated donors after the first dose and 19% after the second. Thirty-five donors reported fever and local pain at the vaccination site after both doses. The vast majority (79%) of vaccinated donors were very satisfied with the vaccination procedure and only 10 complained. After vaccination, 20% of donors felt safe and protected against COVID-19 and 55% intended to continue all recommended personal protective measures in their families and felt satisfaction for doing the right thing. Among unvaccinated respondents, 48% were awaiting their appointment, 19% were undecided, 16% were afraid of complications, a few said that they were waiting for more information about the beneficial effect of the vaccines, or that COVID-19 is not a severe disease, and 10% did not specify their reasons. In the general population of Greece surveyed in May 2021 in the Flash Eurobarometer study, COVID-19 vaccination acceptance was 59%. The proportion of those with negative perception and attitude towards vaccination was 12%. Key reasons for getting vaccinated or not were similar to those found in blood donors. Summary/Conclusions: The benefits of vaccination and the need to continue all personal protection measures were highly recognized by blood donors, whether already vaccinated or awaiting vaccination. The perceptions and attitudes towards vaccination against COVID-19, especially of regular donors, are compatible with their high social, altruistic and humanitarian behaviour.
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During the COVID-19 pandemic, wastewater-based epidemiology (WBE) has been engaged to complement medical surveillance and in some cases to also act as an early diagnosis indicator of viral spreading in the community. Most efforts worldwide by the scientific community and commercial companies focus on the formulation of protocols for SARS-CoV-2 analysis in wastewater and approaches addressing the quantitative relationship between WBE and medical surveillance are lacking. In the present study, a mathematical model is developed which uses as input the number of daily positive medical tests together with the highly non-linear shedding rate curve of individuals to estimate the evolution of global virus shedding rate in wastewater along calendar days. A comprehensive parametric study by the model using as input actual medical surveillance and WBE data for the city of Thessaloniki (~700,000 inhabitants, North Greece) during the outbreak of November 2020 reveals the conditions under which WBE can be used as an early warning tool for predicting pandemic outbreaks. It is shown that early warning capacity is different along the days of an outbreak and depends strongly on the number of days apart between the day of maximum shedding rate of infected individuals in their disease cycle and the day of their medical testing. The present data indicate for Thessaloniki an average early warning capacity of around 2 days. Moreover, the data imply that there exists a proportion between unreported cases (asymptomatic persons with mild symptoms that do not seek medical advice) and reported cases. The proportion increases with the number of reported cases. The early detection capacity of WBE improves substantially in the presence of an increasing number of unreported cases. For Thessaloniki at the peak of the pandemic in mid-November 2020, the number of unreported cases reached a maximum around 4 times the number of reported cases.
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COVID-19 , SARS-CoV-2 , Humans , Pandemics , Wastewater , Wastewater-Based Epidemiological MonitoringABSTRACT
BACKGROUND: A novel coronavirus (2019-nCoV) associated with human to human transmission and severe human infection has been recently reported from the city of Wuhan in China. Our objectives were to characterize the genetic relationships of the 2019-nCoV and to search for putative recombination within the subgenus of sarbecovirus. METHODS: Putative recombination was investigated by RDP4 and Simplot v3.5.1 and discordant phylogenetic clustering in individual genomic fragments was confirmed by phylogenetic analysis using maximum likelihood and Bayesian methods. RESULTS: Our analysis suggests that the 2019-nCoV although closely related to BatCoV RaTG13 sequence throughout the genome (sequence similarity 96.3%), shows discordant clustering with the Bat_SARS-like coronavirus sequences. Specifically, in the 5'-part spanning the first 11,498 nucleotides and the last 3'-part spanning 24,341-30,696 positions, 2019-nCoV and RaTG13 formed a single cluster with Bat_SARS-like coronavirus sequences, whereas in the middle region spanning the 3'-end of ORF1a, the ORF1b and almost half of the spike regions, 2019-nCoV and RaTG13 grouped in a separate distant lineage within the sarbecovirus branch. CONCLUSIONS: The levels of genetic similarity between the 2019-nCoV and RaTG13 suggest that the latter does not provide the exact variant that caused the outbreak in humans, but the hypothesis that 2019-nCoV has originated from bats is very likely. We show evidence that the novel coronavirus (2019-nCov) is not-mosaic consisting in almost half of its genome of a distinct lineage within the betacoronavirus. These genomic features and their potential association with virus characteristics and virulence in humans need further attention.