Impact of Very Short-Lived Substances on Stratospheric Bromine Loading

Recent studies have shown the importance of very short-lived substances (VSLS) for the abundance of stratospheric bromine. In this work, the transport of bromine VSLS into the stratosphere is investigated with a three-dimensional chemistry transport model. The novelty of this approach is the explicit treatment of convective transport in a purely isentropic model, a key prerequisite for the realistic reproduction of the complex interplay of horizontal advection, local deep convection and large-scale diabatic heating in the tropical tropopause layer. Comparisons with observations show that the model is generally able to produce realistic distributions of the two major bromine VSLS, bromoform (CHBr3) and dibromomethane (CH2Br2). In addition, an analysis of the regional transport efficiency suggests that the Western Pacific is the most important source area for VSLS into the stratosphere; approximately 50% of the total amount of bromine VSLS in the TTL is contributed by this region. Another important question is how dehydration in the tropical tropopause impacts on stratospheric bromine loading. An idealized modeling approach assuming total solubility for inorganic bromine predicts that about 60% of bromine originated from VSLS is able to reach the stratosphere, which is consistent with earlier modeling approaches that use a comparable simple dehydration mechanism. However, when applying a more complete chemistry scheme the model results show that virtually the entire amount of bromine contributed by VSLS enters the stratosphere, rendering the impact of dehydration and scavenging on inorganic bromine insignificant in the TTL. This discrepancy is mainly caused by the low fraction of actually soluble inorganic bromine, the small available particle surface area density that restricts adsorption and finally heterogeneous reactions which are able to release adsorbed species into gas phase. Long-term calculations of VSLS injection into the stratosphere reveal a robust correlation between sea surface temperature, convective activity and the amount of short-lived source gases in the TTL, which becomes especially clear during the perturbations induced by El Nino seasons. Finally, the impact of additional bromine originated from VSLS on stratospheric ozone depletion is analyzed. The model predicts that for 5 parts per trillion by volume (pptv) of bromine contributed by VSLS on average about 1.3% of global total column ozone is destroyed

Mental health of individuals infected with SARS-CoV-2 during mandated isolation and compliance with recommendations-A population-based cohort study

BACKGROUND: Isolation is an indispensable measure to contain the SARS-CoV-2 virus, but it may have a negative impact on mental health and overall wellbeing. Evidence on the isolation experience, facilitating and complicating factors is needed to mitigate negative effects. METHODS AND FINDINGS: This observational, population-based cohort study enrolled 1547 adults from the general population with SARS-CoV-2 infection reported to authorities between 27 February 2020 and 19 January 2021 in Zurich, Switzerland. We assessed the proportion of individuals reporting symptoms of depression and anxiety before, during and after isolation (by DASS-21), and queried worries, positive experiences, and difficulties. We analyzed the association of these outcomes with socio-demographics using ordinal regression. Additionally, we report free-text statements by participants to capture most important aspects of isolation. The proportion of participants affected by depression or anxiety increased during isolation from 10·0% to 17·1% and 9·1% to 17·6%, respectively. Ordinal regression showed that taking care of children increased the difficulty of isolation (OR 2·10, CI 1·43-3·08) and risk of non-compliance (OR 1·63, CI 1·05-2·53), especially in younger participants. A facilitating factor that individuals commonly expressed was receiving more support during isolation. CONCLUSION: Isolation due to SARS-CoV-2 presents a mental burden, especially for younger individuals and those taking care of children. Public health authorities need to train personnel and draw from community-based resources to provide targeted support, information, and guidance to individuals during isolation. Such efforts could alleviate the negative impact isolation has on the mental and physical health of individuals and ensure compliance of the population with recommendations

Natural course of post COVID-19 condition and implications for trial design and outcome selection: A population-based longitudinal cohort study

Background Evidence from population-based studies on the longer-term natural course of post COVID-19 condition is limited, but crucial for informing patients and healthcare providers and for effectively designing clinical trials. Objectives To evaluate longer-term symptoms and health outcomes within a cohort of SARS-CoV-2 infected individuals. Design Population-based, longitudinal cohort. Setting General population, Canton of Zurich, Switzerland. Patients 1543 adults with confirmed SARS-CoV-2 infection and 628 adults without infection. Measurements Changes in self-reported health status over time, factors associated with persistence of non-recovery, and prevalence and excess risk of symptoms at 6 and 12 months post-infection compared to non-infected individuals. Results 25% of SARS-CoV-2 infected individuals did not recover by 6 months. Of those, 67% and 58% also did not recover at 12 and 18 months after infection, respectively. Hospitalization for acute COVID-19, pre-existing fatigue and pain or discomfort, and presence of specific systemic, cardiovascular, or musculoskeletal symptoms at 6 months were associated with persistent non-recovery. Symptom prevalence was higher among infected individuals compared to non-infected individuals at 6 months (adjusted risk difference (aRD)=17%) and 12 months (aRD=20%). aRDs for individual symptoms ranged from 2% to 12%, with the highest excess risks observed for altered taste or smell, post-exertional malaise, fatigue, and reduced concentration and memory. Limitations We relied on self-reported assessments and did not assess the effects of vaccination or infection with emerging variants of concern. Conclusion These findings emphasize the need for effective interventions to reduce the burden of post COVID-19 condition. They further demonstrate the importance of using multiple outcome measures and of considering the expected rates of natural recovery and heterogenous patient trajectories in the design and interpretation of clinical trials

Individual-Level Evaluation of the Exposure Notification Cascade in the SwissCovid Digital Proximity Tracing App: Observational Study

Background: Digital proximity tracing (DPT) aims to complement manual contact tracing (MCT) in identifying exposed contacts and preventing further transmission of SARS-CoV-2 in the population. Although several DPT apps, including SwissCovid, have shown to have promising effects on mitigating the pandemic, several challenges have impeded them from fully achieving the desired results. A key question now relates to how the effectiveness of DPT can be improved, which requires a better understanding of factors influencing its processes. Objective: In this study, we aim to provide a detailed examination of the exposure notification (EN) cascade and to evaluate potential contextual influences for successful receipt of an EN and subsequent actions taken by cases and contacts in different exposure settings. Methods: We used data from 285 pairs of SARS-CoV-2-infected cases and their contacts within an observational cohort study of cases and contacts identified by MCT and enrolled between August 6, 2020, and January 17, 2021, in the canton of Zurich, Switzerland. We surveyed participants with electronic questionnaires. Data were summarized descriptively and stratified by exposure setting. Results: We found that only 79 (58.5%) of 135 contacts using the SwissCovid app whose corresponding cases reported to have triggered the EN also received one. Of these, 18 (22.8%) received the EN before MCT. Compared to those receiving an EN after MCT (61/79, 77.2%), we observed that a higher proportion of contacts receiving an EN before MCT were exposed in nonhousehold settings (11/18, 61.1%, vs 34/61, 55.7%) and their corresponding cases had more frequently reported mild-to-moderate symptoms (14/18, 77.8%, vs 42/61, 68.9%). Of the 18 contacts receiving an EN before MCT, 14 (77.8%) took recommended measures: 12 (66.7%) were tested for SARS-CoV-2, and 7 (38.9%) called the SwissCovid Infoline. In nonhousehold settings, the proportion of contacts taking preventive actions after receiving an EN was higher compared to same-household settings (82%, vs 67%). In addition, 1 (9%) of 11 ENs received in the nonhousehold setting before MCT led to the identification of a SARS-CoV-2-infected case by prompting the contact to get tested. This corresponds to 1 in 85 exposures of a contact to a case in a nonhousehold setting, in which both were app users and the case triggered the EN. Conclusions: Our descriptive evaluation of the DPT notification cascade provides further evidence that DPT is an important complementary tool in pandemic mitigation, especially in nonhousehold exposure settings. However, the effect of DPT apps can only be exerted if code generation processes are efficient and exposed contacts are willing to undertake preventive actions. This highlights the need to focus efforts on keeping barriers to efficient code generation as low as possible and promoting not only app adoption but also compliance with the recommended measures upon an EN. Trial registration: International Standard Randomised Controlled Trial Number Registry 14990068; https://doi.org/10.1186/ISRCTN14990068. Keywords: COVID-19; SARS-CoV-2; SwissCovid; app; contact tracing; digital proximity tracing; epidemiology; evaluation; exposure; mHealth; mobile app; notification; observational; public health; surveillance; tracking

Heterogenous humoral and cellular immune responses with distinct trajectories post-SARS-CoV-2 infection in a population-based cohort

To better understand the development of SARS-CoV-2-specific immunity over time, a detailed evaluation of humoral and cellular responses is required. Here, we characterize anti-Spike (S) IgA and IgG in a representative population-based cohort of 431 SARS-CoV-2-infected individuals up to 217 days after diagnosis, demonstrating that 85% develop and maintain anti-S responses. In a subsample of 64 participants, we further assess anti-Nucleocapsid (N) IgG, neutralizing antibody activity, and T cell responses to Membrane (M), N, and S proteins. In contrast to S-specific antibody responses, anti-N IgG levels decline substantially over time and neutralizing activity toward Delta and Omicron variants is low to non-existent within just weeks of Wildtype SARS-CoV-2 infection. Virus-specific T cells are detectable in most participants, albeit more variable than antibody responses. Cluster analyses of the co-evolution of antibody and T cell responses within individuals identify five distinct trajectories characterized by specific immune patterns and clinical factors. These findings demonstrate the relevant heterogeneity in humoral and cellular immunity to SARS-CoV-2 while also identifying consistent patterns where antibody and T cell responses may work in a compensatory manner to provide protection

Einfluss kurzlebiger Substanzen auf den stratosphärischen Bromgehalt

Recent studies have shown the importance of very short-lived substances (VSLS) for the abundance of stratospheric bromine. In this work, the transport of bromine VSLS into the stratosphere is investigated with a three-dimensional chemistry transport model. The novelty of this approach is the explicit treatment of convective transport in a purely isentropic model, a key prerequisite for the realistic reproduction of the complex interplay of horizontal advection, local deep convection and large-scale diabatic heating in the tropical tropopause layer. Comparisons with observations show that the model is generally able to produce realistic distributions of the two major bromine VSLS, bromoform (CHBr3) and dibromomethane (CH2Br2). In addition, an analysis of the regional transport efficiency suggests that the Western Pacific is the most important source area for VSLS into the stratosphere; approximately 50% of the total amount of bromine VSLS in the TTL is contributed by this region. Another important question is how dehydration in the tropical tropopause impacts on stratospheric bromine loading. An idealized modeling approach assuming total solubility for inorganic bromine predicts that about 60% of bromine originated from VSLS is able to reach the stratosphere, which is consistent with earlier modeling approaches that use a comparable simple dehydration mechanism. However, when applying a more complete chemistry scheme the model results show that virtually the entire amount of bromine contributed by VSLS enters the stratosphere, rendering the impact of dehydration and scavenging on inorganic bromine insignificant in the TTL. This discrepancy is mainly caused by the low fraction of actually soluble inorganic bromine, the small available particle surface area density that restricts adsorption and finally heterogeneous reactions which are able to release adsorbed species into gas phase. Long-term calculations of VSLS injection into the stratosphere reveal a robust correlation between sea surface temperature, convective activity and the amount of short-lived source gases in the TTL, which becomes especially clear during the perturbations induced by El Nino seasons. Finally, the impact of additional bromine originated from VSLS on stratospheric ozone depletion is analyzed. The model predicts that for 5 parts per trillion by volume (pptv) of bromine contributed by VSLS on average about 1.3% of global total column ozone is destroyed

Adherence and Association of Digital Proximity Tracing App Notifications With Earlier Time to Quarantine: Results From the Zurich SARS-CoV-2 Cohort Study

Objectives: We aimed to evaluate the effectiveness of the SwissCovid digital proximity tracing (DPT) app in notifying exposed individuals and prompting them to quarantine earlier compared to individuals notified only by manual contact tracing (MCT).Methods: A population-based sample of cases and close contacts from the Zurich SARS-CoV-2 Cohort was surveyed regarding SwissCovid app use and SARS-CoV-2 exposure. We descriptively analyzed app adherence and effectiveness, and evaluated its effects on the time between exposure and quarantine among contacts using stratified multivariable time-to-event analyses.Results: We included 393 SARS-CoV-2 infected cases and 261 close contacts. 62% of cases reported using SwissCovid and among those, 88% received and uploaded a notification code. 71% of close contacts were app users, of which 38% received a warning. Non-household contacts notified by SwissCovid started quarantine 1 day earlier and were more likely to quarantine earlier than those not warned by the app (HR 1.53, 95% CI 1.15–2.03).Conclusion: These findings provide evidence that DPT may reach exposed contacts faster than MCT, with earlier quarantine and potential interruption of SARS-CoV-2 transmission chains

Burden of post-COVID-19 syndrome and implications for healthcare service planning: A population-based cohort study

Background Longer-term consequences after SARS-CoV-2 infection are becoming an important burden to societies and healthcare systems. Data on post-COVID-19 syndrome in the general population are required for the timely planning of healthcare services and resources. The objective of this study was to assess the prevalence of impaired health status and physical and mental health symptoms among individuals at least six months after SARS-CoV-2 infection, and to characterize their healthcare utilization. Methods This population-based prospective cohort study (Zurich SARS-CoV-2 Cohort) enrolled 431 adults from the general population with polymerase chain reaction-confirmed SARS-CoV-2 infection reported to health authorities between 27 February 2020 and 05 August 2020 in the Canton of Zurich, Switzerland. We evaluated the proportion of individuals reporting not to have fully recovered since SARS-CoV-2 infection, and the proportion reporting fatigue (Fatigue Assessment Scale), dyspnea (mMRC dyspnea scale) or depression (DASS-21) at six to eight months after diagnosis. Furthermore, the proportion of individuals with at least one healthcare contact after their acute illness was evaluated. Multivariable logistic regression models were used to assess factors associated with these main outcomes. Results Symptoms were present in 385 (89%) participants at diagnosis and 81 (19%) were initially hospitalized. At six to eight months, 111 (26%) reported not having fully recovered. 233 (55%) participants reported symptoms of fatigue, 96 (25%) had at least grade 1 dyspnea, and 111 (26%) had DASS-21 scores indicating symptoms of depression. 170 (40%) participants reported at least one general practitioner visit related to COVID-19 after acute illness, and 10% (8/81) of initially hospitalized individuals were rehospitalized. Individuals that have not fully recovered or suffer from fatigue, dyspnea or depression were more likely to have further healthcare contacts. However, a third of individuals (37/111) that have not fully recovered did not seek further care. Conclusions In this population-based study, a relevant proportion of participants suffered from longer-term consequences after SARS-CoV-2 infection. With millions infected across the world, our findings emphasize the need for the timely planning of resources and patient-centered services for post-COVID-19 care

Recovery and symptom trajectories up to two years after SARS-CoV-2 infection: population based, longitudinal cohort study.

ObjectiveTo evaluate longer term symptoms and health outcomes associated with post-covid-19 condition within a cohort of individuals with a SARS-CoV-2 infection.DesignPopulation based, longitudinal cohort.SettingGeneral population of canton of Zurich, Switzerland.Participants1106 adults with a confirmed SARS-CoV-2 infection who were not vaccinated before infection and 628 adults who did not have an infection.Main outcome measuresTrajectories of self-reported health status and covid-19 related symptoms between months six, 12, 18, and 24 after infection and excess risk of symptoms at six months after infection compared with individuals who had no infection.Results22.9% (95% confidence interval 20.4% to 25.6%) of individuals infected with SARS-CoV-2 did not fully recover by six months. The proportion of individuals who had an infection who reported not having recovered decreased to 18.5% (16.2% to 21.1%) at 12 months and 17.2% (14.0% to 20.8%) at 24 months after infection. When assessing changes in self-reported health status, most participants had continued recovery (68.4% (63.8% to 72.6%)) or had an overall improvement (13.5% (10.6% to 17.2%)) over time. Yet, 5.2% (3.5% to 7.7%) had a worsening in health status and 4.4% (2.9% to 6.7%) had alternating periods of recovery and health impairment. The point prevalence and severity of covid-19 related symptoms also decreased over time, with 18.1% (14.8% to 21.9%) reporting symptoms at 24 months. 8.9% (6.5% to 11.2%) of participants reported symptoms at all four follow-up time points, while in 12.5% (9.8% to 15.9%) symptoms were alternatingly absent and present. Symptom prevalence was higher among individuals who were infected compared with those who were not at six months (adjusted risk difference 17.0% (11.5% to 22.4%)). Excess risk (adjusted risk difference) for individual symptoms among those infected ranged from 2% to 10%, with the highest excess risks observed for altered taste or smell (9.8% (7.7% to 11.8%)), post-exertional malaise (9.4% (6.1% to 12.7%)), fatigue (5.4% (1.2% to 9.5%)), dyspnoea (7.8% (5.2% to 10.4%)), and reduced concentration (8.3% (6.0% to 10.7%)) and memory (5.7% (3.5% to 7.9%)).ConclusionsUp to 18% of individuals who were not vaccinated before infection had post-covid-19 condition up to two years after infection, with evidence of excess symptom risk compared with controls. Effective interventions are needed to reduce the burden of post-covid-19 condition. Use of multiple outcome measures and consideration of the expected rates of recovery and heterogeneity in symptom trajectories are important in the design and interpretation of clinical trials.RegistrationsISRCTN18181860,

Mental Health of Individuals Infected With SARS-CoV-2 During Mandated Isolation and Compliance With Recommendations - A Population-Based Cohort Study

Background: Isolation is an indispensable measure to contain the SARS-CoV-2 virus, but it may have a negative impact on mental health. Evidence on the isolation experience, facilitating and complicating factors is needed to mitigate negative effects. Methods: This population-based prospective cohort study enrolled 1547 adults from the general population with SARS-CoV-2 infection reported to authorities between 27 February 2020 and 19 January 2021 in Zurich, Switzerland. We assessed the proportion of individuals reporting symptoms of depression and anxiety before, during and after isolation (by DASS-21), and queried worries, positive experiences, and difficulties. We analyzed the association of these outcomes with socio-demographics using ordinal regression. Additionally, we report free-text statements by participants to capture important aspects of isolation. Findings: The proportion of participants affected by depression or anxiety increased during isolation from 10·0% to 17·1% and 9·1% to 17·6%, respectively. Ordinal regression showed that taking care of children increased the difficulty of isolation (OR 2·10, CI 1·43 – 3·08) and risk of non-compliance (OR 1·63, CI 1·05 – 2·53), especially in younger participants. A facilitating factor that individuals commonly expressed was receiving more support during isolation. Interpretation: Isolation due to SARS-CoV-2presents a mental burden , especially for younger individuals and those taking care of children. Public health authorities need to train personnel and draw from community-based resources to provide targeted support, information, and guidance to individuals during isolation. Such efforts could alleviate the negative impact isolation has on the mental and physical health of individuals and ensure compliance of the population with recommendations. Funding Information: The Zurich SARS-CoV-2 Cohort study is funded through the Health Directorate of the Canton of Zurich and the Pandemic Fund of the University of Zurich. The study is also part of the Corona Immunitas research program, coordinated by the Swiss School of Public Health (SSPH+) and funded through SSPH+ fundraising, including funding by the Swiss Federal Office of Public Health, the Cantons of Switzerland (Basel, Vaud, and Zurich), private funders (ethical guidelines for funding stated by SSPH+ were respected) and institutional funds of the participating universities. HEA was also supported by an SNSF Early Postdoc. Mobility Fellowship. TB received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 801076, through the SSPH+Global PhD Fellowship Program in Public Health Sciences (GlobalP3HS) of the Swiss School of Public Health. Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: We obtained electronic written consent from all participants. The study protocol was approved by the ethics committee of the Canton of Zurich (BASEC 2020-01739)