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Application of the screening method for estimating COVID-19 vaccine effectiveness using routine surveillance data: Germany’s experience during the COVID-19 pandemic, July 2021 to March 2023
More LessThe screening method represents a simple, quick, and practical tool for estimating vaccine effectiveness (VE) using routine disease surveillance and vaccine coverage data, even if these data cannot be linked. In Germany, where notification data, laboratory testing data, and vaccine coverage data cannot be linked due to strict data protection requirements, the screening method was used to assess COVID-19 VE continuously between July 2021 and March 2023. During this period, when Delta and Omicron variants circulated, VE estimates were produced in real-time for different age groups and clinical outcomes. Here we describe the country’s overall positive experience using the screening method, including its strengths and limitations, and provide practical guidance regarding a few issues, such as case definition stringency, testing behaviour, and data stratification, that require careful consideration during data analysis and the interpretation of the results.
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Wastewater-based reproduction numbers and projections of COVID-19 cases in three areas in Japan, November 2021 to December 2022
BackgroundWastewater surveillance has expanded globally as a means to monitor spread of infectious diseases. An inherent challenge is substantial noise and bias in wastewater data because of the sampling and quantification process, limiting the applicability of wastewater surveillance as a monitoring tool.
AimTo present an analytical framework for capturing the growth trend of circulating infections from wastewater data and conducting scenario analyses to guide policy decisions.
MethodsWe developed a mathematical model for translating the observed SARS-CoV-2 viral load in wastewater into effective reproduction numbers. We used an extended Kalman filter to infer underlying transmissions by smoothing out observational noise. We also illustrated the impact of different countermeasures such as expanded vaccinations and non-pharmaceutical interventions on the projected number of cases using three study areas in Japan during 2021–22 as an example.
ResultsObserved notified cases were matched with the range of cases estimated by our approach with wastewater data only, across different study areas and virus quantification methods, especially when the disease prevalence was high. Estimated reproduction numbers derived from wastewater data were consistent with notification-based reproduction numbers. Our projections showed that a 10–20% increase in vaccination coverage or a 10% reduction in contact rate may suffice to initiate a declining trend in study areas.
ConclusionOur study demonstrates how wastewater data can be used to track reproduction numbers and perform scenario modelling to inform policy decisions. The proposed framework complements conventional clinical surveillance, especially when reliable and timely epidemiological data are not available.
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Bias in vaccine effectiveness studies of clinically severe outcomes that are measured with low specificity: the example of COVID-19-related hospitalisation
More LessMany vaccine effectiveness (VE) analyses of severe disease outcomes such as hospitalisation and death include ‘false’ cases that are not actually caused by the infection or disease under study. While the inclusion of such false cases inflate outcome rates in both vaccinated and unvaccinated populations, it is less obvious how they affect estimates of VE. Illustrating the main points through simple examples, this article shows how VE is underestimated when false cases are included as outcomes. Depending how the outcome indicator is defined, estimates of VE against severe disease outcomes, whose definition allows for the inclusion of false cases, will be biased downwards and may in certain circumstances approximate the same level as the VE against infection. The bias is particularly pronounced for vaccines that offer high levels of protection against severe disease outcomes but poor protection against infection. Analysing outcomes that are measured with low sensitivity generally does not cause bias in VE studies; defining outcome indicators that minimise the number of false cases rather than the number of missed cases is preferable in VE studies.
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Effectiveness of the adapted bivalent mRNA COVID-19 vaccines against hospitalisation in individuals aged ≥ 60 years during the Omicron XBB lineage-predominant period: VEBIS SARI VE network, Europe, February to August, 2023
Liliana Antunes , Clara Mazagatos , Iván Martínez-Baz , Verónica Gomez , Maria-Louise Borg , Goranka Petrović , Róisín Duffy , François E Dufrasne , Ralf Dürrwald , Mihaela Lazar , Ligita Jancoriene , Beatrix Oroszi , Petr Husa , Jennifer Howard , Aryse Melo , Francisco Pozo , Gloria Pérez-Gimeno , Jesús Castilla , Ausenda Machado , Aušra Džiugytė , Svjetlana Karabuva , Margaret Fitzgerald , Sébastien Fierens , Kristin Tolksdorf , Silvia-Odette Popovici , Auksė Mickienė , Gergő Túri , Lenka Součková , Nathalie Nicolay , Angela MC Rose and on behalf of the European Hospital Vaccine Effectiveness GroupWe conducted a multicentre hospital-based test-negative case–control study to measure the effectiveness of adapted bivalent COVID-19 mRNA vaccines against PCR-confirmed SARS-CoV-2 infection during the Omicron XBB lineage-predominant period in patients aged ≥ 60 years with severe acute respiratory infection from five countries in Europe. Bivalent vaccines provided short-term additional protection compared with those vaccinated > 6 months before the campaign: from 80% (95% CI: 50 to 94) for 14–89 days post-vaccination, 15% (95% CI: −12 to 35) at 90–179 days, and lower to no effect thereafter.
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Humoral immune escape by current SARS-CoV-2 variants BA.2.86 and JN.1, December 2023
Variant BA.2.86 and its descendant, JN.1, of SARS-CoV-2 are rising in incidence across Europe and globally. We isolated recent JN.1, BA.2.86, EG.5, XBB.1.5 and earlier variants. We tested live virus neutralisation of sera taken in September 2023 from vaccinated and exposed healthy persons (n = 39). We found clear neutralisation escape against recent variants but no specific pronounced escape for BA.2.86 or JN.1. Neutralisation escape corresponds to recent variant predominance but may not be causative of the recent upsurge in JN.1 incidence.
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Impact of sex and gender on post-COVID-19 syndrome, Switzerland, 2020
Caroline E Gebhard , Claudia Sütsch , Pimrapat Gebert , Bianca Gysi , Susan Bengs , Atanas Todorov , Manja Deforth , Philipp K Buehler , Alexander Meisel , Reto A Schuepbach , Annelies S Zinkernagel , Silvio D Brugger , Claudio Acevedo , Dimitri Patriki , Benedikt Wiggli , Jürg H Beer , Andrée Friedl , Raphael Twerenbold , Gabriela M Kuster , Hans Pargger , Sarah Tschudin-Sutter , Joerg C Schefold , Thibaud Spinetti , Chiara Henze , Mina Pasqualini , Dominik F Sager , Lilian Mayrhofer , Mirjam Grieder , Janna Tontsch , Fabian C Franzeck , Pedro D Wendel Garcia , Daniel A Hofmaenner , Thomas Scheier , Jan Bartussek , Ahmed Haider , Muriel Grämer , Nidaa Mikail , Alexia Rossi , Núria Zellweger , Petra Opić , Angela Portmann , Roland von Känel , Aju P Pazhenkottil , Michael Messerli , Ronny R Buechel , Philipp A Kaufmann , Valerie Treyer , Martin Siegemund , Ulrike Held , Vera Regitz-Zagrosek and Catherine GebhardBackgroundWomen are overrepresented among individuals with post-acute sequelae of SARS-CoV-2 infection (PASC). Biological (sex) as well as sociocultural (gender) differences between women and men might account for this imbalance, yet their impact on PASC is unknown.
AimWe assessed the impact of sex and gender on PASC in a Swiss population.
MethodOur multicentre prospective cohort study included 2,856 (46% women, mean age 44.2 ± 16.8 years) outpatients and hospitalised patients with PCR-confirmed SARS-CoV-2 infection.
ResultsAmong those who remained outpatients during their first infection, women reported persisting symptoms more often than men (40.5% vs 25.5% of men; p < 0.001). This sex difference was absent in hospitalised patients. In a crude analysis, both female biological sex (RR = 1.59; 95% CI: 1.41–1.79; p < 0.001) and a score summarising gendered sociocultural variables (RR = 1.05; 95% CI: 1.03–1.07; p < 0.001) were significantly associated with PASC. Following multivariable adjustment, biological female sex (RR = 0.96; 95% CI: 0.74–1.25; p = 0.763) was outperformed by feminine gender-related factors such as a higher stress level (RR = 1.04; 95% CI: 1.01–1.06; p = 0.003), lower education (RR = 1.16; 95% CI: 1.03–1.30; p = 0.011), being female and living alone (RR = 1.91; 95% CI: 1.29–2.83; p = 0.001) or being male and earning the highest income in the household (RR = 0.76; 95% CI: 0.60–0.97; p = 0.030).
ConclusionSpecific sociocultural parameters that differ in prevalence between women and men, or imply a unique risk for women, are predictors of PASC and may explain, at least in part, the higher incidence of PASC in women. Once patients are hospitalised during acute infection, sex differences in PASC are no longer evident.
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Early COVID-19 vaccine effectiveness of XBB.1.5 vaccine against hospitalisation and admission to intensive care, the Netherlands, 9 October to 5 December 2023
We present early vaccine effectiveness (VE) estimates of the 2023 seasonal COVID-19 XBB.1.5 vaccine against COVID-19 hospitalisation and admission to an intensive care unit (ICU) in previously vaccinated adults ≥ 60 years in the Netherlands. We compared vaccination status of 2,050 hospitalisations including 92 ICU admissions with age group-, sex-, region- and date-specific population vaccination coverage between 9 October and 5 December 2023. VE against hospitalisation was 70.7% (95% CI: 66.6–74.3), VE against ICU admission was 73.3% (95% CI: 42.2–87.6).
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Relative vaccine effectiveness against COVID-19 hospitalisation in persons aged ≥ 65 years: results from a VEBIS network, Europe, October 2021 to July 2023
Mario Fontán-Vela , Esther Kissling , Nathalie Nicolay , Toon Braeye , Izaak Van Evercooren , Christian Holm Hansen , Hanne-Dorthe Emborg , Massimo Fabiani , Alberto Mateo-Urdiales , Ala'a AlKerwi , Susanne Schmitz , Jesús Castilla , Iván Martínez-Baz , Brechje de Gier , Susan Hahné , Hinta Meijerink , Jostein Starrfelt , Baltazar Nunes , Constantino Caetano , Tarik Derrough , Anthony Nardone , Susana Monge and VEBIS-Lot4 working groupTo monitor relative vaccine effectiveness (rVE) against COVID-19-related hospitalisation of the first, second and third COVID-19 booster (vs complete primary vaccination), we performed monthly Cox regression models using retrospective cohorts constructed from electronic health registries in eight European countries, October 2021–July 2023. Within 12 weeks of administration, each booster showed high rVE (≥ 70% for second and third boosters). However, as of July 2023, most of the relative benefit has waned, particularly in persons ≥ 80-years-old, while some protection remained in 65–79-year-olds.
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Impact of the COVID-19 pandemic on prevalence of highly resistant microorganisms in hospitalised patients in the Netherlands, March 2020 to August 2022
BackgroundThe COVID-19 pandemic resulted in adaptation in infection control measures, increased patient transfer, high occupancy of intensive cares, downscaling of non-urgent medical procedures and decreased travelling.
AimTo gain insight in the influence of these changes on antimicrobial resistance (AMR) prevalence in the Netherlands, a country with a low AMR prevalence, we estimated changes in demographics and prevalence of six highly resistant microorganisms (HRMO) in hospitalised patients in the Netherlands during COVID-19 waves (March–June 2020, October 2020–June 2021, October 2021–May 2022 and June–August 2022) and interwaves (July–September 2020 and July–September 2021) compared with pre-COVID-19 (March 2019–February 2020).
MethodsWe investigated data on routine bacteriology cultures of hospitalised patients, obtained from 37 clinical microbiological laboratories participating in the national AMR surveillance. Demographic characteristics and HRMO prevalence were calculated as proportions and rates per 10,000 hospital admissions.
ResultsAlthough no significant persistent changes in HRMO prevalence were detected, some relevant non-significant patterns were recognised in intensive care units. Compared with pre-COVID-19 we found a tendency towards higher prevalence of meticillin-resistant Staphylococcus aureus during waves and lower prevalence of multidrug-resistant Pseudomonas aeruginosa during interwaves. Additionally, during the first three waves, we observed significantly higher proportions and rates of cultures with Enterococcus faecium (pooled 10% vs 6% and 240 vs 120 per 10,000 admissions) and coagulase-negative Staphylococci (pooled 21% vs 14% and 500 vs 252 per 10,000 admissions) compared with pre-COVID-19.
ConclusionWe observed no substantial changes in HRMO prevalence in hospitalised patients during the COVID-19 pandemic.
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Relative vaccine effectiveness of mRNA COVID-19 boosters in people aged at least 75 years during the spring-summer (monovalent vaccine) and autumn-winter (bivalent vaccine) booster campaigns: a prospective test negative case–control study, United Kingdom, 2022
BackgroundUnderstanding the relative vaccine effectiveness (rVE) of new COVID-19 vaccine formulations against SARS-CoV-2 infection is a public health priority. A precise analysis of the rVE of monovalent and bivalent boosters given during the 2022 spring-summer and autumn-winter campaigns, respectively, in a defined population remains of interest.
AimWe assessed rVE against hospitalisation for the spring-summer (fourth vs third monovalent mRNA vaccine doses) and autumn-winter (fifth BA.1/ancestral bivalent vs fourth monovalent mRNA vaccine dose) boosters.
MethodsWe performed a prospective single-centre test-negative design case–control study in ≥ 75-year-old people hospitalised with COVID-19 or other acute respiratory disease. We conducted regression analyses controlling for age, sex, socioeconomic status, patient comorbidities, community SARS-CoV-2 prevalence, vaccine brand and time between baseline dose and hospitalisation.
ResultsWe included 682 controls and 182 cases in the spring-summer booster analysis and 572 controls and 152 cases in the autumn-winter booster analysis. A monovalent mRNA COVID-19 vaccine as fourth dose showed 46.6% rVE (95% confidence interval (CI): 13.9–67.1) vs those not fully boosted. A bivalent mRNA COVID-19 vaccine as fifth dose had 46.7% rVE (95% CI: 18.0–65.1), compared with a fourth monovalent mRNA COVID-19 vaccine dose.
ConclusionsBoth fourth monovalent and fifth BA.1/ancestral mRNA bivalent COVID-19 vaccine doses demonstrated benefit as a booster in older adults. Bivalent mRNA boosters offered similar protection against hospitalisation with Omicron infection to monovalent mRNA boosters given earlier in the year. These findings support immunisation programmes in several European countries that advised the use of BA.1/ancestral bivalent booster doses.
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Effectiveness of bivalent COVID-19 boosters against COVID-19 mortality in people aged 65 years and older, Australia, November 2022 to May 2023
More LessWe followed 4,081,257 Australian adults aged ≥ 65 years between November 2022 and May 2023 for COVID-19-specific mortality, when recombinant SARS-CoV-2 Omicron lineages (predominantly XB and XBB) as well as BA.2.75 were circulating. Compared with a COVID-19 booster targeting ancestral SARS-CoV-2 given > 180 days earlier, the relative vaccine effectiveness against COVID-19 death of a bivalent (ancestral/BA.1 or ancestral/BA.4-5) booster given 8 to 90 days earlier was 66.0% (95%CI: 57.6 to 72.2%) and that of a monovalent ancestral booster given 8 to 90 days earlier was 44.7% (95%CI: 23.9 to 59.7%).
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Vaccine effectiveness against COVID-19 hospitalisation in adults (≥ 20 years) during Alpha- and Delta-dominant circulation: I-MOVE-COVID-19 and VEBIS SARI VE networks, Europe, 2021
Angela MC Rose , Nathalie Nicolay , Virginia Sandonis Martín , Clara Mazagatos , Goranka Petrović , F Annabel Niessen , Ausenda Machado , Odile Launay , Sarah Denayer , Lucie Seyler , Joaquin Baruch , Cristina Burgui , Isabela I Loghin , Lisa Domegan , Roberta Vaikutytė , Petr Husa , George Panagiotakopoulos , Nassera Aouali , Ralf Dürrwald , Jennifer Howard , Francisco Pozo , Bartolomé Sastre-Palou , Diana Nonković , Mirjam J Knol , Irina Kislaya , Liem binh Luong Nguyen , Nathalie Bossuyt , Thomas Demuyser , Aušra Džiugytė , Iván Martínez-Baz , Corneliu Popescu , Róisín Duffy , Monika Kuliešė , Lenka Součková , Stella Michelaki , Marc Simon , Janine Reiche , María Teresa Otero-Barrós , Zvjezdana Lovrić Makarić , Patricia CJL Bruijning-Verhagen , Verónica Gomez , Zineb Lesieur , Cyril Barbezange , Els Van Nedervelde , Maria-Louise Borg , Jesús Castilla , Mihaela Lazar , Joan O’Donnell , Indrė Jonikaitė , Regina Demlová , Marina Amerali , Gil Wirtz , Kristin Tolksdorf , Marta Valenciano , Sabrina Bacci , Esther Kissling , I-MOVE-COVID-19 hospital study team and VEBIS hospital study teamIntroductionTwo large multicentre European hospital networks have estimated vaccine effectiveness (VE) against COVID-19 since 2021.
AimWe aimed to measure VE against PCR-confirmed SARS-CoV-2 in hospitalised severe acute respiratory illness (SARI) patients ≥ 20 years, combining data from these networks during Alpha (March–June)- and Delta (June–December)-dominant periods, 2021.
MethodsForty-six participating hospitals across 14 countries follow a similar generic protocol using the test-negative case–control design. We defined complete primary series vaccination (PSV) as two doses of a two-dose or one of a single-dose vaccine ≥ 14 days before onset.
ResultsWe included 1,087 cases (538 controls) and 1,669 cases (1,442 controls) in the Alpha- and Delta-dominant periods, respectively. During the Alpha period, VE against hospitalisation with SARS-CoV2 for complete Comirnaty PSV was 85% (95% CI: 69–92) overall and 75% (95% CI: 42–90) in those aged ≥ 80 years. During the Delta period, among SARI patients ≥ 20 years with symptom onset ≥ 150 days from last PSV dose, VE for complete Comirnaty PSV was 54% (95% CI: 18–74). Among those receiving Comirnaty PSV and mRNA booster (any product) ≥ 150 days after last PSV dose, VE was 91% (95% CI: 57–98). In time-since-vaccination analysis, complete all-product PSV VE was > 90% in those with their last dose < 90 days before onset; ≥ 70% in those 90–179 days before onset.
ConclusionsOur results from this EU multi-country hospital setting showed that VE for complete PSV alone was higher in the Alpha- than the Delta-dominant period, and addition of a first booster dose during the latter period increased VE to over 90%.
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Vaccine effectiveness against COVID-19 hospitalisation in adults (≥ 20 years) during Omicron-dominant circulation: I-MOVE-COVID-19 and VEBIS SARI VE networks, Europe, 2021 to 2022
Angela MC Rose , Nathalie Nicolay , Virginia Sandonis Martín , Clara Mazagatos , Goranka Petrović , Joaquin Baruch , Sarah Denayer , Lucie Seyler , Lisa Domegan , Odile Launay , Ausenda Machado , Cristina Burgui , Roberta Vaikutyte , F Annabel Niessen , Isabela I Loghin , Petr Husa , Nassera Aouali , George Panagiotakopoulos , Kristin Tolksdorf , Judit Krisztina Horváth , Jennifer Howard , Francisco Pozo , Virtudes Gallardo , Diana Nonković , Aušra Džiugytė , Nathalie Bossuyt , Thomas Demuyser , Róisín Duffy , Liem binh Luong Nguyen , Irina Kislaya , Iván Martínez-Baz , Giedre Gefenaite , Mirjam J Knol , Corneliu Popescu , Lenka Součková , Marc Simon , Stella Michelaki , Janine Reiche , Annamária Ferenczi , Concepción Delgado-Sanz , Zvjezdana Lovrić Makarić , John Paul Cauchi , Cyril Barbezange , Els Van Nedervelde , Joan O’Donnell , Christine Durier , Raquel Guiomar , Jesús Castilla , Indrė Jonikaite , Patricia CJL Bruijning-Verhagen , Mihaela Lazar , Regina Demlová , Gil Wirtz , Marina Amerali , Ralf Dürrwald , Mihály Pál Kunstár , Esther Kissling , Sabrina Bacci , Marta Valenciano , I-MOVE-COVID-19 hospital study team and VEBIS hospital study teamIntroductionThe I-MOVE-COVID-19 and VEBIS hospital networks have been measuring COVID-19 vaccine effectiveness (VE) in participating European countries since early 2021.
AimWe aimed to measure VE against PCR-confirmed SARS-CoV-2 in patients ≥ 20 years hospitalised with severe acute respiratory infection (SARI) from December 2021 to July 2022 (Omicron-dominant period).
MethodsIn both networks, 46 hospitals (13 countries) follow a similar test-negative case–control protocol. We defined complete primary series vaccination (PSV) and first booster dose vaccination as last dose of either vaccine received ≥ 14 days before symptom onset (stratifying first booster into received < 150 and ≥ 150 days after last PSV dose). We measured VE overall, by vaccine category/product, age group and time since first mRNA booster dose, adjusting by site as a fixed effect, and by swab date, age, sex, and presence/absence of at least one commonly collected chronic condition.
ResultsWe included 2,779 cases and 2,362 controls. The VE of all vaccine products combined against hospitalisation for laboratory-confirmed SARS-CoV-2 was 43% (95% CI: 29–54) for complete PSV (with last dose received ≥ 150 days before onset), while it was 59% (95% CI: 51–66) after addition of one booster dose. The VE was 85% (95% CI: 78–89), 70% (95% CI: 61–77) and 36% (95% CI: 17–51) for those with onset 14–59 days, 60–119 days and 120–179 days after booster vaccination, respectively.
ConclusionsOur results suggest that, during the Omicron period, observed VE against SARI hospitalisation improved with first mRNA booster dose, particularly for those having symptom onset < 120 days after first booster dose.
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Early detection of the emerging SARS-CoV-2 BA.2.86 lineage through integrated genomic surveillance of wastewater and COVID-19 cases in Sweden, weeks 31 to 38 2023
The SARS-CoV-2 BA.2.86 Omicron subvariant was first detected in wastewater in Sweden in week 31 2023, using 21 highly specific markers from the 50 investigated. We report BA.2.86’s introduction and subsequent spread to all 14 regions performing wastewater sampling, and on 70 confirmed COVID-19 cases, along with the emergence of sublineages JN.1 and JN.2. Further, we investigated two novel mutations defining the unique BA.2.86 branching in Sweden. Our integrated approach enabled variant tracking, offering evidence for well-informed public health interventions.
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Investigation of an international water polo tournament in Czechia as a potential source for early introduction of the SARS-CoV-2 Omicron variant into Belgium, Switzerland and Germany, November 2021
Christoph Rudin , Nena Bollen , Samuel L Hong , Fanny Wegner , Lida Politi , Kassiani Mellou , Caspar Geenen , Sarah Gorissen , Bruno Verhasselt , Keith Durkin , Coralie Henin , Anne-Sophie Logist , Simon Dellicour , Tobias Resa , Tanja Stadler , Piet Maes , Lize Cuypers , Emmanuel André , Adrian Egli and Guy BaeleBackgroundThe earliest recognised infections by the SARS-CoV-2 Omicron variant (Pango lineage B.1.1.529) in Belgium and Switzerland suggested a connection to an international water polo tournament, held 12–14 November 2021 in Brno, Czechia.
AimTo study the arrival and subsequent spread of the Omicron variant in Belgium and Switzerland, and understand the overall importance of this international sporting event on the number of infections in the two countries.
MethodsWe performed intensive forward and backward contact tracing in both countries, supplemented by phylogenetic investigations using virus sequences of the suspected infection chain archived in public databases.
ResultsThrough contact tracing, we identified two and one infected athletes of the Belgian and Swiss water polo teams, respectively, and subsequently also three athletes from Germany. In Belgium and Switzerland, four and three secondary infections, and three and one confirmed tertiary infections were identified. Phylogenetic investigation demonstrated that this sporting event played a role as the source of infection, but without a direct link with infections from South Africa and not as a superspreading event; the virus was found to already be circulating at that time in the countries involved.
ConclusionThe SARS-CoV-2 Omicron variant started to circulate in Europe several weeks before its identification in South Africa on 24 November 2021. Accordingly, it can be assumed that travel restrictions are usually implemented too late to prevent the spread of newly detected SARS-CoV-2 variants to other regions. Phylogenetic analysis may modify the perception of an apparently clear result of intensive contact tracing.
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PCR testing of traced contacts for SARS-CoV-2 in England, January to July 2021
BackgroundThe NHS Test and Trace (NHSTT) programme was established in May 2020 in England to deliver SARS-CoV-2 testing and contact tracing in order to identify infected individuals and reduce COVID-19 spread. To further control transmission, people identified as contacts were asked to self-isolate for 10 days and test only if they became symptomatic. From March 2021, eligibility criteria for PCR testing expanded to include asymptomatic contacts of confirmed cases.
AimTo analyse testing patterns of contacts before and after the change in testing guidance in England to assess the impact on PCR testing behaviour with respect to symptom status and contact type.
MethodsTesting and contact tracing data were extracted from the national data systems and linked. Subsequently, descriptive statistical analysis was applied to identify trends in testing behaviour.
ResultsBetween 1 January and 31 July 2021, over 5 million contacts were identified and reached by contact tracers; 42.3% took a PCR test around the time they were traced. Overall positivity rate was 44.3% and consistently higher in symptomatic (60–70%) than asymptomatic (around 20%, March–June) contacts. The proportion of tests taken by asymptomatic contacts increased over time, especially after the change in testing guidance. No link was observed between uptake of PCR tests and vaccination coverage. Fully vaccinated contacts showed lower positivity (23.8%) than those with one dose (37.2%) or unvaccinated (51.0%).
ConclusionAlmost 1 million asymptomatic contacts were tested for SARS-CoV-2, identifying 214,056 positive cases, demonstrating the value of offering PCR testing to this group.
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Epidemiology of common infectious diseases before and during the COVID-19 pandemic in Bavaria, Germany, 2016 to 2021: an analysis of routine surveillance data
More LessBackgroundUnprecedented non-pharmaceutical interventions to control the COVID-19 pandemic also had an effect on other infectious diseases.
AimWe aimed to determine their impact on transmission and diagnosis of notifiable diseases other than COVID-19 in Bavaria, Germany, in 2020 and 2021.
MethodsWe compared weekly cases of 15 notifiable infectious diseases recorded in Bavaria between 1 January 2016 and 31 December 2021 in time series analyses, median age and time-to-diagnosis using Wilcoxon rank sum test and hospitalisation rates using univariable logistic regression during three time periods: pre-pandemic (weeks 1 2016–9 2020), pandemic years 1 (weeks 10–52 2020) and 2 (2021).
ResultsWeekly case numbers decreased in pandemic year 1 for all diseases assessed except influenza, Lyme disease and tick-borne encephalitis; markedly for norovirus gastroenteritis (IRR = 0.15; 95% CI: 0.12–0.20) and pertussis (IRR = 0.22; 95% CI: 0.18–0.26). In pandemic year 2, influenza (IRR = 0.04; 95% CI: 0.02–0.09) and pertussis (IRR = 0.11; 95% CI: 0.09–0.14) decreased markedly, but also chickenpox, dengue fever, Haemophilus influenzae invasive infection, hepatitis C, legionellosis, noro- and rotavirus gastroenteritis and salmonellosis. For enterohaemorrhagic Escherichia coli infections, median age decreased in pandemic years 1 and 2 (4 years, interquartile range (IQR): 1–32 and 3 years, IQR: 1–18 vs 11 years, IQR: 2–42); hospitalisation proportions increased in pandemic year 1 (OR = 1.60; 95% CI: 1.08–2.34).
ConclusionReductions for various infectious diseases and changes in case characteristics in 2020 and 2021 indicate reduced transmission of notifiable diseases other than COVID-19 due to interventions and under-detection.
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Implementation of a broad public health approach to COVID-19 in Sweden, January 2020 to May 2022
In 2020, the world had to adapt to a pandemic caused by a then novel coronavirus. In addition to its direct impact on morbidity and mortality, the COVID-19 pandemic brought unprecedented control measures and challenges to both individuals and society. Sweden has been seen by many as an outlier in the management of the pandemic. It is therefore of special interest to document the actual management of the pandemic in Sweden during its first 2 years and how public health was affected. In the authors opinion, within the Swedish context, it has been possible to achieve a similar level of effect on mortality and morbidity through recommendations as was achieved through stringent legal measures in comparable countries. This is supported by comparisons of excess mortality that have been published. Furthermore, we see in the available data that the consequences on mental health and living habits were very limited for the majority of the population. Trust in public institutions is high in Sweden, which has been important and is part of the context that made it possible to manage a pandemic with relatively ‘soft’ measures. We acknowledge challenges in protecting certain vulnerable groups, particularly during the first and second wave.
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The value of manual backward contact tracing to control COVID-19 in practice, the Netherlands, February to March 2021: a pilot study
BackgroundContact tracing has been a key component of COVID-19 outbreak control. Backward contact tracing (BCT) aims to trace the source that infected the index case and, thereafter, the cases infected by the source. Modelling studies have suggested BCT will substantially reduce SARS-CoV-2 transmission in addition to forward contact tracing.
AimTo assess the feasibility and impact of adding BCT in practice.
MethodsWe identified COVID-19 cases who were already registered in the electronic database between 19 February and 10 March 2021 for routine contact tracing at the Public Health Service (PHS) of Rotterdam-Rijnmond, the Netherlands (pop. 1.3 million). We investigated if, through a structured questionnaire by dedicated contact tracers, we could trace additional sources and cases infected by these sources. Potential sources identified by the index were approached to trace the source’s contacts. We evaluated the number of source contacts that could be additionally quarantined.
ResultsOf 7,448 COVID-19 cases interviewed in the study period, 47% (n = 3,497) indicated a source that was already registered as a case in the PHS electronic database. A potential, not yet registered source was traced in 13% (n = 979). Backward contact tracing was possible in 62 of 979 cases, from whom an additional 133 potential sources were traced, and four were eligible for tracing of source contacts. Two additional contacts traced had to stay in quarantine for 1 day. No new COVID-19 cases were confirmed.
ConclusionsThe addition of manual BCT to control the COVID-19 pandemic did not provide added value in our study setting.
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A comparison of COVID-19 incidence rates across six European countries in 2021
International comparisons of COVID-19 incidence rates have helped gain insights into the characteristics of the disease, benchmark disease impact, shape public health measures and inform potential travel restrictions and border control measures. However, these comparisons may be biased by differences in COVID-19 surveillance systems and approaches to reporting in each country. To better understand these differences and their impact on incidence comparisons, we collected data on surveillance systems from six European countries: Belgium, England, France, Italy, Romania and Sweden. Data collected included: target testing populations, access to testing, case definitions, data entry and management and statistical approaches to incidence calculation. Average testing, incidence and contextual data were also collected. Data represented the surveillance systems as they were in mid-May 2021. Overall, important differences between surveillance systems were detected. Results showed wide variations in testing rates, access to free testing and the types of tests recorded in national databases, which may substantially limit incidence comparability. By systematically including testing information when comparing incidence rates, these comparisons may be greatly improved. New indicators incorporating testing or existing indicators such as death or hospitalisation will be important to improving international comparisons.
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