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Seroprevalence studies have been used throughout the COVID-19 pandemic to monitor infection and immunity. These studies are often reported in peer-reviewed journals, but the academic writing and publishing process can delay reporting and thereby public health action. Seroprevalence estimates have been reported faster in preprints and media, but with concerns about data quality. We aimed to (i) describe the timeliness of SARS-CoV-2 serosurveillance reporting by publication venue and study characteristics and (ii) identify relationships between timeliness, data validity, and representativeness to guide recommendations for serosurveillance efforts.We included seroprevalence studies published between January 1, 2020 and December 31, 2021 from the ongoing SeroTracker living systematic review. For each study, we calculated timeliness as the time elapsed between the end of sampling and the first public report. We evaluated data validity based on serological test performance and correction for sampling error, and representativeness based on use of a representative sample frame and adequate sample coverages. We examined how timeliness varied with study characteristics, representativeness, and data validity using univariate and multivariate Cox regression.We analyzed 1,844 studies. Median time to publication was 154 days (IQR 64-255), varying by publication venue (journal articles: 212 days, preprints: 101 days, institutional reports: 18 days, and media: 12 days). Multivariate analysis confirmed the relationship between timeliness and publication venue and showed that general population studies were published faster than special population or health care worker studies; there was no relationship between timeliness and study geographic scope, geographic region, representativeness, or serological test performance.Seroprevalence studies in peer-reviewed articles and preprints are published slowly, highlighting the limitations of using the academic literature to report seroprevalence during a health crisis. More timely reporting of seroprevalence estimates can improve their usefulness for surveillance, enabling more effective responses during health emergencies.

SummaryBackgroundWe aimed to systematically review the magnitude and duration of the protective effectiveness of prior infection (PE) and hybrid immunity (HE) against Omicron infection and severe disease.MethodsWe searched pre-print and peer-reviewed electronic databases for controlled studies from January 1, 2020, to June 1, 2022. Risk of bias (RoB) was assessed using the Risk of Bias In Non-Randomized Studies of Interventions (ROBINS-I)-Tool. We used random-effects meta-regression to estimate the magnitude of protection at 1-month intervals and the average change in protection since the last vaccine dose or infection from 3 months to 6 or 12 months. We compared our estimates of PE and HE to previously published estimates of the magnitude and durability of vaccine effectiveness (VE) against Omicron.FindingsEleven studies of prior infection and 15 studies of hybrid immunity were included. For prior infection, there were 97 estimates (27 at moderate RoB and 70 at serious RoB), with the longest follow up at 15 months. PE against hospitalization or severe disease was 82·5% [71·8-89·7%] at 3 months, and 74·6% [63·1-83·5%] at 12 months. PE against reinfection was 65·2% [52·9-75·9%] at 3 months, and 24·7% [16·4-35·5%] at 12 months. For HE, there were 153 estimates (78 at moderate RoB and 75 at serious RoB), with the longest follow up at 11 months for primary series vaccination and 4 months for first booster vaccination. Against hospitalization or severe disease, HE involving either primary series vaccination or first booster vaccination was consistently >95% for the available follow up. Against reinfection, HE involving primary series vaccination was 69·0% [58·9-77·5%] at 3 months after the most recent infection or vaccination, and 41·8% [31·5-52·8%] at 12 months, while HE involving first booster vaccination was 68·6% [58·8-76·9%] at 3 months, and 46·5% [36·0-57·3%] at 6 months. Against hospitalization or severe disease at 6 months, hybrid immunity with first booster vaccination (effectiveness 95·3% [81·9-98·9%]) or with primary series alone (96·5% [90·2-98·8%]) provided significantly greater protection than prior infection alone (80·1% [70·3-87·2%]), first booster vaccination alone (76·7% [72·5-80·4%]), or primary series alone (64·6% [54·5-73·6%]). Results for protection against reinfection were similar.InterpretationPrior infection and hybrid immunity both provided greater and more sustained protection against Omicron than vaccination alone. All protection estimates waned quickly against infection but remained high for hospitalisation or severe disease. Individuals with hybrid immunity had the highest magnitude and durability of protection against all outcomes, reinforcing the global imperative for vaccination.FundingWHO COVID-19 Solidarity Response Fund and the Coalition for Epidemic Preparedness Innovations.Research in contextEvidence before this studyThe global emergence and rapid spread of Omicron (B.1.1.529) variant of concern, characterized by their ability to escape immunity, has required scientists and policymakers to reassess the population protection against Omicron infection and severe disease. So far, few systematic reviews have incorporated data on Omicron, and none have examined the protection against Omicron conferred by hybrid immunity (i.e. the immunity gained from the combination of vaccination and prior infection) which is now widespread globally. While one preprint has recently reported protection from prior infection over time, no systematic review has systematically compared the magnitude and duration of vaccination, prior infection, and hybrid immunity. A large single-country study has reported that protection from either infection or hybrid immunity against Omicron infection wanes to low levels at 15 months, but is relatively stable against severe disease.Added value of this studyPrior infection and hybrid immunity both provided greater and more sustained protection against Omicron than vaccination alone. Individuals with hybrid immunity had the highest magnitude and durability of protection against all outcomes; protection against severe disease remained above 95% until the end of available follow-up at 11 months after hybrid immunity with primary series and 4 months after hybrid immunity with booster vaccination, and was sustained at these high levels of protection in projections to 12 months and 6 months, respectively.Implications of all the available evidenceThese results may serve to tailor guidance on the optimal number and timing of vaccinations. At the public health level, these findings can be combined with data on local infection prevalence, vaccination rates, and their timing. In settings with high seroprevalence, limited resources, and competing health priorities, it may be reasonable to focus on achieving high coverage rates with primary series among individuals who are at higher risk of poor outcome, as this will provide a high level of protection against severe disease for at least one year among those with prior infection. Furthermore, given the waning protection for both infection-and vaccine induced immunity against infection or reinfection, mass vaccination could be timed for roll-out prior to periods of expected increased incidence, such as the winter season. At the individual level, these results can be combined with knowledge of a person’s infection and vaccination history. A six-month delay in booster may be justified after the last infection or vaccination for individuals with a known prior infection and full primary series vaccination. Further follow-up of the protective effectiveness of hybrid immunity against hospitalization or severe disease for all vaccines is needed to clarify how much waning of protection might occur with longer duration since the last infection or vaccination. Producing estimates of protection for new variant-containing vaccines will be crucial for COVID-19 vaccine policy and decision-making bodies. Policy makers considering the use and timing of vaccinations should include the local extent of past infection, the protection conferred by prior infection or hybrid immunity, and the duration of this protection as key considerations to inform their decision-making.

International audience; The COVID-19 pandemic caught the world largely unprepared, including scientific and policy communities. On April 10-13, 2022, researchers across academia, industry, government, and nonprofit organizations met at the Keystone symposium "Lessons from the Pandemic: Responding to Emerging Zoonotic Viral Diseases" to discuss the successes and challenges of the COVID-19 pandemic and what lessons can be applied moving forward. Speakers focused on experiences not only from the COVID-19 pandemic but also from outbreaks of other pathogens, including the Ebola virus, Lassa virus, and Nipah virus. A general consensus was that investments made during the COVID-19 pandemic in infrastructure, collaborations, laboratory and manufacturing capacity, diagnostics, clinical trial networks, and regulatory enhancements-notably, in low-to-middle income countries-must be maintained and strengthened to enable quick, concerted responses to future threats, especially to zoonotic pathogens.

The laborious and time-consuming nature of systematic review production hinders the dissemination of up-to-date evidence synthesis. Well-performing natural language processing (NLP) tools for systematic reviews have been developed, showing promise to improve efficiency. However, the feasibility and value of these technologies have not been comprehensively demonstrated in a real-world review. We developed an NLP-assisted abstract screening tool that provides text inclusion recommendations, keyword highlights, and visual context cues. We evaluated this tool in a living systematic review on SARS-CoV-2 seroprevalence, conducting a quality improvement assessment of screening with and without the tool. We evaluated changes to abstract screening speed, screening accuracy, characteristics of included texts, and user satisfaction. The tool improved efficiency, reducing screening time per abstract by 45.9% and decreasing inter-reviewer conflict rates. The tool conserved precision of article inclusion (positive predictive value; 0.92 with tool vs 0.88 without) and recall (sensitivity; 0.90 vs 0.81). The summary statistics of included studies were similar with and without the tool. Users were satisfied with the tool (mean satisfaction score of 4.2/5). We evaluated an abstract screening process where one human reviewer was replaced with the tool’s votes, finding that this maintained recall (0.92 one-person, one-tool vs 0.90 two tool-assisted humans) and precision (0.91 vs 0.92) while reducing screening time by 70%. Implementing an NLP tool in this living systematic review improved efficiency, maintained accuracy, and was well-received by researchers, demonstrating the real-world effectiveness of NLP in expediting evidence synthesis.

IntroductionEstimating COVID-19 cumulative incidence in Africa remains problematic due to challenges in contact tracing, routine surveillance systems and laboratory testing capacities and strategies. We undertook a meta-analysis of population-based seroprevalence studies to estimate SARS-CoV-2 seroprevalence in Africa to inform evidence-based decision making on public health and social measures (PHSM) and vaccine strategy.MethodsWe searched for seroprevalence studies conducted in Africa published 1 January 2020–30 December 2021 in Medline, Embase, Web of Science and Europe PMC (preprints), grey literature, media releases and early results from WHO Unity studies. All studies were screened, extracted, assessed for risk of bias and evaluated for alignment with the WHO Unity seroprevalence protocol. We conducted descriptive analyses of seroprevalence and meta-analysed seroprevalence differences by demographic groups, place and time. We estimated the extent of undetected infections by comparing seroprevalence and cumulative incidence of confirmed cases reported to WHO.PROSPERO: CRD42020183634.ResultsWe identified 56 full texts or early results, reporting 153 distinct seroprevalence studies in Africa. Of these, 97 (63%) were low/moderate risk of bias studies. SARS-CoV-2 seroprevalence rose from 3.0% (95% CI 1.0% to 9.2%) in April–June 2020 to 65.1% (95% CI 56.3% to 73.0%) in July–September 2021. The ratios of seroprevalence from infection to cumulative incidence of confirmed cases was large (overall: 100:1, ranging from 18:1 to 954:1) and steady over time. Seroprevalence was highly heterogeneous both within countries—urban versus rural (lower seroprevalence for rural geographic areas), children versus adults (children aged 0–9 years had the lowest seroprevalence)—and between countries and African subregions.ConclusionWe report high seroprevalence in Africa suggesting greater population exposure to SARS-CoV-2 and potential protection against COVID-19 severe disease than indicated by surveillance data. As seroprevalence was heterogeneous, targeted PHSM and vaccination strategies need to be tailored to local epidemiological situations.

Wearable sensors can continuously and passively detect potential respiratory infections, before or absent symptoms. However, the population-level impact of deploying these devices during pandemics is unclear. We built a compartmental model of Canada’s second COVID-19 wave and simulated wearable sensor deployment scenarios, systematically varying detection algorithm accuracy, uptake, and adherence. With current detection algorithms and 4% uptake, we found that deploying wearable sensors could have averted 9% of second wave SARS-CoV-2 infections, though 29% of this reduction is attributed to incorrectly quarantining uninfected device users. Improving detection specificity and offering confirmatory rapid tests each minimized incorrect quarantines and associated costs. With a sufficiently low false positive rate, increasing uptake and adherence became effective strategies for scaling averted infections. We concluded that wearable sensor deployment can meaningfully contribute to pandemic mitigation; in the case of COVID-19, technology improvements or supporting measures are required to reduce social and economic costs to acceptable levels.

BackgroundRisk of bias (RoB) assessments are a core element of evidence synthesis but can be time consuming and subjective. We aimed to develop a decision rule-based algorithm for RoB assessment of seroprevalence studies.MethodsWe developed the SeroTracker-RoB algorithm. The algorithm derives seven objective and two subjective critical appraisal items from the Joanna Briggs Institute Critical Appraisal Checklist for Prevalence studies and implements decision rules that determine study risk of bias based on the items. Decision rules were validated using the SeroTracker seroprevalence study database, which included non-algorithmic RoB judgements from two reviewers. We quantified efficiency as the mean difference in time for the algorithmic and non-algorithmic assessments of 80 randomly selected articles, coverage as the proportion of studies where the decision rules yielded an assessment, and reliability using intraclass correlations comparing algorithmic and non-algorithmic assessments for 2,070 articles.ResultsA set of decision rules with 61 branches was developed using responses to the nine critical appraisal items. The algorithmic approach was faster than non-algorithmic assessment (mean reduction 2.32 minutes [SD 1.09] per article), classified 100% (n=2,070) of studies, and had good reliability compared to non-algorithmic assessment (ICC 0.77, 95% CI 0.74-0.80). We built the SeroTracker-RoB Excel Tool which embeds this algorithm for use by other researchers.ConclusionsThe SeroTracker-RoB decision-rule based algorithm was faster than non-algorithmic assessment with complete coverage and good reliability. This algorithm enabled rapid, transparent, and reproducible RoB evaluations of seroprevalence studies and may support evidence synthesis efforts during future disease outbreaks. This decision rule-based approach could be applied to other types of prevalence studies.

Population-level immune surveillance, which includes monitoring exposure and assessing vaccine-induced immunity, is a crucial component of public health decision-making during a pandemic. Serosurveys estimating the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in the population played a key role in characterizing SARS-CoV-2 epidemiology during the early phases of the pandemic. Existing serosurveys provide infrastructure to continue immune surveillance but must be adapted to remain relevant in the SARS-CoV-2 vaccine era. Here, we delineate how SARS-CoV-2 serosurveys should be designed to distinguish infection- and vaccine-induced humoral immune responses to efficiently monitor the evolution of the pandemic. We discuss how serosurvey results can inform vaccine distribution to improve allocation efficiency in countries with scarce vaccine supplies and help assess the need for booster doses in countries with substantial vaccine coverage.

Les TDRA detectent les antigenes du SRAS-CoV-2 dans des echantillons preleves des voies respiratoires superieures et fournissent le resultat dans un intervalle de 15–30 minutes. L’eventail de sensibilite de ces tests de detection est de 30 %–80 % et leur gamme de specificite est de

[See related article at [www.cmaj.ca/lookup/doi/10.1503/cmaj.210100][2]][2] RATs detect SARS-CoV-2 antigens in samples from the upper respiratory tract and provide results in 15–30 minutes. Test sensitivities range from 30% to 80%, and specificities range from 98% to 100%, relative to reverse

The accuracy of many apex locators is affected by electrolytes including sodium hypochlorite. According to the manufacturer a new device, the ENDEX, overcomes this problem. The purpose of this study was to assess the accuracy of the ENDEX in comparison with a traditional device, the RCM Mark II. The lengths of 61 canals with various contents (vital pulp, necrotic pulp, pus/exudate, sodium hypochlorite, and water) were determined in vivo. Files were cemented within the canals at lengths determined by the ENDEX. The teeth were then radiographed and extracted, and the distance between the file tip and apical foramen was recorded. Derived readings for the RCM Mark II were compared with the actual ENDEX reading and corresponding radiograph. The results indicated that most of the file tips that were at the radiographic apex actually extended through the apical foramen, and canal content had a varying effect on each device. The overall accuracy of the ENDEX (71.7%) was higher than that of the RCM Mark II (43.5%) within 0.5 mm of the apical foramen. The ENDEX, unlike the RCM Mark II, proved accurate in the presence of sodium hypochlorite.