Heterogeneous price adjustments among Airbnb hosts amid COVID-19: Evidence from Barcelona.

COVID-19-induced travel restrictions have led to a sharp drop in Airbnb bookings. Confronted with a decrease in demand, hosts have implemented heterogeneous price responses. This study evaluates the different price adjustments developed by professional and non-professional hosts. Considering the city of Barcelona as the case study, I exploit monthly longitudinal data for 24,000 different Airbnb listings observed between June 2020 and April 2021. Using hedonic regressions with listing and neighbourhood fixed effects, I show that professional hosts have reduced prices to a greater extent, especially during the worst months of the pandemic. The findings support intertemporal price discrimination among professional hosts, which seem to adjust prices faster to meet demand and better adapt to market conditions.

Collective emotions during the COVID-19 outbreak.

The COVID-19 pandemic has exposed the world's population to unprecedented health threats and changes to social life. High uncertainty about the novel disease and its social and economic consequences, together with increasingly stringent governmental measures against the spread of the virus, likely elicited strong emotional responses. We analyzed the digital traces of emotional expressions in tweets during 5 weeks after the start of outbreaks in 18 countries and six different languages. We observed an early strong upsurge of anxiety-related terms in all countries, which was related to the growth in cases and increases in the stringency of governmental measures. Anxiety expression gradually relaxed once stringent measures were in place, possibly indicating that people were reassured. Sadness terms rose and anger terms decreased with or after an increase in the stringency of measures and remained stable as long as measures were in place. Positive emotion words only decreased slightly and briefly in a few countries. Our results reveal some of the most enduring changes in emotional expression observed in long periods of social media data. Such sustained emotional expression could indicate that interactions between users led to the emergence of collective emotions. Words that frequently occurred in tweets suggest a shift in topics of conversation across all emotions, from political ones in 2019, to pandemic related issues during the outbreak, including everyday life changes, other people, and health. This kind of time-sensitive analyses of large-scale samples of emotional expression have the potential to inform risk communication. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Epidemic Diffusion Network of Spain: A Mobility Model to Characterize the Transmission Routes of Disease

Human mobility drives the geographical diffusion of infectious diseases at different scales, but few studies focus on mobility itself. Using publicly available data from Spain, we define a Mobility Matrix that captures constant flows between provinces by using a distance-like measure of effective distance to build a network model with the 52 provinces and 135 relevant edges. Madrid, Valladolid and Araba/Álaba are the most relevant nodes in terms of degree and strength. The shortest routes (most likely path between two points) between all provinces are calculated. A total of 7 mobility communities were found with a modularity of 63%, and a relationship was established with a cumulative incidence of COVID-19 in 14 days (CI14) during the study period. In conclusion, mobility patterns in Spain are governed by a small number of high-flow connections that remain constant in time and seem unaffected by seasonality or restrictions. Most of the travels happen within communities that do not completely represent political borders, and a wave-like spreading pattern with occasional long-distance jumps (small-world properties) can be identified. This information can be incorporated into preparedness and response plans targeting locations that are at risk of contagion preventively, underscoring the importance of coordination between administrations when addressing health emergencies.

Deep habits and travel resilience after COVID-19

This research examines how deep travel habits in the form of habit formation and reduced substitutability between tourism travel and other leisure goods impact travel resilience after COVID-19. Using microdata for almost 3000 tourists in Andalusia (Spain), we relate post-pandemic outbreak tourism participation to pre-pandemic travelling intensity and whether taking a vacation is considered a priority good. In doing so, we control for standard sociodemographic characteristics and province fixed effects. Our results clearly show that the probability of continuing travelling during the summer of 2020 is positively associated with pre-pandemic travel intensity and tourism being considered a priority leisure activity. Travel resilience is found to be strongly associated with income, education level and the tenure of a second residence.

The impact of COVID-19 on tourists' length of stay and daily expenditures

This study evaluates the effect of the COVID-19 pandemic on tourists' length of stay and daily expenditures at a destination. The paper compares detailed microdata for visitors to a Northern Spanish region in the summer periods of 2019 (pre-pandemic) and 2020 (after the pandemic outbreak). We estimate the pandemic-induced impacts on the length of stay and expenditures per person for several categories using regression adjustment, inverse probability weighting regression and propensity score matching. We find clear evidence of a drop in the length of stay of around 1.26 nights, representing a 23.8% decline. We also show that, although total expenditures per person and day have remained constant, there has been a change in the allocations for categories in the tourism budget.

Epidemic Diffusion Network of Spain: A Mobility Model to Characterize the Transmission Routes of Disease.

Human mobility drives the geographical diffusion of infectious diseases at different scales, but few studies focus on mobility itself. Using publicly available data from Spain, we define a Mobility Matrix that captures constant flows between provinces by using a distance-like measure of effective distance to build a network model with the 52 provinces and 135 relevant edges. Madrid, Valladolid and Araba/Álaba are the most relevant nodes in terms of degree and strength. The shortest routes (most likely path between two points) between all provinces are calculated. A total of 7 mobility communities were found with a modularity of 63%, and a relationship was established with a cumulative incidence of COVID-19 in 14 days (CI14) during the study period. In conclusion, mobility patterns in Spain are governed by a small number of high-flow connections that remain constant in time and seem unaffected by seasonality or restrictions. Most of the travels happen within communities that do not completely represent political borders, and a wave-like spreading pattern with occasional long-distance jumps (small-world properties) can be identified. This information can be incorporated into preparedness and response plans targeting locations that are at risk of contagion preventively, underscoring the importance of coordination between administrations when addressing health emergencies.

Evolution of Risk Behaviors, Sexually Transmitted Infections and PrEP Care Continuum in a Hospital-Based PrEP Program in Barcelona, Spain: A Descriptive Study of the First 2 Years' Experience.

INTRODUCTION: Pre-exposure prophylaxis (PrEP) is effective for HIV prevention, but the PrEP care continuum also involves improving PrEP awareness, uptake, adherence, and retention in care. Users' awareness is often compromised because of vulnerability factors and risk behaviors, such as chemsex practice or specific substance use, which could lead to risk compensation. Correct adherence and retention in care are essential to achieve the full effectiveness of PrEP. This study describes changes in users' risk behaviors and sexually transmitted infections (STIs), as well also PrEP care continuum details. METHODS: This was a descriptive single-center retrospective study including adults at high HIV risk screened between November 2019 and June 2021 in the PrEP program of our hospital. Demographic, behavioral, STI, adherence, and retention in care variables were assessed. Data were collected from medical records and self-report questionnaires. RESULTS: A total of 295 people were included, 94% men and 5% transgender women, with a mean age of 34 years (SD 10) and 10% sex workers. At baseline, 55% disclosed chemsex practice and 3% slamming. During follow-up, condom use for anal intercourse decreased from 41% to 13% (p ≤ 0.0001) and one HIV infection was detected; other risk behaviors and STIs remained stable. Chemsex, group sex, fluid exchange, and condomless anal intercourse were related to STI risk. Adherence was correct in 80% of users, and retention in care was 57%. Discontinuations and loss to follow-up were high, mainly affecting transgender women, sex workers, and people practicing fisting. CONCLUSION: PrEP program implementation in our hospital was adequate, since it allowed, in a population at high HIV risk, overall users' risk behaviors and STIs to remain stable, with only one HIV diagnosis during the follow-up. We should target specific strategies to improve adherence and retention in care, as vulnerable subgroups at higher risk of loss to follow-up are identified.

Legal regulation of ventilation rates in homes in Europe 2010-2022: Evolution and comparison study regarding Covid-19 recommendations.

The airborne transmission of SARS-CoV-2, the virus that causes Covid-19 disease, has been recognized as an essential route of contagion, so adequate ventilation is vital indoors. For this reason, the research goal focuses on carrying out the study and evolutionary and comparison analysis of the regulation of ventilation rates in dwellings in Europe (2010-2022) and on determining whether modifications are necessary for the said regulation based on the recommendations of competent international organizations. To do this, the methodology followed initially starts from the study carried out in 2010 by Christine Dimitroulopoulou, in which the existing regulation in various European countries regarding ventilation in dwellings was studied. Once this study has been analysed, it continues to update and compare the regulation of the different European countries cited in the said work, detecting during the process if a modification is necessary based on the recommendations indicated by international organizations such as the WHO or ECDC. The results and conclusions indicate that few countries have significantly changed their ventilation rates. Although the existing ones may be admissible, requiring controlled ventilation in the different regulations would be convenient.

Investigating the two-way relationship between mobility flows and COVID-19 cases.

Following a pandemic disease outbreak, people travel to areas with low infection risk, but at the same time the epidemiological situation worsens as mobility flows to those areas increase. These feedback effects from epidemiological conditions to inflows and from inflows to subsequent infections are underexplored to date. This study investigates the two-way relationship between mobility flows and COVID-19 cases in a context of unrestricted mobility without COVID-19 vaccines. To this end, we merge data on COVID-19 cases in Spain during the summer of 2020 at the province level with mobility records based on mobile position tracking. Using a control function approach, we find that a 1% increase in arrivals translates into a 3.5% increase in cases in the following week and 5.6% ten days later. A simulation exercise shows the cases would have dropped by around 64% if the Second State of Alarm had been implemented earlier.

Plasma biomarkers associated with survival and thrombosis in hospitalized COVID-19 patients.

Severe coronavirus disease-19 (COVID-19) has been associated with fibrin-mediated hypercoagulability and thromboembolic complications. To evaluate potential biomarkers of coagulopathy and disease severity in COVID-19, we measured plasma levels of eight biomarkers potentially associated with coagulation, fibrinolysis, and platelet function in 43 controls and 63 COVID-19 patients, including 47 patients admitted to the intensive care unit (ICU) and 16 non-ICU patients. COVID-19 patients showed significantly elevated levels of fibrinogen, tissue plasminogen activator (t-PA), and its inhibitor plasminogen activation inhibitor 1 (PAI-1), as well as ST2 (the receptor for interleukin-33) and von Willebrand factor (vWF) compared to the control group. We found that higher levels of t-PA, ST2, and vWF at the time of admission were associated with lower survival rates, and that thrombotic events were more frequent in patients with initial higher levels of vWF. These results support a predictive role of specific biomarkers such as t-PA and vWF in the pathophysiology of COVID-19. The data provide support for the case that hypercoagulability in COVID-19 is fibrin-mediated, but also highlights the important role that vWF may play in the genesis of thromboses in the pathophysiology of COVID-19. Interventions designed to enhance fibrinolysis might prove to be useful adjuncts in the treatment of coagulopathy in a subset of COVID-19 patients.

Identification of the first COVID-19 infections in the US using a retrospective analysis (REMEDID).

Accurate detection of early COVID-19 cases is crucial to reduce infections and deaths, however, it remains a challenge. Here, we used the results from a seroprevalence study in 50 US states to apply our Retrospective Methodology to Estimate Daily Infections from Deaths (REMEDID) with the aim of analyzing the initial spread of SARS-CoV-2 infections across the US. Our analysis revealed that the virus likely entered the country through California on December 28, 2019, which corresponds to 16 days prior to the officially recognized entry date established by the Centers of Disease Control and Prevention. Furthermore, the REMEDID algorithm provides evidence that SARS-CoV-2 entered, on average, a month earlier than previously reflected in official data for each US state. Collectively, our mathematical modeling provides more accurate estimates of the initial COVID-19 cases in the US, and has the ability to be extrapolated to other countries and used to retrospectively track the progress of the pandemic. The use of approaches such as REMEDID are highly recommended to better understand the early stages of an outbreak, which will enable health authorities to improve mitigation and preventive measures in the future.

Caveats on COVID-19 herd immunity threshold: the Spain case.

After a year of living with the COVID-19 pandemic and its associated consequences, hope looms on the horizon thanks to vaccines. The question is what percentage of the population needs to be immune to reach herd immunity, that is to avoid future outbreaks. The answer depends on the basic reproductive number, R0, a key epidemiological parameter measuring the transmission capacity of a disease. In addition to the virus itself, R0 also depends on the characteristics of the population and their environment. Additionally, the estimate of R0 depends on the methodology used, the accuracy of data and the generation time distribution. This study aims to reflect on the difficulties surrounding R0 estimation, and provides Spain with a threshold for herd immunity, for which we considered the different combinations of all the factors that affect the R0 of the Spanish population. Estimates of R0 range from 1.39 to 3.10 for the ancestral SARS-CoV-2 variant, with the largest differences produced by the method chosen to estimate R0. With these values, the herd immunity threshold (HIT) ranges from 28.1 to 67.7%, which would have made 70% a realistic upper bound for Spain. However, the imposition of the delta variant (B.1.617.2 lineage) in late summer 2021 may have expanded the range of R0 to 4.02-8.96 and pushed the upper bound of the HIT to 90%.

Nonalcoholic Fatty Liver Disease and Associated Risk Factors in a Community-Based Sample of Mexican-Origin Adults.

The incidence of nonalcoholic fatty liver disease (NAFLD) is highest among Mexican-origin (MO) adults. Few studies have estimated the prevalence of NAFLD in this subpopulation, particularly by sex and age. We assessed the prevalence of NAFLD in a community sample of MO adults residing in a border region of southern Arizona and determined risk factors associated with NAFLD. A total of 307 MO adults (n = 194 women; n = 113 men) with overweight or obesity completed an in-person study visit, including vibration-controlled transient elastography (FibroScan) for the assessment of NAFLD status. A continuous attenuation parameter score of ≥288 dB/m (≥5% hepatic steatosis) indicated NAFLD status. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for NAFLD. We identified 155 participants (50%) with NAFLD, including 52% of women and 48% of men; there were no sex differences in steatosis (men, 287.8 dB/m; women, 288.4 dB/m). Sex, age, patatin-like phospholipase domain containing 3 (PNPLA3) risk allele carrier status, comorbidities, and cultural and behavioral variables were not associated with NAFLD status. There was some evidence for effect modification of body mass index (BMI) by sex (Pinteraction  = 0.08). The estimated OR for an increase in BMI of 5 kg/m2 was 3.36 (95% CI, 1.90, 5.91) for men and 1.92 (95% CI, 1.40, 2.64) for women. In post hoc analyses treating steatosis as a continuous variable in a linear regression, significant effect modification was found for BMI by sex (Pinteraction  = 0.03), age (P = 0.05), and PNPLA3 risk allele carrier status (P = 0.02). Conclusion: Lifestyle interventions to reduce body weight, with consideration of age and genetic risk status, are needed to stem the higher rates of NAFLD observed for MO populations.

Assessing the effect of non-pharmaceutical interventions on COVID-19 transmission in Spain, 30 August 2020 to 31 January 2021.

BackgroundAfter a national lockdown during the first wave of the COVID-19 pandemic in Spain, regional governments implemented different non-pharmaceutical interventions (NPIs) during the second wave.AimTo analyse which implemented NPIs significantly impacted effective reproduction number (Rt) in seven Spanish provinces during 30 August 2020-31 January 2021.MethodsWe coded each NPI and levels of stringency with a 'severity index' (SI) and computed a global SI (mean of SIs per six included interventions). We performed a Bayesian change point analysis on the Rt curve of each province to identify possible associations with global SI variations. We fitted and compared several generalised additive models using multimodel inference, to quantify the statistical effect on Rt of the global SI (stringency) and the individual SIs (separate effect of NPIs).ResultsThe global SI had a significant lowering effect on the Rt (mean: 0.16 ± 0.05 units for full stringency). Mandatory closing times for non-essential businesses, limited gatherings, and restricted outdoors seating capacities (negative) as well as curfews (positive) were the only NPIs with a significant effect. Regional mobility restrictions and limited indoors seating capacity showed no effect. Our results were consistent with a 1- to 3-week-delayed Rt as a response variable.ConclusionWhile response measures implemented during the second COVID-19 wave contributed substantially to a decreased reproduction number, the effectiveness of measures varied considerably. Our findings should be considered for future interventions, as social and economic consequences could be minimised by considering only measures proven effective.

Thromboembolic prevention and anticoagulant therapy during the COVID-19 pandemic: updated clinical guidance from the anticoagulation forum.

Thromboembolism is a common and deadly consequence of COVID-19 infection for hospitalized patients. Based on clinical evidence pre-dating the COVID-19 pandemic and early observational reports, expert consensus and guidance documents have strongly encouraged the use of prophylactic anticoagulation for patients hospitalized for COVID-19 infection. More recently, multiple clinical trials and larger observational studies have provided evidence for tailoring the approach to thromboprophylaxis for patients with COVID-19. This document provides updated guidance for the use of anticoagulant therapies in patients with COVID-19 from the Anticoagulation Forum, the leading North American organization of anticoagulation providers. We discuss ambulatory, in-hospital, and post-hospital thromboprophylaxis strategies as well as provide guidance for patients with thrombotic conditions who are considering COVID-19 vaccination.

Assessment of the effectiveness of Omicron transmission mitigation strategies for European universities using an agent-based network model.

BACKGROUND: Returning universities to full on-campus operations while the COVID-19 pandemic is ongoing has been a controversial discussion in many countries. The risk of large outbreaks in dense course settings is contrasted by the benefits of in-person teaching. Transmission risk depends on a range of parameters, such as vaccination coverage and efficacy, number of contacts and adoption of non-pharmaceutical intervention measures (NPIs). Due to the generalised academic freedom in Europe, many universities are asked to autonomously decide on and implement intervention measures and regulate on-campus operations. In the context of rapidly changing vaccination coverage and parameters of the virus, universities often lack sufficient scientific insight to base these decisions on. METHODS: To address this problem, we analyse a calibrated, data-driven agent-based simulation of transmission dynamics of 13,284 students and 1,482 faculty members in a medium-sized European university. We use a co-location network reconstructed from student enrollment data and calibrate transmission risk based on outbreak size distributions in education institutions. We focus on actionable interventions that are part of the already existing decision-making process of universities to provide guidance for concrete policy decisions. RESULTS: Here we show that, with the Omicron variant of the SARS-CoV-2 virus, even a reduction to 25% occupancy and universal mask mandates are not enough to prevent large outbreaks given the vaccination coverage of about 85% recently reported for students in Austria. CONCLUSIONS: Our results show that controlling the spread of the virus with available vaccines in combination with NPIs is not feasible in the university setting if presence of students and faculty on campus is required.

Early Use of Sarilumab in Patients Hospitalized with COVID-19 Pneumonia and Features of Systemic Inflammation: the SARICOR Randomized Clinical Trial.

The objective of this study was to investigate the efficacy and safety of early treatment with sarilumab, added to standard of care (SOC), in hospitalized adults with COVID-19. Methods included phase II, open-label, randomized, controlled clinical trial of hospitalized patients with COVID-19 pneumonia and interleukin (IL)-6 levels ≥ 40 pg/mL and/or d-dimer > 1,500 ng/mL. Participants were randomized (1:1:1) to receive SOC (control group), SOC plus a single subcutaneous dose of sarilumab 200 mg (sarilumab-200 group), or SOC plus a single subcutaneous dose of sarilumab 400 mg (sarilumab-400 group). The primary outcome variable was the development of acute respiratory distress syndrome (ARDS) requiring high-flow nasal oxygenation (HFNO), non-invasive mechanical ventilation (NIMV) or invasive mechanical ventilation (IMV) at day 28. One-hundred and 15 participants (control group, n = 39; sarilumab-200, n = 37; sarilumab-400, n = 39) were included. At randomization, 104 (90%) patients had supplemental oxygen and 103 (90%) received corticosteroids. Eleven (28%) patients in the control group, 10 (27%) in sarilumab-200, and five (13%) in sarilumab-400 developed the primary outcome (hazard ratio [95% CI] of sarilumab-400 vs control group: 0.41 [0.14, 1.18]; P = 0.09). Seven (6%) patients died: three in the control group and four in sarilumab-200. There were no deaths in sarilumab-400 (P = 0.079, log-rank test for comparisons with the control group). In patients recently hospitalized with COVID-19 pneumonia and features of systemic inflammation, early IL-6 blockade with a single dose of sarilumab 400 mg was safe and associated with a trend for better outcomes. (This study has been registered at ClinicalTrials.gov under identifier NCT04357860.).

In high-risk inpatients with COVID-19, therapeutic- vs. standard-dose heparin reduced thromboembolism or death at 30 d.

SOURCE CITATION: Spyropoulos AC, Goldin M, Giannis D, et al. Efficacy and safety of therapeutic-dose heparin vs standard prophylactic or intermediate-dose heparins for thromboprophylaxis in high-risk hospitalized patients with COVID-19: the HEP-COVID randomized clinical trial. JAMA Intern Med. 2021;181:1612-20. 34617959.