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BackgroundEvidence from population-based studies on the impact of post COVID-19 condition (PCC) on ability to work is limited but critical due to its high prevalence among individuals of working-age.ObjectiveTo evaluate the association between PCC, work ability, and occupational changes.DesignPopulation-based, longitudinal cohort.SettingGeneral population, Canton of Zurich, Switzerland.Participants672 adults of working-age with SARS-CoV-2 infection.MeasurementsCurrent work ability, work ability related to physical and mental demands, and estimated future work ability in 2 years (assessed using Work Ability Index), as well as PCC-related occupational changes at one year after infection.ResultsThere was very strong evidence that current work ability scores were 0.62 (95% confidence interval (CI) 0.30 to 0.95) points lower among those with PCC compared to those without. Similarly, there was very strong evidence for lower odds of reporting higher work ability with respect to physical (odds ratio (OR) 0.30, 95% CI 0.20 to 0.46) and mental (OR 0.40, 0.27 to 0.62) demands among those with PCC compared to those without. Higher age and history of psychiatric diagnosis were associated with a more substantial reduction in current work ability. 5.8% of those with PCC reported direct effects of PCC on their occupational situation, with 1.6% of those with PCC completely dropping out of the workforce and 43% of those with PCC-related occupational changes reporting financial difficulties as a result.LimitationsSelection, use of self-reported outcome measures, and limited generalizability to individuals with most severe COVID-19 or following vaccination.ConclusionsThese findings highlight the need for providing support and interdisciplinary interventions to individuals affected by PCC to help them maintain or regain their work ability and productivity.Primary Funding SourceFederal Office of Public Health, Department of Health of the Canton of Zurich, University of Zurich Foundation, Switzerland.Study RegistrationISRCTN14990068.

Following acute infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) a significant proportion of individuals develop prolonged symptoms, a serious condition termed post-acute coronavirus disease 2019 (COVID-19) syndrome (PACS) or long COVID. Predictors of PACS are needed. In a prospective multicentric cohort study of 215 individuals, we study COVID-19 patients during primary infection and up to one year later, compared to healthy subjects. We discover an immunoglobulin (Ig) signature, based on total IgM and IgG3 levels, which – combined with age, history of asthma bronchiale, and five symptoms during primary infection – is able to predict the risk of PACS independently of timepoint of blood sampling. We validate the score in an independent cohort of 395 individuals with COVID-19. Our results highlight the benefit of measuring Igs for the early identification of patients at high risk for PACS, which facilitates the study of targeted treatment and pathomechanisms of PACS., Studying a prospective cohort, the authors develop and validate a predictive score for post-acute COVID-19 syndrome, also known as long-COVID. This score relies on an immunoglobulin signature and is independent of timepoint of blood sampling.

Effective public-health measures and vaccination campaigns against SARS-CoV-2 require granular knowledge of population-level immune responses. We developed a Tripartite Automated Blood Immunoassay (TRABI) to assess the IgG response against the ectodomain and the receptor-binding domain of the spike protein as well as the nucleocapsid protein of SARS-CoV-2. We used TRABI for continuous seromonitoring of hospital patients and healthy blood donors (n=72’222) in the canton of Zurich from December 2019 to December 2020 (pre-vaccine period). Seroprevalence peaked in May 2020 and rose again in November 2020 in both cohorts. Validations of results included antibody diffusional sizing and Western Blotting. Using an extended Susceptible-Exposed-Infectious-Removed model, we found that antibodies waned with a half-life of 75 days, whereas the cumulative incidence rose from 2.3% in June 2020 to 12.2% in mid-December 2020 in the population of the canton of Zurich. A follow-up health survey indicated that about 10% of patients infected with wildtype SARS-CoV-2 sustained some symptoms at least twelve months post COVID-19 and up to the timepoint of survey participation. Crucially, we found no evidence for a difference in long-term complications between those whose infection was symptomatic and those with asymptomatic acute infection. The cohort of asymptomatic SARS-CoV-2- infected subjects represents a resource for the study of chronic and possibly unexpected sequelae.

This research project evaluates the impact of systematic (organized) mammography screening compared to no screening. In order to do so, different aspects, such as mortality, harms and tumor stage shift, are assessed.

This systematic review aims to summarize and evaluate the evidence regarding possible differences in performance (or quality) indicators of breast cancer screening through systematic (organized) breast cancer screening programs compared with opportunistic breast cancer screening.

This research project aims to summarize the published evidence regarding the cost-effectiveness of systematic (organized) breast cancer screening compared to no screening or opportunistic (non-systematic) screening and to estimate the potential budget impact of breast cancer screening in the Canton of Zurich, Switzerland.

Background In metastatic hormone-sensitive prostate cancer (mHSPC) treatment, survival benefits have been shown by adding docetaxel or recent androgen receptor axis-targeted therapies (ARATs) abiraterone, apalutamide, or enzalutamide to androgen deprivation therapy (ADT). However, the optimal treatment strategy in terms of costs and effects is unclear, not least due to high ARAT costs. Methods To assess treatment cost-effectiveness, we developed a Markov cohort model with health states of progression-free disease, progressive disease and death for men with newly diagnosed mHSPC, with a 30-year time horizon. Survival data, adverse events and utilities were informed by randomized controlled trial results, our meta-analysis of re-created individual patient survival data, and publicly available sources of unit costs. We applied a Swiss healthcare payer perspective and discounted costs and effects by 3%. Results We found a significant overall survival benefit for ADT+abiraterone versus ADT+docetaxel. The corresponding incremental cost-effectiveness ratio (ICER) was predicted to be EUR 39,814 per quality-adjusted life-year (QALY) gained. ADT+apalutamide and ADT+enzalutamide incurred higher costs and lower QALYs compared to ADT+abiraterone. For all ARATs, drug costs constituted the most substantial cost component. Results were stable except for a large univariable reduction in the pre-progression utility under ADT+abiraterone and very large variations in drug prices. Conclusions Our model projected ADT+abiraterone to be cost-effective compared to ADT+docetaxel at a willingness-to-pay threshold of EUR 70,400/QALY (CHF 100,000 applying purchasing power parities). Given lower estimated QALYs for ADT+apalutamide and ADT+enzalutamide compared to ADT+abiraterone, the former only became cost-effective (the preferred) treatment option(s) at substantial 75–80% (80–90%) price reductions.

This research project aims at eliciting patient preferences regarding the expected benefits and potential harms of the different available treatment options for metastatic hormone-sensitive prostate cancer (mHSPC) in Switzerland.

Participants of randomized controlled trials (RCTs) sometimes receive the intervention (e.g., a drug or drug combination, surgical procedure, behavioral program, screening intervention etc.) initially allocated to a respective comparator arm (i.e., participants in the intervention group receive the control group’s intervention and vice versa). Reasons for the reception of a comparator intervention are manifold; they include patient-related, practical and/or ethical issues. However, such changes may affect the interpretation of the comparisons and the translation of study results into clinical practice (e.g., through clinical guidelines). The aim of the current methodological review is to i) explore and assess the frequency of trial participants in the control arm receiving the intervention planned for intervention arm and vice versa in recent RCTs and the modalities of this practice (e.g., reasons, decision criteria, pre-specification and awareness to allocation of participants and personnel); and ii) to identify similarities and differences in trials across intervention types and clinical fields.

BACKGROUND Digital proximity tracing apps have been deployed in multiple countries to assist with SARS-CoV-2 pandemic mitigation efforts. However, it is unclear how their performance and effectiveness were affected by changing pandemic contexts and new viral variants of concern. OBJECTIVE The aim of this study is to bridge these knowledge gaps through a country-wide digital proximity tracing app effectiveness assessment as guided by the WHO/ECDC framework. Specifically, we performed a descriptive analysis of the digital proximity tracing app in Switzerland for three different time periods where different SARS-CoV-2 variants of concern (i.e., Alpha, Delta, and Omicron, respectively) were most prevalent. METHODS In our study, we refer to the indicator framework for the evaluation of public health effectiveness of digital proximity tracing apps of the World Health Organization / European Center for Disease Control (WHO/ECDC). We applied this framework to compare performance and effectiveness indicators of the SwissCovid app in Switzerland across three time periods that were characterized by the dominance of the Alpha, Delta, and Omicron variants of concern. RESULTS Average daily registered SARS-CoV-2 case rates during our assessment period from January 25, 2021 to March 19, 2022 were 20 (Alpha), 54 (Delta), and 350 (Omicron) per 100’000 inhabitants. The percentages of overall entered authentication codes from positive tests in the SwissCovid app were 10%, 4%, and 5% during the Alpha, Delta, and Omicron variant phases, respectively. Following receipt of an exposure notification from the SwissCovid app, 58% (Alpha), 44% (Delta), and 73% (Omicron) of app users sought testing or performed self-tests. Test positivity among these exposure-notified individuals was 19% in the Alpha (compared with 6% in the general population), 29% (11%) in the Delta, and 41% (43%) in the Omicron variant phases. In addition, 34% (Alpha), 19% (Delta), and 30% (Omicron) of exposure-notified app users reported receiving mandatory quarantine orders by manual contact tracing or through a recommendation by a health care professional. CONCLUSIONS In constantly evolving pandemic contexts, the effectiveness of digital proximity tracing apps in contributing to mitigating pandemic spread should be reviewed regularly and adapted based on changing requirements. The WHO/ECDC framework allowed us to assess relevant domains of digital proximity tracing in a holistic and systematic approach. Future implementation of digital proximity tracing apps should place more emphasis on the social, psychological and organizational aspects to reduce bottlenecks and facilitate their use in pandemic situations.

ImportanceWhile much of the attention on the COVID-19 pandemic was directed at the daily counts of cases and those with serious disease overwhelming health services, increasingly, reports have appeared of people who experience debilitating symptoms after the initial infection. This is popularly known as long COVID.ObjectiveTo estimate by country and territory of the number of patients affected by long COVID in 2020 and 2021, the severity of their symptoms and expected pattern of recoveryDesignWe jointly analyzed ten ongoing cohort studies in ten countries for the occurrence of three major symptom clusters of long COVID among representative COVID cases. The defining symptoms of the three clusters (fatigue, cognitive problems, and shortness of breath) are explicitly mentioned in the WHO clinical case definition. For incidence of long COVID, we adopted the minimum duration after infection of three months from the WHO case definition. We pooled data from the contributing studies, two large medical record databases in the United States, and findings from 44 published studies using a Bayesian meta-regression tool. We separately estimated occurrence and pattern of recovery in patients with milder acute infections and those hospitalized. We estimated the incidence and prevalence of long COVID globally and by country in 2020 and 2021 as well as the severity-weighted prevalence using disability weights from the Global Burden of Disease study.ResultsAnalyses are based on detailed information for 1906 community infections and 10526 hospitalized patients from the ten collaborating cohorts, three of which included children. We added published data on 37262 community infections and 9540 hospitalized patients as well as ICD-coded medical record data concerning 1.3 million infections. Globally, in 2020 and 2021, 144.7 million (95% uncertainty interval [UI] 54.8–312.9) people suffered from any of the three symptom clusters of long COVID. This corresponds to 3.69% (1.38–7.96) of all infections. The fatigue, respiratory, and cognitive clusters occurred in 51.0% (16.9–92.4), 60.4% (18.9–89.1), and 35.4% (9.4–75.1) of long COVID cases, respectively. Those with milder acute COVID-19 cases had a quicker estimated recovery (median duration 3.99 months [IQR 3.84–4.20]) than those admitted for the acute infection (median duration 8.84 months [IQR 8.10–9.78]). At twelve months, 15.1% (10.3–21.1) continued to experience long COVID symptoms.Conclusions and relevanceThe occurrence of debilitating ongoing symptoms of COVID-19 is common. Knowing how many people are affected, and for how long, is important to plan for rehabilitative services and support to return to social activities, places of learning, and the workplace when symptoms start to wane.Key PointsQuestionWhat are the extent and nature of the most common long COVID symptoms by country in 2020 and 2021?FindingsGlobally, 144.7 million people experienced one or more of three symptom clusters (fatigue; cognitive problems; and ongoing respiratory problems) of long COVID three months after infection, in 2020 and 2021. Most cases arose from milder infections. At 12 months after infection, 15.1% of these cases had not yet recovered.MeaningThe substantial number of people with long COVID are in need of rehabilitative care and support to transition back into the workplace or education when symptoms start to wane.

BACKGROUND Digital proximity tracing apps have been deployed in multiple countries to assist with SARS-CoV-2 pandemic mitigation efforts. However, it is unclear how their performance and effectiveness were affected by changing pandemic contexts and new viral variants of concern. OBJECTIVE The aim of this study is to bridge these knowledge gaps through a country-wide digital proximity tracing app effectiveness assessment as guided by the WHO/ECDC framework. Specifically, we performed a descriptive analysis of the digital proximity tracing app in Switzerland for three different time periods where different SARS-CoV-2 variants of concern (i.e., Alpha, Delta, and Omicron, respectively) were most prevalent. METHODS In our study, we refer to the indicator framework for the evaluation of public health effectiveness of digital proximity tracing apps of the World Health Organization / European Center for Disease Control (WHO/ECDC). We applied this framework to compare performance and effectiveness indicators of the SwissCovid app in Switzerland across three time periods that were characterized by the dominance of the Alpha, Delta, and Omicron variants of concern. RESULTS Average daily registered SARS-CoV-2 case rates during our assessment period from January 25, 2021 to March 19, 2022 were 20 (Alpha), 54 (Delta), and 350 (Omicron) per 100'000 inhabitants. The percentages of overall entered authentication codes from positive tests in the SwissCovid app were 10%, 4%, and 5% during the Alpha, Delta, and Omicron variant phases, respectively. Following receipt of an exposure notification from the SwissCovid app, 58% (Alpha), 44% (Delta), and 73% (Omicron) of app users sought testing or performed self-tests. Test positivity among these exposure-notified individuals was 19% in the Alpha (compared with 6% in the general population), 29% (11%) in the Delta, and 41% (43%) in the Omicron variant phases. In addition, 34% (Alpha), 19% (Delta), and 30% (Omicron) of exposure-notified app users reported receiving mandatory quarantine orders by manual contact tracing or through a recommendation by a health care professional. CONCLUSIONS In constantly evolving pandemic contexts, the effectiveness of digital proximity tracing apps in contributing to mitigating pandemic spread should be reviewed regularly and adapted based on changing requirements. The WHO/ECDC framework allowed us to assess relevant domains of digital proximity tracing in a holistic and systematic approach. While the Swisscovid app mostly worked as expected, our analysis revealed room for optimizations and further performance improvements. Future implementation of digital proximity tracing apps should place more emphasis on the social, psychological and organizational aspects to reduce bottlenecks and facilitate their use in pandemic situations. CLINICALTRIAL

ImportanceLong-term control of SARS-CoV-2 requires effective vaccination strategies. This has been challenged by public mistrust and spread of misinformation regarding vaccine safety. Hence, better understanding and communication on the longer-term and comparative experiences of general population individuals following SARS-CoV-2 vaccination are required.ObjectiveTo evaluate and compare self-reported adverse effects following SARS-CoV-2 vaccination, participants’ perceptions regarding vaccinations and their compliance with recommended public health measures.Design, Setting and ParticipantsPopulation-based longitudinal cohort of 575 adults, randomly selected from all individuals presenting to the reference vaccination center of the Canton of Zurich, Switzerland, for receipt of BNT162b2, mRNA1273, or JNJ-78436735.ExposuresBNT162b2, mRNA1273, or JNJ-78436735 vaccines.Main Outcomes and MeasuresPrimary outcomes included period prevalence, onset, duration, and severity of self-reported adverse effects over 12 weeks following vaccination with a specific focus on the proportion of participants reporting allergic reactions, menstrual irregularities, or cardiac adverse effects, or requiring hospitalization. Secondary outcomes included risk factors associated with reporting adverse effects, perception of vaccine importance, trust in public health authorities and pharmaceutical companies, and compliance with recommended public health measures.Results454 (79.0%) participants reported at least one adverse effect during 12 weeks after vaccination. Prevalence was highest among mRNA-1273 recipients (88.7% vs. 77.3% after BNT162b2, 69.1% after JNJ-78436735). Most adverse effects were systemic (72%), occurred within 24 hours (67.9%), and resolved in less than three days (76.3%). 85.2% were reported as mild or moderate. Allergic reactions were reported by 0.4% of participants, hospitalizations by 0.7%, cardiac adverse effects by 1.4%. Menstrual irregularities were reported by 9% of female participants younger than 50 years. Female sex, younger age, higher education, and receipt of mRNA-1273 were associated with reporting adverse effects. Compared to JNJ-78436735 recipients, a higher proportion of mRNA vaccine recipients agreed that vaccination is important (87.5% vs. 28.5%), and trusted public health authorities (80.2% vs. 30.3%) and pharmaceutical companies (71.7% vs. 23.6%).Conclusions and RelevanceOur population-based cohort provided real-world data on self-reported adverse effects following SARS-CoV-2 vaccination and highlights the importance of transparent communication regarding adverse effects and building trust in public health authorities to ensure successful future vaccination campaigns.Main PointsOur representative population-based cohort study demonstrated the safety of three SARS-CoV-2 vaccines and provides real-world estimates on adverse effect incidence.Transparent communication of expected adverse effects to vaccine-seeking individuals is pivotal to build trust in current or future vaccination campaigns.

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.

BackgroundPost COVID-19 condition (PCC) is an important complication of SARS-CoV-2 infection, affecting millions worldwide. Further evidence is needed on the risk of PCC after vaccination and infection with newer variants. This study aimed to evaluate the prevalence and severity of PCC across different variants and vaccination histories.MethodsWe used pooled data from 1350 SARS-CoV-2-infected individuals from two representative population-based cohorts in Switzerland, diagnosed between Aug 5, 2020, and Feb 25, 2022. We descriptively analysed the prevalence and severity of PCC, defined as the presence and frequency of PCC-related symptoms six months after infection, among vaccinated and non-vaccinated individuals infected with Wildtype, Delta, and Omicron SARS-CoV-2. We used multivariable logistic regression models to assess the association and estimate the risk reduction of PCC after infection with newer variants and prior vaccination. We further assessed associations with the severity of PCC using multinomial logistic regression. To identify groups of individuals with similar symptom patterns and evaluate differences in the presentation of PCC across variants, we performed exploratory hierarchical cluster analyses.FindingsWe found strong evidence that vaccinated individuals infected with Omicron had a reduced risk of developing PCC compared to non-vaccinated Wildtype-infected individuals (odds ratio 0.42, 95% confidence interval 0.24–0.68). The risk among non-vaccinated individuals was similar after infection with Delta or Omicron compared to Wildtype SARS-CoV-2. We found no differences in PCC prevalence with respect to the number of received vaccine doses or timing of last vaccination. The prevalence of PCC-related symptoms among vaccinated, Omicron-infected individuals was lower across severity levels. In cluster analyses, we identified four clusters of diverse systemic, neurocognitive, cardiorespiratory, and musculoskeletal symptoms, with similar patterns across variants.InterpretationThe risk of PCC appears to be lowered with infection by the Omicron variant and after prior vaccination. This evidence is crucial to guide future public health measures and vaccination strategies.FundingSwiss School of Public Health (SSPH+), University of Zurich Foundation, Cantonal Department of Health Zurich, Swiss Federal Office of Public HealthStudy registrationsISRCTN14990068, ISRCTN18181860Research in contextEvidence before this studyWe searched MEDLINE, EMBASE, and medRxiv for primary studies assessing the prevalence and symptoms associated with post COVID-19 condition (PCC) after infection with different SARS-CoV-2 variants and among infected individuals with and without prior vaccination. We used a specific search strategy limited to the timeframe between Jan 01, 2020, and Aug 29, 2022, without language restriction (reported in Supplementary Table S1). We further searched identified systematic reviews for additional references. We screened 221 unique records and identified four studies investigating the association of Delta or Omicron variant infections and 11 studies investigating the association of prior vaccination with PCC.Current evidence is uncertain whether infection with emerging variants may be associated with a reduction of the risk of developing PCC. Two studies found a decreased risk of PCC with Omicron compared to Delta infection, or to individuals infected during any prior wave. One study found a lower risk of PCC with Alpha compared to Wildtype SARS-CoV-2, but an increased risk among those infected with the Delta or Omicron variant. One study primarily examined symptom clusters across different waves. All identified studies defined PCC as symptoms occurring at ≥4 weeks or ≥12 weeks after infection, and were conducted among hospitalised patients, healthcare workers, or users of the United Kingdom ZOE symptom app.Evidence regarding the preventive effects of vaccination on PCC was of higher certainty, with eight out of 11 studies reporting a substantially reduced PCC incidence with mRNA- and adenovirus vector-based vaccines. The magnitude of the effect in these studies varied, with estimated adjusted odds ratios ranging from 0.22 to 0.85. Nonetheless, three studies found no difference between vaccinated and non-vaccinated infected individuals, including two of three studies evaluating PCC at six months after infection. The third study with a six-month horizon found a higher odds ratio than any other study reporting a reduction at ≥4 weeks or ≥12 weeks. Study populations and designs varied strongly, and only one study evaluated the independent effects of SARS-CoV-2 variants and vaccination.Added value of this studyThis study investigates the association of PCC with infection with Delta and Omicron variants and prior vaccination compared to Wildtype SARS-CoV-2 infection among unvaccinated individuals. We found that infection with the Omicron variant and prior vaccination were associated with a lower risk of developing PCC six months after infection. Compared to previous work, this study is the first to evaluate PCC with a longer-term follow-up, while simultaneously evaluating the risk reduction by Delta and Omicron variants and prior vaccination on PCC. By relying on prospectively collected data from two representative population-based cohorts, we were able to provide an in-depth analysis of the longer-term risk reduction through prior vaccination and novel variants, the severity of PCC-related symptoms, and symptom clusters across pandemic waves between 2020 and early 2022.Implications of all the available evidenceIn conjunction with existing evidence, our study suggests that infection with the Omicron variant and prior vaccination are likely to substantially reduce the risk of developing PCC compared to infection with Wildtype SARS-CoV-2 without prior vaccination. We demonstrate that this risk reduction persists up to six months after infection, and that PCC-related symptoms are reduced to a similar extent across different levels of severity. However, the risk of having mild to even potentially severe PCC six months after infection is not eliminated. Hence, vaccinations will likely continue to be an important mainstay in the management of the further course of the pandemic. The prevention of further infection and PCC may still provide important benefits for public health, even if SARS-CoV-2 further evolves to cause milder infections and becomes endemic. Therefore, information from this study will be crucial to guide vaccination strategies and decisions on timing and enforcement of public health measures worldwide.

BackgroundEvidence 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.ObjectivesTo evaluate longer-term symptoms and health outcomes within a cohort of SARS-CoV-2 infected individuals.DesignPopulation-based, longitudinal cohort.SettingGeneral population, Canton of Zurich, Switzerland.Patients1543 adults with confirmed SARS-CoV-2 infection and 628 adults without infection.MeasurementsChanges 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.Results25% 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.LimitationsWe relied on self-reported assessments and did not assess the effects of vaccination or infection with emerging variants of concern.ConclusionThese 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.

Objectives: To synthesize existing evidence on prevalence as well as clinical and socio-economic aspects of Long COVID. Methods: An umbrella review of reviews and a targeted evidence synthesis of their primary studies, including searches in four electronic databases, reference lists of included reviews, as well as related article lists of relevant publications. Results: Synthesis included 23 reviews and 102 primary studies. Prevalence estimates ranged from 7.5% to 41% in non-hospitalized adults, 2.3%–53% in mixed adult samples, 37.6% in hospitalized adults, and 2%–3.5% in primarily non-hospitalized children. Preliminary evidence suggests that female sex, age, comorbidities, the severity of acute disease, and obesity are associated with Long COVID. Almost 50% of primary studies reported some degree of Long COVID-related social and family-life impairment, long absence periods off work, adjusted workloads, and loss of employment. Conclusion: Long COVID will likely have a substantial public health impact. Current evidence is still heterogeneous and incomplete. To fully understand Long COVID, well-designed prospective studies with representative samples will be essential., Public Health Reviews, 43

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. CLINICALTRIAL International Standard Randomised Controlled Trial Number Registry 14990068; https://doi.org/10.1186/ISRCTN14990068

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