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Coronavirus disease (COVID-19)
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A comparison of two registry-based systems for the surveillance of persons hospitalised with COVID-19 in Norway, February 2020 to May 2022
BackgroundThe surveillance of persons hospitalised with COVID-19 has been essential to ensure timely and appropriate public health response. Ideally, surveillance systems should distinguish persons hospitalised with COVID-19 from those hospitalised due to COVID-19.
AimWe compared data in two national electronic health registries in Norway to critically appraise and inform the further development of the surveillance of persons hospitalised with COVID-19.
MethodWe included hospitalised COVID-19 patients registered in the Norwegian Patient Registry (NPR) or the Norwegian Pandemic Registry (NoPaR) with admission dates between 17 February 2020 and 1 May 2022. We linked patients, identified overlapping hospitalisation periods and described the overlap between the registries. We described the prevalence of International Classification of Diseases (ICD-10) diagnosis codes and their combinations by main cause of admission (clinically assessed as COVID-19 or other), age and time.
ResultsIn the study period, 19,486 admissions with laboratory-confirmed COVID-19 were registered in NoPaR and 21,035 with the corresponding ICD-10 code U07.1 in NPR. Up to late 2021, there was a 90–100% overlap between the registries, which thereafter decreased to < 75%. The prevalence of ICD-10 codes varied by reported main cause, age and time.
ConclusionChanges in patient cohorts, virus characteristics and the management of COVID-19 patients from late 2021 impacted the registration of patients and coding practices in the registries. Using ICD-10 codes for the surveillance of persons hospitalised due to COVID-19 requires age- and time-specific definitions and ongoing validation to consider temporal changes in patient cohorts and virus characteristics.
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Epidemiology, surveillance and diagnosis of Usutu virus infection in the EU/EEA, 2012 to 2021
BackgroundUsutu virus (USUV) is a flavivirus with an enzootic cycle between birds and mosquitoes; humans are incidental dead-end hosts. In Europe, the virus was first detected in Italy in 1996; since then, it has spread to many European countries.
AimWe aimed to report on the epidemiology, surveillance, diagnosis and prevention of USUV infection in humans, mosquitoes and other animals in the European Union/European Economic Area (EU/EEA) from 2012 to 2021.
MethodsWe collected information through a literature review, an online survey and an expert meeting.
ResultsEight countries reported USUV infection in humans (105 cases, including 12* with neurological symptoms), 15 countries in birds and seven in mosquitoes. Infected animals were also found among pets, wild and zoo animals. Usutu virus was detected primarily in Culex pipiens but also in six other mosquito species. Detection of USUV infection in humans is notifiable only in Italy, where it is under surveillance since 2017 and now integrated with surveillance in animals in a One Health approach. Several countries include USUV infection in the differential diagnosis of viral encephalitis and arbovirus infections. Animal USUV infection is not notifiable in any EU/EEA country.
ConclusionHuman USUV infections, mainly asymptomatic and, less frequently, with a febrile illness or a neuroinvasive disease, have been reported in several EU/EEA countries, where the virus is endemic. Climate and environmental changes are expected to affect the epidemiology of USUV. A One Health approach could improve the monitoring of its evolution in Europe.
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Relative effectiveness of bivalent Original/Omicron BA.4-5 mRNA vaccine in preventing severe COVID-19 in persons 60 years and above during SARS-CoV-2 Omicron XBB.1.5 and other XBB sublineages circulation, Italy, April to June 2023
Massimo Fabiani , Alberto Mateo-Urdiales , Chiara Sacco , Maria Cristina Rota , Emmanouil Alexandros Fotakis , Daniele Petrone , Martina Del Manso , Andrea Siddu , Paola Stefanelli , Antonino Bella , Flavia Riccardo , Giovanni Rezza , Anna Teresa Palamara , Silvio Brusaferro , Patrizio Pezzotti and on behalf of the Italian Integrated Surveillance of COVID-19 study group and of the Italian COVID-19 Vaccines Registry groupDuring predominant circulation of SARS-CoV-2 Omicron XBB.1.5 and other XBB sublineages (April–June 2023), we found that a second or third booster of Comirnaty bivalent Original/Omicron BA.4-5 mRNA vaccine, versus a first booster received at least 120 days earlier, was effective in preventing severe COVID-19 for more than 6 months post-administration in persons 60 years and above. In view of autumn 2023 vaccination campaigns, use of bivalent Original/Omicron BA.4-5 mRNA vaccines might be warranted until monovalent COVID-19 vaccines targeting Omicron XBB.1 sublineages become available.
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Revisiting the personal protective equipment components of transmission-based precautions for the prevention of COVID-19 and other respiratory virus infections in healthcare
The COVID-19 pandemic highlighted some potential limitations of transmission-based precautions. The distinction between transmission through large droplets vs aerosols, which have been fundamental concepts guiding infection control measures, has been questioned, leading to considerable variation in expert recommendations on transmission-based precautions for COVID-19. Furthermore, the application of elements of contact precautions, such as the use of gloves and gowns, is based on low-quality and inconclusive evidence and may have unintended consequences, such as increased incidence of healthcare-associated infections and spread of multidrug-resistant organisms. These observations indicate a need for high-quality studies to address the knowledge gaps and a need to revisit the theoretical background regarding various modes of transmission and the definitions of terms related to transmission. Further, we should examine the implications these definitions have on the following components of transmission-based precautions: (i) respiratory protection, (ii) use of gloves and gowns for the prevention of respiratory virus infections, (iii) aerosol-generating procedures and (iv) universal masking in healthcare settings as a control measure especially during seasonal epidemics. Such a review would ensure that transmission-based precautions are consistent and rationally based on available evidence, which would facilitate decision-making, guidance development and training, as well as their application in practice.
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Seroprevalence for Borrelia burgdorferi sensu lato and tick-borne encephalitis virus antibodies and associated risk factors among forestry workers in northern France, 2019 to 2020
BackgroundLyme borreliosis (LB) is the most common tick-borne disease (TBD) in France. Forestry workers are at high risk of TBD because of frequent exposure to tick bites.
AimWe aimed to estimate the seroprevalence of Borrelia burgdorferi sensu lato and tick-borne encephalitis virus (TBEV) antibodies among forestry workers in northern France. We compared seroprevalence by geographical area and assessed factors associated with seropositivity.
MethodsBetween 2019 and 2020, we conducted a randomised cross-sectional seroprevalence survey. Borrelia burgdorferi sl seropositivity was defined as positive ELISA and positive or equivocal result in western blot. Seropositivity for TBEV was defined as positive result from two ELISA tests, confirmed by serum neutralisation. We calculated weighted seroprevalence and adjusted prevalence ratios to determine association between potential risk factors and seropositivity.
ResultsA total of 1,778 forestry workers participated. Seroprevalence for B. burgdorferi sl was 15.5% (95% confidence interval (CI): 13.9–17.3), 3.5 times higher in the eastern regions than in the western and increased with seniority and with weekly time in a forest environment. Seroprevalence was 2.5 times higher in forestry workers reporting a tick bite during past years and reporting usually not removing ticks rapidly. Seroprevalence for TBEV was 0.14% (95% CI: 0.05–0.42).
ConclusionWe assessed for the first time seroprevalence of B. burgdorferi sl and TBEV antibodies among forestry workers in northern France. These results will be used, together with data on LB and tick-borne encephalitis (TBE) incidence and on exposure to tick-bites, to target prevention programmes.
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The COVID-19 pandemic in Greenland, epidemic features and impact of early strict measures, March 2020 to June 2022
BackgroundThe COVID-19 pandemic was of major concern in Greenland. There was a high possibility of rapid transmission in settlements, and an increased risk of morbidity and mortality because of comorbidities in the population and limited access to specialised healthcare in remote areas.
AimTo describe the epidemiology of the COVID-19 pandemic in Greenland and evaluate the effects of a strict COVID-19 strategy until risk groups were immunised.
MethodsWe studied the epidemiology during March 2020 to June 2022. We describe the non-pharmaceutical interventions (NPIs), PCR-confirmed COVID-19 cases and vaccination coverage with data from the registries of the Greenlandic health authority.
ResultsWe found 21,419 confirmed cases per 100,000 inhabitants (54% female, 46% male), 342 per 100,000 were hospitalised and 16 per 100,000 were admitted to the intensive care unit. The COVID-19 mortality rate was 39 per 100,000, all those affected were aged above 65 years. No excess overall mortality was observed. The vaccination coverage by June 2022 was 71.67 and 41% for one, two and three doses, respectively.
ConclusionSARS-CoV-2 circulation in Greenland was low, given strict restrictions until all eligible inhabitants had been offered immunisation. The main impact of the pandemic was from May 2021 onwards with increasing numbers of confirmed cases. This occurred after introduction of the vaccine programme, which may have had an influence on the severity of the associated morbidity and mortality experienced. Halting community transmission of SARS-CoV-2 with NPIs until the majority of the population had been immunised was a successful strategy in Greenland.
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Influenza transmission during COVID-19 measures downscaling in Greece, August 2022: evidence for the need of continuous integrated surveillance of respiratory viruses
After the near absence of influenza and other respiratory viruses during the first 2 years of the COVID-19 pandemic, an increased activity of mainly influenza A(H3N2) was detected at the beginning of August 2022 in Greece on three islands. Of 33 cases with respiratory symptoms testing negative for SARS-CoV-2 with rapid antigen tests, 24 were positive for influenza: 20 as A(H3N2) subtype and four as A(H1N1)pdm09 subtype. Phylogenetic analysis of selected samples from both subtypes was performed and they fell into clusters within subclades that included the 2022/23 vaccine strains. Our data suggest that influenza can be transmitted even in the presence of another highly infectious pathogen, such as SARS-CoV-2, with a similar transmission mode. We highlight the need for implementing changes in the current influenza surveillance and suggest a move from seasonal to continuous surveillance, especially in areas with a high number of tourists. Year-round surveillance would allow for a timelier start of vaccination campaigns and antiviral drugs procurement processes.
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SARS-CoV-2 in lions, gorillas and zookeepers in the Rotterdam Zoo, the Netherlands, a One Health investigation, November 2021
In November 2021, seven western lowland gorillas and four Asiatic lions were diagnosed with COVID-19 at Rotterdam Zoo. An outbreak investigation was undertaken to determine the source and extent of the outbreak and to identify possible transmission routes. Interviews were conducted with staff to identify human and animal contacts and cases, compliance with personal protective equipment (PPE) and potential transmission routes. Human and animal contacts and other animal species suspected to be susceptible to SARS-CoV-2 were tested for SARS-CoV-2 RNA. Positive samples were subjected to sequencing. All the gorillas and lions that could be tested (3/7 and 2/4, respectively) were RT-PCR positive between 12 November and 10 December 2021. No other animal species were SARS-CoV-2 RNA positive. Forty direct and indirect human contacts were identified. Two direct contacts tested RT-PCR positive 10 days after the first COVID-19 symptoms in animals. The zookeepers’ viral genome sequences clustered with those of gorillas and lions. Personal protective equipment compliance was suboptimal at instances. Findings confirm transmission of SARS-CoV-2 among animals and between humans and animals but source and directionality could not be established. Zookeepers were the most likely source and should have periodic PPE training. Sick animals should promptly be tested and isolated/quarantined.
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COVID-19 vaccine effectiveness against symptomatic infection and hospitalisation in Belgium, July 2021 to May 2022
BackgroundThe Belgian COVID-19 vaccination campaign aimed to reduce disease spread and severity.
AimWe estimated SARS-CoV-2 variant-specific vaccine effectiveness against symptomatic infection (VEi) and hospitalisation (VEh), given time since vaccination and prior infection.
MethodsNationwide healthcare records from July 2021 to May 2022 on testing and vaccination were combined with a clinical hospital survey. We used a test-negative design and proportional hazard regression to estimate VEi and VEh, controlling for prior infection, time since vaccination, age, sex, residence and calendar week of sampling.
ResultsWe included 1,932,546 symptomatic individuals, of whom 734,115 tested positive. VEi against Delta waned from an initial estimate of 80% (95% confidence interval (CI): 80–81) to 55% (95% CI: 54–55) 100–150 days after the primary vaccination course. Booster vaccination increased initial VEi to 85% (95% CI: 84–85). Against Omicron, an initial VEi of 33% (95% CI: 30–36) waned to 17% (95% CI: 15–18), while booster vaccination increased VEi to 50% (95% CI: 49–50), which waned to 20% (95% CI: 19–21) 100–150 days after vaccination. Initial VEh for booster vaccination decreased from 96% (95% CI: 95–96) against Delta to 87% (95% CI: 86–89) against Omicron. VEh against Omicron waned to 73% (95% CI: 71–75) 100–150 days after booster vaccination. While recent prior infections conferred higher protection, infections occurring before 2021 remained associated with significant risk reduction against symptomatic infection. Vaccination and prior infection outperformed vaccination or prior infection only.
ConclusionWe report waning and a significant decrease in VEi and VEh from Delta to Omicron-dominant periods. Booster vaccination and prior infection attenuated these effects.
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Enhanced surveillance of hospitalised COVID-19 patients in Europe: I-MOVE-COVID-19 surveillance network, February 2020 to December 2021
BackgroundIn early 2020, the I-MOVE-COVID-19 hospital surveillance system was adapted from an existing influenza surveillance system to include hospitalised COVID-19 cases.
AimTo describe trends in the demographic and clinical characteristics of hospitalised COVID-19 cases across Europe during the first 2 years of the pandemic, and to identify associations between sex, age and chronic conditions with admission to intensive care or high dependency units (ICU/HDU) and in-hospital mortality.
MethodsWe pooled pseudonymised data from all hospitalised COVID-19 cases in 11 surveillance sites in nine European countries, collected between 1 February 2020 and 31 December 2021. Associations between sex, age and chronic conditions, with ICU/HDU admission and in-hospital mortality were examined using Pearson’s chi-squared test, and crude odds ratio (OR) estimates with respective 95% confidence intervals (CI).
ResultsOf 25,971 hospitalised COVID-19 cases, 55% were male, 35% were 75 years or older and 90% had a chronic underlying condition. Patients with two or more chronic underlying conditions were significantly more likely to die in-hospital from COVID-19 (OR: 10.84; 95% CI: 8.30–14.16) than those without a chronic condition.
ConclusionThe surveillance demonstrated that males, those 75 years or older and those with chronic conditions were at greater risk of in-hospital death. Over the surveillance period, outcomes tended to improve, likely because of vaccinations. This surveillance has laid the groundwork for further research studies investigating the risk factors of hospitalised COVID-19 cases and vaccine effectiveness.
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Estimated protection against COVID-19 based on predicted neutralisation titres from multiple antibody measurements in a longitudinal cohort, France, April 2020 to November 2021
Tom Woudenberg , Laurie Pinaud , Laura Garcia , Laura Tondeur , Stéphane Pelleau , Alix De Thoisy , Françoise Donnadieu , Marija Backovic , Mikaël Attia , Nathanael Hozé , Cécile Duru , Aymar Davy Koffi , Sandrine Castelain , Marie-Noelle Ungeheuer , Sandrine Fernandes Pellerin , Delphine Planas , Timothée Bruel , Simon Cauchemez , Olivier Schwartz , Arnaud Fontanet and Michael WhiteBackgroundThe risk of SARS-CoV-2 (re-)infection remains present given waning of vaccine-induced and infection-acquired immunity, and ongoing circulation of new variants.
AimTo develop a method that predicts virus neutralisation and disease protection based on variant-specific antibody measurements to SARS-CoV-2 antigens.
MethodsTo correlate antibody and neutralisation titres, we collected 304 serum samples from individuals with either vaccine-induced or infection-acquired SARS-CoV-2 immunity. Using the association between antibody and neutralisation titres, we developed a prediction model for SARS-CoV-2-specific neutralisation titres. From predicted neutralising titres, we inferred protection estimates to symptomatic and severe COVID-19 using previously described relationships between neutralisation titres and protection estimates. We estimated population immunity in a French longitudinal cohort of 905 individuals followed from April 2020 to November 2021.
ResultsWe demonstrated a strong correlation between anti-SARS-CoV-2 antibodies measured using a low cost high-throughput assay and antibody response capacity to neutralise live virus. Participants with a single vaccination or immunity caused by infection were especially vulnerable to symptomatic or severe COVID-19. While the median reduced risk of COVID-19 from Delta variant infection in participants with three vaccinations was 96% (IQR: 94–98), median reduced risk among participants with infection-acquired immunity was only 42% (IQR: 22–66).
ConclusionOur results are consistent with data from vaccine effectiveness studies, indicating the robustness of our approach. Our multiplex serological assay can be readily adapted to study new variants and provides a framework for development of an assay that would include protection estimates.
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Patterns of SARS-CoV-2 circulation revealed by a nationwide sewage surveillance programme, the Netherlands, August 2020 to February 2022
BackgroundSurveillance of SARS-CoV-2 in wastewater offers a near real-time tool to track circulation of SARS-CoV-2 at a local scale. However, individual measurements of SARS-CoV-2 in sewage are noisy, inherently variable and can be left-censored.
AimWe aimed to infer latent virus loads in a comprehensive sewage surveillance programme that includes all sewage treatment plants (STPs) in the Netherlands and covers 99.6% of the Dutch population.
MethodsWe applied a multilevel Bayesian penalised spline model to estimate time- and STP-specific virus loads based on water flow-adjusted SARS-CoV-2 qRT-PCR data for one to four sewage samples per week for each of the more than 300 STPs.
ResultsThe model captured the epidemic upsurges and downturns in the Netherlands, despite substantial day-to-day variation in the measurements. Estimated STP virus loads varied by more than two orders of magnitude, from ca 1012 virus particles per 100,000 persons per day in the epidemic trough in August 2020 to almost 1015 per 100,000 in many STPs in January 2022. The timing of epidemics at the local level was slightly shifted between STPs and municipalities, which resulted in less pronounced peaks and troughs at the national level.
ConclusionAlthough substantial day-to-day variation is observed in virus load measurements, wastewater-based surveillance of SARS-CoV-2 that is performed at high sampling frequency can track long-term progression of an epidemic at a local scale in near real time.
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Rare cases of Guillain-Barré syndrome after COVID-19 vaccination, Germany, December 2020 to August 2021
More LessBackgroundGuillain-Barré syndrome (GBS) has been associated with vaccination against COVID-19.
AimWe aimed to compare clinical characteristics and analyse excess GBS cases following administration of different COVID-19 and influenza vaccines in Germany versus the expected numbers estimated from pre-pandemic background incidence rates.
MethodsWe analysed safety surveillance data reported to the German national competent authority between 27 December 2020 and 31 August 2021. GBS cases were validated according to Brighton Collaboration (BC) criteria. We conducted observed vs expected (OvE) analyses on cases fulfilling BC criteria levels 1 to 4 for all four European Medicines Agency-approved COVID-19 vaccines and for influenza vaccines.
ResultsA total of 214 GBS cases after COVID-19 vaccination had been reported, of whom 156 were eligible for further analysis. Standardised morbidity ratio estimates 3–42 days after vaccination were 0.34 (95% confidence interval (CI): 0.25–0.44) for Comirnaty, 0.38 (95% CI: 0.15–0.79) for Spikevax, 3.10 (95% CI: 2.44–3.88) for Vaxzevria, 4.16 (95% CI: 2.64–6.24) for COVID-19 Vaccine Janssen and 0.60 (95% CI: 0.35–0.94) for influenza vaccines. Bilateral facial paresis was reported in 19.7% and 26.1% of the 156 GBS cases following vaccination with Vaxzevria and COVID-19 Vaccine Janssen, respectively, and only in 6% of cases exposed to Comirnaty.
ConclusionThree and four times more GBS cases than expected were reported after vaccination with Vaxzevria and COVID-19 Vaccine Janssen, respectively, therefore GBS might be an adverse event of vector-based vaccines. Bifacial paresis was more common in cases with GBS following vaccination with vector-based than mRNA COVID-19 vaccines.
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Assessing the robustness of COVID-19 vaccine efficacy trials: systematic review and meta-analysis, January 2023
BackgroundVaccines play a crucial role in the response to COVID-19 and their efficacy is thus of great importance.
AimTo assess the robustness of COVID-19 vaccine efficacy (VE) trial results using the fragility index (FI) and fragility quotient (FQ) methodology.
MethodsWe conducted a Cochrane and PRISMA-compliant systematic review and meta-analysis of COVID-19 VE trials published worldwide until 22 January 2023. We calculated the FI and FQ for all included studies and assessed their associations with selected trial characteristics using Wilcoxon rank sum tests and Kruskal–Wallis H tests. Spearman correlation coefficients and scatter plots were used to quantify the strength of correlation of FIs and FQs with trial characteristics.
ResultsOf 6,032 screened records, we included 40 trials with 54 primary outcomes, comprising 909,404 participants with a median sample size per outcome of 13,993 (interquartile range (IQR): 8,534–25,519). The median FI and FQ was 62 (IQR: 22–123) and 0.50% (IQR: 0.24–0.92), respectively. FIs were positively associated with sample size (p < 0.001), and FQs were positively associated with type of blinding (p = 0.023). The Spearman correlation coefficient for FI with sample size was moderately strong (0.607), and weakly positive for FI and FQ with VE (0.138 and 0.161, respectively).
ConclusionsThis was the largest study on trial robustness to date. Robustness of COVID-19 VE trials increased with sample size and varied considerably across several other important trial characteristics. The FI and FQ are valuable complementary parameters for the interpretation of trial results and should be reported alongside established trial outcome measures.
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Emergence, spread and characterisation of the SARS-CoV-2 variant B.1.640 circulating in France, October 2021 to February 2022
BackgroundSuccessive epidemic waves of COVID-19 illustrated the potential of SARS-CoV-2 variants to reshape the pandemic. Detecting and characterising emerging variants is essential to evaluate their public health impact and guide implementation of adapted control measures.
AimTo describe the detection of emerging variant, B.1.640, in France through genomic surveillance and present investigations performed to inform public health decisions.
MethodsIdentification and monitoring of SARS-CoV-2 variant B.1.640 was achieved through the French genomic surveillance system, producing 1,009 sequences. Additional investigation of 272 B.1.640-infected cases was performed between October 2021 and January 2022 using a standardised questionnaire and comparing with Omicron variant-infected cases.
ResultsB.1.640 was identified in early October 2021 in a school cluster in Bretagne, later spreading throughout France. B.1.640 was detected at low levels at the end of SARS-CoV-2 Delta variant’s dominance and progressively disappeared after the emergence of the Omicron (BA.1) variant. A high proportion of investigated B.1.640 cases were children aged under 14 (14%) and people over 60 (27%) years, because of large clusters in these age groups. B.1.640 cases reported previous SARS-CoV-2 infection (4%), anosmia (32%) and ageusia (34%), consistent with data on pre-Omicron SARS-CoV-2 variants. Eight percent of investigated B.1.640 cases were hospitalised, with an overrepresentation of individuals aged over 60 years and with risk factors.
ConclusionEven though B.1.640 did not outcompete the Delta variant, its importation and continuous low-level spread raised concerns regarding its public health impact. The investigations informed public health decisions during the time that B.1.640 was circulating.
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Comprehensive surveillance of acute respiratory infections during the COVID-19 pandemic: a methodological approach using sentinel networks, Castilla y León, Spain, January 2020 to May 2022
BackgroundSince 1996, epidemiological surveillance of acute respiratory infections (ARI) in Spain has been limited to seasonal influenza, respiratory syncytial virus (RSV) and potential pandemic viruses. The COVID-19 pandemic provides opportunities to adapt existing systems for extended surveillance to capture a broader range of ARI.
AimTo describe how the Influenza Sentinel Surveillance System of Castilla y León, Spain was rapidly adapted in 2020 to comprehensive sentinel surveillance for ARI, including influenza and COVID-19.
MethodsUsing principles and methods of the health sentinel network, we integrated electronic medical record data from 68 basic surveillance units, covering 2.6% of the regional population between January 2020 to May 2022. We tested sentinel and non-sentinel samples sent weekly to the laboratory network for SARS-CoV-2, influenza viruses and other respiratory pathogens. The moving epidemic method (MEM) was used to calculate epidemic thresholds.
ResultsARI incidence was estimated at 18,942 cases per 100,000 in 2020/21 and 45,223 in 2021/22, with similar seasonal fold increases by type of respiratory disease. Incidence of influenza-like illness was negligible in 2020/21 but a 5-week epidemic was detected by MEM in 2021/22. Epidemic thresholds for ARI and COVID-19 were estimated at 459.4 and 191.3 cases per 100,000 population, respectively. More than 5,000 samples were tested against a panel of respiratory viruses in 2021/22.
ConclusionExtracting data from electronic medical records reported by trained professionals, combined with a standardised microbiological information system, is a feasible and useful method to adapt influenza sentinel reports to comprehensive ARI surveillance in the post-COVID-19 era.
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Dynamics of SARS-CoV-2 seroassay sensitivity: a systematic review and modelling study
BackgroundSerological surveys have been the gold standard to estimate numbers of SARS-CoV-2 infections, the dynamics of the epidemic, and disease severity. Serological assays have decaying sensitivity with time that can bias their results, but there is a lack of guidelines to account for this phenomenon for SARS-CoV-2.
AimOur goal was to assess the sensitivity decay of seroassays for detecting SARS-CoV-2 infections, the dependence of this decay on assay characteristics, and to provide a simple method to correct for this phenomenon.
MethodsWe performed a systematic review and meta-analysis of SARS-CoV-2 serology studies. We included studies testing previously diagnosed, unvaccinated individuals, and excluded studies of cohorts highly unrepresentative of the general population (e.g. hospitalised patients).
ResultsOf the 488 screened studies, 76 studies reporting on 50 different seroassays were included in the analysis. Sensitivity decay depended strongly on the antigen and the analytic technique used by the assay, with average sensitivities ranging between 26% and 98% at 6 months after infection, depending on assay characteristics. We found that a third of the included assays departed considerably from manufacturer specifications after 6 months.
ConclusionsSeroassay sensitivity decay depends on assay characteristics, and for some types of assays, it can make manufacturer specifications highly unreliable. We provide a tool to correct for this phenomenon and to assess the risk of decay for a given assay. Our analysis can guide the design and interpretation of serosurveys for SARS-CoV-2 and other pathogens and quantify systematic biases in the existing serology literature.
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SARS-CoV-2 self-test uptake and factors associated with self-testing during Omicron BA.1 and BA.2 waves in France, January to May 2022
BackgroundFollowing the SARS-CoV-2 Omicron variant spread, the use of unsupervised antigenic rapid diagnostic tests (self-tests) increased.
AimThis study aimed to measure self-test uptake and factors associated with self-testing.
MethodsIn this cross-sectional study from 20 January to 2 May 2022, the case series from a case–control study on factors associated with SARS-CoV-2 infection were used to analyse self-testing habits in France. A multivariable quasi-Poisson regression was used to explore the variables associated with self-testing among symptomatic cases who were not contacts of another infected individual. The control series from the same study was used as a proxy for the self-test background rate in the non-infected population of France.
ResultsDuring the study period, 179,165 cases who tested positive through supervised tests were recruited. Of these, 64.7% had performed a self-test in the 3 days preceding this supervised test, of which 79,038 (68.2%) were positive. The most frequently reported reason for self-testing was the presence of symptoms (64.6%). Among symptomatic cases who were not aware of being contacts of another case, self-testing was positively associated with being female, higher education, household size, being a teacher and negatively associated with older age, not French by birth, healthcare-related work and immunosuppression. Among the control series, 12% self-tested during the 8 days preceding questionnaire filling, with temporal heterogeneity.
ConclusionThe analysis showed high self-test uptake in France with some inequalities which must be addressed through education and facilitated access (cost and availability) for making it a more efficient epidemic control tool.
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Effects of non-compulsory and mandatory COVID-19 interventions on travel distance and time away from home, Norway, 2021
BackgroundGiven the societal, economic and health costs of COVID-19 non-pharmaceutical interventions (NPI), it is important to assess their effects. Human mobility serves as a surrogate measure for human contacts and compliance with NPI. In Nordic countries, NPI have mostly been advised and sometimes made mandatory. It is unclear if making NPI mandatory further reduced mobility.
AimWe investigated the effect of non-compulsory and follow-up mandatory measures in major cities and rural regions on human mobility in Norway. We identified NPI categories that most affected mobility.
MethodsWe used mobile phone mobility data from the largest Norwegian operator. We analysed non-compulsory and mandatory measures with before–after and synthetic difference-in-differences approaches. By regression, we investigated the impact of different NPI on mobility.
ResultsNationally and in less populated regions, time travelled, but not distance, decreased after follow-up mandatory measures. In urban areas, however, distance decreased after follow-up mandates, and the reduction exceeded the decrease after initial non-compulsory measures. Stricter metre rules, gyms reopening, and restaurants and shops reopening were significantly associated with changes in mobility.
ConclusionOverall, distance travelled from home decreased after non-compulsory measures, and in urban areas, distance further decreased after follow-up mandates. Time travelled reduced more after mandates than after non-compulsory measures for all regions and interventions. Stricter distancing and reopening of gyms, restaurants and shops were associated with changes in mobility.
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COVID-19 outbreaks among crew on commercial ships at the Port of Rotterdam, the Netherlands, 2020 to 2021
BackgroundDuring the COVID-19 pandemic, international shipping activity was disrupted as movement of people and goods was restricted. The Port of Rotterdam, the largest port in Europe, remained operational throughout.
AimWe describe the burden of COVID-19 among crew on sea-going vessels at the port and recommend improvements in future infectious disease event notification and response at commercial ports.
MethodsSuspected COVID-19 cases on sea-going vessels were notified to port authorities and public health (PH) authorities pre-arrival via the Maritime Declaration of Health. We linked data from port and PH information systems between 1 January 2020 and 31 July 2021, derived a notification rate (NR) of COVID-19 events per arrival, and an attack rate (AR) per vessel (confirmed cases). We compared AR by vessel type (workship/tanker/cargo/passenger), during wildtype-, alpha- and delta-dominant calendar periods.
ResultsEighty-four COVID-19 events were notified on ships, involving 622 cases. The NR among 45,030 new arrivals was 173 per 100,000 impacting 1% of vessels. Events per week peaked in April 2021 and again in July 2021, when the AR was also highest. Half of all cases were notified on workships, events occurring earlier and more frequently than on other vessels.
ConclusionNotification of COVID-19 events on ships occurred infrequently, although case under-ascertainment was likely. Pre-agreed protocols for data-sharing between stakeholders locally and across Europe would facilitate more efficient pandemic response. Public health access to specimens for sequencing and environmental sampling would give greater insight into viral spread on ships.
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