Low Transmission Rate Research Articles

COVID-19 and vertical transmission: assessing the expression of ACE2/TMPRSS2 in the human fetus and placenta to assess the risk of SARS-CoV-2 infection.

BackgroundPregnant women have been identified as a potentially at‐risk group concerning COVID‐19 infection, but little is known regarding the susceptibility of the fetus to infection. Co‐expression of ACE2 and TMPRSS2 has been identified as a prerequisite for infection, and expression across different tissues is known to vary between children and adults. However, the expression of these proteins in the fetus is unknown.MethodsWe performed a retrospective analysis of a single cell data repository. The data were then validated at both gene and protein level by performing RT‐qPCR and two‐colour immunohistochemistry on a library of second‐trimester human fetal tissues.FindingsTMPRSS2 is present at both gene and protein level in the predominantly epithelial fetal tissues analysed. ACE2 is present at significant levels only in the fetal intestine and kidney, and is not expressed in the fetal lung. The placenta also does not co‐express the two proteins across the second trimester or at term.InterpretationThis dataset indicates that the lungs are unlikely to be a viable route of SARS‐CoV2 fetal infection. The fetal kidney, despite presenting both the proteins required for the infection, is anatomically protected from the exposure to the virus. However, the gastrointestinal tract is likely to be susceptible to infection due to its high co‐expression of both proteins, as well as its exposure to potentially infected amniotic fluid.Tweetable abstractThis work provides detailed mechanistic insight into the relative protection & vulnerabilities of the fetus & placenta to SARS‐CoV‐2 infection by scRNAseq & protein expression analysis for ACE2 & TMPRSS2. The findings help to explain the low rate of vertical transmission.

Creation of a software and hardware product of a real-time system for collecting, accounting and managing data transmission of an intelligent transport system in context of the IoT

Some aspects of the functioning of modern microcontrollers of the Internet of Things in conditions that are close to real-time systems are reviewed in the article. Attention is paid to the aspects of the theory of physical data transmission, the significance of the delay metrics in the data transmission path is substantiated and emphasized. These delays (in view of the generalization of measurement results) determine the control accuracy and controllability of the data processing system as a whole, and also affect the reliability of the results. The process of formalization of the architectural template of a data collecting and accounting system for a control device (which is widespread in intelligent transport systems and the Internet of things) is described. The practical application of the approach in synchronous control through the implementation of a web interface and a control language in a microprocessor system (which can be possible at low traffic transmission rates) is substantiated. In conclusion, a generalization of the scope of application of the developed specialized computer system in transport field is given.

SARS-CoV-2 in infant urine and fecal samples after in utero COVID-19 exposure.

BackgroundCoronavirus disease 2019 (COVID-19) is a pandemic that has and will continue to affect many pregnant women. Knowledge regarding the risk of vertical transmission is limited. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) real-time reverse transcriptase-polymerase chain reaction (RT-PCR) of nasopharyngeal swabs typically have been used to confirm the diagnosis among infants, but whether the virus can be detected in other biological specimens, and therefore potentially transmitted in other ways, is unknown. Positive SARS-CoV-2 RT-PCR has been reported from feces and urine from adult patients. We hypothesize that the presence of SARS-CoV-2 in infant urine and fecal samples after prenatal COVID-19 exposure is low.MethodsWe examined the presence of SARS-CoV-2 RNA using RT-PCR in urine and fecal samples among 42 infants born to SARS-CoV-2-infected mothers during different stages of pregnancy.ResultsA urine sample was collected from 39 of 42 infants and fecal samples from all 42 infants shortly after birth. Although the majority of the women had the symptomatic disease (85.6%), we were unable to detect the presence of SARS-CoV-2 virus from any infant urine or fecal samples.ConclusionsSARS-CoV-2 was not detected in infant urine or feces after maternal infection during pregnancy, providing further evidence for low rates of perinatal transmission.Impact SARS-CoV-2 was not detected in the urine or feces of infants of mothers with COVID-19 during various time points in pregnancy.This study provides further evidence for low rates of perinatal transmission of SARS-CoV-2.Results help to provide guidance on perinatal care practices for infants exposed to COVID-19 in utero.

The Determinants of the Low COVID-19 Transmission and Mortality Rates in Africa: A Cross-Country Analysis.

Background: More than 1 year after the beginning of the international spread of coronavirus 2019 (COVID-19), the reasons explaining its apparently lower reported burden in Africa are still to be fully elucidated. Few studies previously investigated the potential reasons explaining this epidemiological observation using data at the level of a few African countries. However, an updated analysis considering the various epidemiological waves and variables across an array of categories, with a focus on African countries might help to better understand the COVID-19 pandemic on the continent. Thus, we investigated the potential reasons for the persistently lower transmission and mortality rates of COVID-19 in Africa.Methods: Data were collected from publicly available and well-known online sources. The cumulative numbers of COVID-19 cases and deaths per 1 million population reported by the African countries up to February 2021 were used to estimate the transmission and mortality rates of COVID-19, respectively. The covariates were collected across several data sources: clinical/diseases data, health system performance, demographic parameters, economic indicators, climatic, pollution, and radiation variables, and use of social media. The collinearities were corrected using variance inflation factor (VIF) and selected variables were fitted to a multiple regression model using the R statistical package.Results: Our model (adjusted R-squared: 0.7) found that the number of COVID-19 tests per 1 million population, GINI index, global health security (GHS) index, and mean body mass index (BMI) were significantly associated (P < 0.05) with COVID-19 cases per 1 million population. No association was found between the median life expectancy, the proportion of the rural population, and Bacillus Calmette–Guérin (BCG) coverage rate. On the other hand, diabetes prevalence, number of nurses, and GHS index were found to be significantly associated with COVID-19 deaths per 1 million population (adjusted R-squared of 0.5). Moreover, the median life expectancy and lower respiratory infections rate showed a trend towards significance. No association was found with the BCG coverage or communicable disease burden.Conclusions: Low health system capacity, together with some clinical and socio-economic factors were the predictors of the reported burden of COVID-19 in Africa. Our results emphasize the need for Africa to strengthen its overall health system capacity to efficiently detect and respond to public health crises.

Thickness evaluation of AlOx barrier layers for encapsulation of flexible PV modules in industrial environments by normal reflectance and machine learning

AbstractFlexible photovoltaic (PV) devices, such as those based on Cu (In,Ga)Se2 (CIGS) and perovskites, use polymeric front sheets for encapsulation that do not provide sufficient protection against the environment. The addition of nanometric AlxO layers by spatial atomic layer deposition (S‐ALD) to these polymeric materials can highly improve environmental protection due to their low water vapor transmission rate and is a suitable solution to be applied in roll‐to‐roll industrial production lines. A precise control of the thickness of the AlOx layers is crucial to ensure an effective water barrier performance. However, current thickness evaluation methods of such nanometric layers are costly and complex to incorporate in industrial environments. In this context, the present work describes and demonstrates a novel characterization methodology based on normal reflectance measurements and either on control parameter‐based calibration curves or machine learning algorithms that enable a precise, low‐cost, and scalable assessment of the thickness of AlOx nanometric layers. In particular, the proposed methodology is applied for precisely determining the thickness AlOx nanolayers deposited on three different substrates relevant for the PV industry: monocrystalline Si, Cu (In,Ga)Se2 multistack flexible modules, and polyethylene terephthalate (PET) flexible encapsulation foil. The proposed methodology demonstrates a sensitivity &lt;10 nm and acquisition times ≤100 ms which makes it compatible with industrial monitoring applications. Additionally, a specific design for in‐line integration of a normal reflectance system into a roll‐to‐roll production line for thickness control of nanometric layers is defined and proposed.

Call Model and Test-Verification Methods for PS-LTE Core Equipment

Existing technologies in disaster and safety communication networks (DSCNs) face problems such as narrow bandwidth, low transmission rate, and difficulty in securing channels. Conversely, public safety long-term evolution (PS-LTE) technology provides high-speed, low-latency, quick-setup, and high-security data access for multimedia-based mission-critical services. To perform tests on each unit of core equipment with PS-LTE technology, a new call model such as push-to-talk, which is a service representing PS-LTE, is required. Moreover, objective and consistent metrics and methods are required for administering tests on the unique functions of DSCNs newly constructed with PS-LTE technology. This paper proposes a call model for the core facilities of DSCNs established in Korea, and it also suggests test and verification methods for all the areas of PS-LTE, including mission-critical push-to-talk, evolved multimedia broadcast and multicast service, and coverage and quality assessment for wireless services.

Ergodic stationary distribution and practical application of a hybrid stochastic cholera transmission model with waning vaccine‐induced immunity under nonlinear regime switching

Considering the effect of stochasticity including white noise and colored noise, this paper aims to study a hybrid stochastic cholera epidemic model with waning vaccine‐induced immunity and nonlinear telegraph perturbations. First, we derive a critical value related to the basic reproduction number of the deterministic model. The key aim of this paper is to generalize the θ‐stochastic criterion method proposed by the recent work (Han et al. in Chaos Solit Fract 140:110238, 2020) to eliminate nonlinear telegraph perturbations. Next, via constructing several θ‐stochastic Lyapunov functions and using the generalized method, we further prove that the stochastic model have a unique ergodic stationary distribution under . Results show that the prevention and control of cholera epidemic depend on low transmission rate and small telegraph perturbations. Finally, the corresponding numerical simulations are performed to illustrate our analytical results and a practical application on the Somalia cholera outbreak is shown at the end of this paper.

A changing demographic - Ten years of HIV care.

We aimed to benchmark the quality of care and describe characteristics of patients newly attending the HIV clinic at differing time points over the past 10years, against the Infectious Disease Society of America HIV/AIDS performance measures. We performed a retrospective analysis of records for patients newly attending the HIV clinic in 2011, 2016 and 2018. There was an increase in male attendees in 2018 and 2016 compared to 2011 (88%, 88% vs. 59% p < .001), viral suppression rates were 97%, 83% and 99% (p < .001), respectively. We observed an increase in patients of South American origin over time. Acquisition risk changed, with increased proportion of MSM (24% in 2011 vs 78% in 2018, p < .001), lower rates of heterosexual (20% in 2018 vs 48% in 2011, p < .001) and IDU transmission (1.5% in 2018 vs 24% in 2011, p < .001). There were lower rates of Chlamydia trachomatis and Neisseria gonorrhoeae testing in 2018 (72%, p < .001), compared to 2016 (84%) and 2011 (83%). Hepatitis B virus vaccination and pneumococcal vaccine rates are declining (p < .001). We demonstrate the changes in both ethnicity and risk of acquisition over time, high rates of antiretroviral therapy prescription and viral suppression, and highlight the importance of health prevention with sexual health screening and vaccination in this population.

Early infant diagnosis of HIV-I infection using dried blood spots among children born to seropositive mothers in Federal Medical Centre (FMC) Lokoja

Early diagnosis of Human immunodeficiency virus (HIV) in infants provides a critical opportunity to strengthen follow-up of HIV- exposed children using dried blood spots and assure early access to antiretroviral treatment for infected children. This study aimed to determine the prevalence of HVI-1 infection in infants born to HIV-seropositive mothers. Early infant diagnosis of HIV sub-type I was carried out using on dried blood spots of 286 babies born to HIV-I seropositive mothers attending the Federal Medical Centre, Lokoja - Kogi State, Nigeria, between the months of July to December, 2013. Data obtained was analyzed using Gene Amp PCR System 9700. The overall rate of HIV-I vertical transmission from infected mothers to their babies was 14.5%. High transmission rates 63.5%was seen in babies whose mothers could not get any form of interventions with the least transmission rates seen in babies whose mothers either took HAART or were one form of ARV or the other (0 – 1.0%). Babies who took nevirapine as prophylaxis after delivery had lower rate (1%) of transmission. From the 30 women that mix-fed their babies, 6.7% transmission rate was recorded.Lack of antiretroviral drugs by HIV-I positive pregnant women was found to be associated with high rate of HIV-I transmission (p&lt;0.05). Early intervention of mother to child transmission of HIV-1 infection using Highly Active Antiretroviral Therapy, exclusive breastfeeding practice as well as constant visit to Tertiary Hospitals for counseling and management of HIV infection reduced the rate of infection among the infants born to seropositive mothers.

Rationale for Mass Masking in Controlling the COVID-19 Pandemic.

The rapid spread of the coronavirus disease 2019 (COVID-19) into a global pandemic caught the world unprepared. Previously effective measures for containing disease outbreaks were overwhelmed, necessitating strict controls such as lockdowns or curfews. Among the disease control interventions, community mass masking was one of the highly controversial issues with differing opinions on its indications or effectiveness from different health authorities around the world. Regions where community mass masking was timely introduced were associated with lower transmission rates, and more effective disease control. In this article, we discuss the evidence on the effectiveness, and rationale for community mass masking to prevent the COVID-19 transmission. Areas for further research to define the role of mass masking in light of the COVID-19 pandemic will be suggested. This would help policy makers in formulating mass masking policies.

Protective Effects of Astodrimer Sodium 1% Nasal Spray Formulation against SARS-CoV-2 Nasal Challenge in K18-hACE2 Mice.

Strategies to combat COVID-19 require multiple ways to protect vulnerable people from infection. SARS-CoV-2 is an airborne pathogen and the nasal cavity is a primary target of infection. The K18-hACE2 mouse model was used to investigate the anti-SARS-CoV-2 efficacy of astodrimer sodium formulated in a mucoadhesive nasal spray. Animals received astodrimer sodium 1% nasal spray or PBS intranasally, or intranasally and intratracheally, for 7 days, and they were infected intranasally with SARS-CoV-2 after the first product administration on Day 0. Another group was infected intranasally with SARS-CoV-2 that had been pre-incubated with astodrimer sodium 1% nasal spray or PBS for 60 min before the neutralisation of test product activity. Astodrimer sodium 1% significantly reduced the viral genome copies (>99.9%) and the infectious virus (~95%) in the lung and trachea vs. PBS. The pre-incubation of SARS-CoV-2 with astodrimer sodium 1% resulted in a significant reduction in the viral genome copies (>99.9%) and the infectious virus (>99%) in the lung and trachea, and the infectious virus was not detected in the brain or liver. Astodrimer sodium 1% resulted in a significant reduction of viral genome copies in nasal secretions vs. PBS on Day 7 post-infection. A reduction in the viral shedding from the nasal cavity may result in lower virus transmission rates. Viraemia was low or undetectable in animals treated with astodrimer sodium 1% or infected with treated virus, correlating with the lack of detectable viral replication in the liver. Similarly, low virus replication in the nasal cavity after treatment with astodrimer sodium 1% potentially protected the brain from infection. Astodrimer sodium 1% significantly reduced the pro-inflammatory cytokines IL-6, IL-1α, IL-1β, TNFα and TGFβ and the chemokine MCP-1 in the serum, lung and trachea vs. PBS. Astodrimer sodium 1% nasal spray blocked or reduced SARS-CoV-2 replication and its sequelae in K18-hACE2 mice. These data indicate a potential role for the product in preventing SARS-CoV-2 infection or for reducing the severity of COVID-19.

Information encoding and transmission profiles of first-language (L1) and second-language (L2) speech.

Inspired by information theoretic analyses of L1 speech and language, this study proposes that L1 and L2 speech exhibit distinct information encoding and transmission profiles in the temporal domain. Both the number and average duration of acoustic syllables (i.e., intensity peaks in the temporal envelope) were automatically measured from L1 and L2 recordings of standard texts in English, French, and Spanish. Across languages, L2 acoustic syllables were greater in number (more acoustic syllables/text) and longer in duration (fewer acoustic syllables/second). While substantial syllable reduction (fewer acoustic than orthographic syllables) was evident in both L1 and L2 speech, L2 speech generally exhibited less syllable reduction, resulting in low information density (more syllables with less information/syllable). Low L2 information density compounded low L2 speech rate yielding very low L2 information transmission rate (i.e., less information/second). Overall, this cross-language comparison establishes low information transmission rate as a language-general, distinguishing feature of L2 speech.

The importation and establishment of community transmission of SARS-CoV-2 during the first eight weeks of the South African COVID-19 epidemic.

BackgroundWe describe the epidemiology of COVID-19 in South Africa following importation and during implementation of stringent lockdown measures.MethodsUsing national surveillance data including demographics, laboratory test data, clinical presentation, risk exposures (travel history, contacts and occupation) and outcomes of persons undergoing COVID-19 testing or hospitalised with COVID-19 at sentinel surveillance sites, we generated and interpreted descriptive statistics, epidemic curves, and initial reproductive numbers (Rt).FindingsFrom 4 March to 30 April 2020, 271,670 SARS-CoV-2 PCR tests were performed (462 tests/100,000 persons). Of these, 7,892 (2.9%) persons tested positive (median age 37 years (interquartile range 28–49 years), 4,568 (58%) male, cumulative incidence of 13.4 cases/100,000 persons). Hospitalization records were found for 1,271 patients (692 females (54%)) of whom 186 (14.6%) died. Amongst 2,819 cases with data, 489/2819 (17.3%) travelled internationally within 14 days prior to diagnosis, mostly during March 2020 (466 (95%)). Cases diagnosed in April compared with March were younger (median age, 37 vs. 40 years), less likely female (38% vs. 53%) and resident in a more populous province (98% vs. 91%). The national initial Rt was 2.08 (95% confidence interval (CI): 1.71–2.51).InterpretationThe first eight weeks following COVID-19 importation were characterised by early predominance of imported cases and relatively low mortality and transmission rates. Despite stringent lockdown measures, the second month following importation was characterised by community transmission and increasing disease burden in more populous provinces.

Pertactin contributes to shedding and transmission of Bordetella bronchiseptica

Whooping cough is resurging in the United States despite high vaccine coverage. The rapid rise of Bordetella pertussis isolates lacking pertactin (PRN), a key vaccine antigen, has led to concerns about vaccine-driven evolution. Previous studies showed that pertactin can mediate binding to mammalian cells in vitro and act as an immunomodulatory factor in resisting neutrophil-mediated clearance. To further investigate the role of PRN in vivo, we examined the functions of pertactin in the context of a more naturally low dose inoculation experimental system using C3H/HeJ mice that is more sensitive to effects on colonization, growth and spread within the respiratory tract, as well as an experimental approach to measure shedding and transmission between hosts. A B. bronchiseptica pertactin deletion mutant was found to behave similarly to its wild-type (WT) parental strain in colonization of the nasal cavity, trachea, and lungs of mice. However, the pertactin-deficient strain was shed from the nares of mice in much lower numbers, resulting in a significantly lower rate of transmission between hosts. Histological examination of respiratory epithelia revealed that pertactin-deficient bacteria induced substantially less inflammation and mucus accumulation than the WT strain and in vitro assays verified the effect of PRN on the induction of TNF-α by murine macrophages. Interestingly, only WT B. bronchiseptica could be recovered from the spleen of infected mice and were further observed to be intracellular among isolated splenocytes, indicating that pertactin contributes to systemic dissemination involving intracellular survival. These results suggest that pertactin can mediate interactions with immune cells and augments inflammation that contributes to bacterial shedding and transmission between hosts. Understanding the relative contributions of various factors to inflammation, mucus production, shedding and transmission will guide novel strategies to interfere with the reemergence of pertussis.

Rotary LED Transmitter for Improving Data Transmission Rate of Image Sensor Communication

This study focuses on image sensor communication (ISC), which is a form of visible light communication, using a light-emitting diode (LED) and a camera as the transmitting and receiving device, respectively. In an ISC system, the receiver captures optical signals transmitted by blinking LEDs as an image and demodulates the data using the captured image. The ISC system can spatially separate signals and noises in the image, thus providing superior anti-interference ability. However, because the speed of ISC depends on the shooting speed of the camera, the receiver suffers from a low data transmission rate when a low-speed camera is used. To improve the data rate of ISC, we have developed a rotary LED transmitter. This transmitter cylindrically rotates the blinking LEDs during the exposure time of the camera. The camera captures multiple blinking states of LEDs as afterimages in a single image, thereby increasing the amount of data received per image. In this paper, we propose an ISC system using a rotary LED transmitter and present an experiment for the evaluation of the data rate. The result indicates that the data rate of the rotary LED transmitter is 60 times that of the conventional method.

Does high adherence to contact precautions lead to low in-hospital transmission of multi-drug-resistant micro-organisms in the endemic setting?

Conflicting results have been published on the impact of contact precautions (CPs) on reduction of transmission of multi-drug-resistant micro-organisms (MDROs) in the endemic setting. Ambiguous definitions coupled with low adherence partly explain these differences. We prospectively monitored the level of adherence to CPs and aimed to relate it to in-hospital transmission of MDROs. Between January 2016 and March 2018, all patients under CPs underwent continuous monitoring of adherence to CPs by routine on-site visits on days 0, 3 and 7 after initiating CPs using a standardized checklist. The protocol included 10 interventions that were routinely checked such as CP sign at the door as well as wearing of gowns and gloves upon entry to the patient room. Patients requiring CPs were defined as colonized or infected with MDROs (meticillin-resistant Staphylococcus aureus (MRSA), non-Escherichia coli extended-spectrum beta lactamase (ESBL) Enterobacterales, vancomycin-resistant enterococci (VRE) and carbapenem-resistant Gram-negative micro-organisms (CRGN)) as well as patients infected with respiratory viruses, norovirus, scabies and hypervirulent strains of Clostridioides difficile. Overall, data from 13,756 CP records from 1378 visits of 812 patients were analysed. Adherence varied between 93% and 100% for each intervention, except for "separate space for contaminated material" with an adherence of 5.3-6.1%. The incidence of in-hospital transmission during the study period was extremely low for MRSA, VRE, non-E.coli ESBL Enterobacterales and CRGN with 0.00-0.064 cases/1000 patient days. High adherence coupled with continuous monitoring of CPs correlated with a very low in-hospital transmission rate. These results indicate that CPs are highly effective if routine monitoring of adherence is implemented.

A Routing Query Algorithm Based on Time-Varying Relationship Group in Opportunistic Social Networks

With the fast development of IoT and 5G technologies, opportunity social networks composed of portable mobile devices have become a hot research topic in recent years. However, arbitrary node movement in opportunity networks and the absence of end-to-end pathways make node communication unstable. At the same time, the problem of ignoring human social preferences and relying on wrong message relay nodes lead to a low data transmission rate and high network overhead. Based on the above issues, we propose a time-varying relationship groups-based routing query algorithm for mobile opportunity networks (Time-varying Relationship Groups, TVRGs). Firstly, we construct the relationship groups based on the time-varying characteristics according to the intimacy between users. Secondly, we calculate the importance of nodes by their connectivity time and communication frequency. Finally, we find the suitable message relay nodes according to the similarity of node weights and their action trajectories and design the routing query algorithm accordingly. The simulation results show that the algorithm can vastly improve the message query success rate, effectively improve the data transmission efficiency, and reduce the average delay and system overhead compared with the existing routing algorithms.

User‐centric data communication service strategy for 5G vehicular networks

To solve the problems of unbalanced network loads, poor network throughput, and low user transmission rate in 5th generation (5G) vehicular networks, a user-centric data communication service (UCDCS) strategy is proposed for 5G vehicular networks. First, the UCDCS model is established. The access roadside unit group (ARSUG) is updated in real-time according to predictions of vehicle mobility. Then, a data communication service resource allocation algorithm based on game theory that considers the network load cost, throughput cost, and vehicle benefit is developed. Based on the results of the algorithm, roadside unit (RSU) selection based on entropy weight is performed and the best RSU for data communication is selected according to the different service preferences of each vehicle. This improves the transmission rate for users and realizes network load balance to ensure the quality of service for users. The simulation results show that the transmission rate of the UCDCS strategy is 35.16%, 23.46%, and 47.74% higher than those of the traditional handover management (THOM), improved mobility management (IMM), and network-centric network selection strategies (NCNS), respectively; correspondingly, the link reliability is at least 0.07% higher, and the network delay is at least 5.96% smaller for the UCDCS strategy.

Safety of emergency, elective and day case operating during the winter period at East Suffolk and North Essex NHS Foundation Trust: lessons from the outcomes of 4,254 surgical patients from the first COVID-19 wave.

There is limited evidence on perioperative outcomes of surgical patients during the COVID-19 pandemic to inform continued operating into the winter period. We retrospectively analysed the rate of 30-day COVID-19 transmission and mortality of all surgical patients in the three hospitals in our trust in the East of England during the first lockdown in March 2020. All patients who underwent a swab were swabbed on or 24 hours prior to admission. There were 4,254 patients and an overall 30-day mortality of 0.99%. The excess surgical mortality in our region was 0.29%. There were 39 patients who were COVID-19 positive within 30 days of admission, 12 of whom died. All 12 were emergency admissions with a length of stay longer than 24 hours. There were three deaths among those who underwent day case surgery, one of whom was COVID-19 negative, and the other two were not swabbed but not suspected to have COVID-19. There were two COVID-19 positive elective cases and none in day case elective or emergency surgery. There were no COVID-19 positive deaths in elective or day case surgery. There was a low rate of COVID-19 transmission and mortality in elective and day case operations. Our data have allowed us to guide patients in the consent process and provided the evidence base to restart elective and day case operating with precautions and regular review. A number of regions will be similarly affected and should perform a review of their data for the winter period and beyond.

Molecular Epidemiology of SARS-CoV-2 in Greece Reveals Low Rates of Onward Virus Transmission after Lifting of Travel Restrictions Based on Risk Assessment during Summer 2020.

ABSTRACTThe novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread rapidly during the first months of 2020 and continues to expand in multiple areas across the globe. Molecular epidemiology has provided an added value to traditional public health tools by identifying SARS-CoV-2 clusters or providing evidence that clusters based on virus sequences and contact tracing are highly concordant. Our aim was to infer the levels of virus importation and to estimate the impact of public health measures related to travel restrictions to local transmission in Greece. Our phylogenetic and phylogeographic analyses included 389 full-genome SARS-CoV-2 sequences collected during the first 7 months of the pandemic in Greece and a random collection in five replicates of 3,000 sequences sampled globally, as well as the best hits to our data set identified by BLAST. Phylogenetic trees were reconstructed by the maximum likelihood method, and the putative source of SARS-CoV-2 infections was inferred by phylogeographic analysis. Phylogenetic analyses revealed the presence of 89 genetically distinct viruses identified as independent introductions into Greece. The proportion of imported strains was 41%, 11.5%, and 8.8% during the three periods of sampling, namely, March (no travel restrictions), April to June (strict travel restrictions), and July to September (lifting of travel restrictions based on thorough risk assessment), respectively. The results of phylogeographic analysis were confirmed by a Bayesian approach. Our findings reveal low levels of onward transmission from imported cases during summer and underscore the importance of targeted public health measures that can increase the safety of international travel during a pandemic.IMPORTANCE Our study based on current state-of-the-art molecular epidemiology methods suggests that virus screening and public health measures after the lifting of travel restrictions prevented SARS-CoV-2 onward transmission from imported cases during summer 2020 in Greece. These findings provide important data on the efficacy of targeted public health measures and have important implications regarding the safety of international travel during a pandemic. Our results can provide a roadmap about prevention policy in the future regarding the reopening of borders in the presence of differences in vaccination coverage, the circulation of the virus, and the presence of newly emergent variants across the globe.