Patient-physician discordance impairs outcomes in early rheumatoid arthritis through less consistent treat-to-target implementation.

OBJECTIVES: We aimed to assess whether patient-physician discordance regarding disease activity affects T2T-implementation and clinical outcomes in rheumatoid arthritis (RA). METHODS: This was an analysis of the 2-year T2T-guided trial Care in early RA (CareRA). During year 1, DMARD escalations were mandated by the protocol when DAS28-CRP was >3.2. During year 2, treatment was at the rheumatologists' discretion. At each visit we assessed T2T-implementation, defined as escalating DMARDs if DAS28-CRP >3.2. Patient-physician discordance was defined by the discordance score (DS), a weighted difference between patient-reported and clinical/laboratory outcomes. Using generalised linear mixed models and multilevel mediation analysis, we studied the association between time-varying DS, T2T-implementation and the odds of remission (SDAI ≤3.3), physical functioning (HAQ-score), and radiographic progression at year 2. RESULTS: Over 2 years, 379 patients were assessed at 3129 follow-up visits. On 445 (14%) of these visits, DAS28-CRP was >3.2, and DMARDs were escalated in 217/445 (49%) of such cases. T2T-implementation declined over time and was consistently lower during the second year (year 1: 57-66%; year 2: 17-52%). Higher DS over time was negatively associated with remission and physical functioning at year 2, partly mediated by a lower proportion of T2T-adherent visits. No such association was found for radiographic progression. CONCLUSION: Even in a trial setting, T2T was applied on only around 50% of visits. T2T was less likely to be implemented with increasing patient-physician discordance regarding disease activity, which was in turn associated with less remission and worse functional outcome, but not with radiographic progression.

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.

New indicator for discordance between patient-reported and traditional disease activity outcomes in patients with early rheumatoid arthritis.

OBJECTIVE: To unravel disease impact in early RA by separately quantifying patient-reported (PRF), clinical (CF) and laboratory (LF) factors. We propose a new indicator, the discordance score (DS), for early identification and prediction of patient's unmet needs and of future achievement of sustained remission (SR) and RA-related quality of life (QoL). METHODS: Factor-scores obtained by factor analysis in the CareRA trial, allowed to compute DS, reflecting the difference between PRF and the mean of CF and LF. Improvement from baseline to week 104 (%) and area-under-the-curve (AUC) across time points per factor-score were calculated and compared between patients achieving/not achieving sustained (week 16-104) remission (DAS28CRP < 2.6) with ANOVA. Logistic and linear regressions were used to predict SR based on previous factor and discordance scores, and QoL at year 1 and 2 based on DS at week 16. RESULTS: PRF, CF and LF scores improved rapidly within 8 weeks. PRF improved 57%, CF 90% and LF 27%, in those achieving SR, compared with 32% (PRF: P = 0.13), 77% (CF: P < 0.001) and 9% (LF: P = 0.36) in patients not achieving SR. Patients achieving SR had an AUC of 15.7, 3.4 and 4.8 for PRF, CF and LF, respectively, compared with 33.2, 10.1 and 7.2 in participants not achieving SR (P < 0.001 for all). Early discordance was associated with later factor scores, QoL and self-efficacy. CONCLUSIONS: All factor scores improved rapidly, especially in patients achieving sustained remission. Patient-reported burden improved less. Discordance scores could help predicting the need for additional non-pharmacological interventions to achieve sustained remission and decrease disease impact.

Five-year treat-to-target outcomes after methotrexate induction therapy with or without other csDMARDs and temporary glucocorticoids for rheumatoid arthritis in the CareRA trial.

OBJECTIVES: To compare outcomes of different treatment schedules from the care in early rheumatoid arthritis (CareRA) trial over 5 years. METHODS: Patients with RA completing the 2-year CareRA randomised controlled trial were eligible for the 3-year observational CareRA-plus study. 5-year outcomes after randomisation to initial methotrexate (MTX) monotherapy with glucocorticoid bridging (COBRA-Slim) were compared with MTX step-up without glucocorticoids or conventional synthetic disease-modifying antirheumatic drug (DMARD) combinations with glucocorticoid bridging, per prognostic patient group. Disease activity (Disease Activity Score based on 28 joints calculated with C reactive protein (DAS28-CRP)) and functionality (Health Assessment Questionnaire (HAQ)) were compared between treatment arms using longitudinal models; safety and drug use were detailed. RESULTS: Of 322 eligible patients, 252 (78%) entered CareRA-plus, of which 203 (81%) completed the study. Treatments for high-risk patients resulted in comparable DAS28-CRP (p=0.539) and HAQ scores over 5 years (p=0.374). Low-risk patients starting COBRA-Slim had lower DAS28-CRP (p<0.001) and HAQ scores (p=0.041) than those starting only on MTX. At study completion, 114/203 (56%) patients never had their original DMARD therapy intensified, with comparable rates between all treatments. Safety was comparable between treatments in high-risk patients. In low-risk patients, there were 18 adverse events in 10 COBRA-Slim and 36 in 17 patients treated with initial MTX monotherapy (p=0.048). Over 5 years, 22% of patients initiated biologics, 25% took glucocorticoids for >3 months and 17% for >6 months outside the bridging period. CONCLUSIONS: All intensive treatments with glucocorticoids bridging demonstrated excellent 5 year outcomes. Initiating COBRA-Slim was comparably effective as more complex treatments for high-risk patients with early RA and more effective than initial MTX monotherapy for low-risk patients with limited need for biologics and chronic glucocorticoid use.

Having a co-morbidity predicts worse outcome in early rheumatoid arthritis despite intensive treatment: a post hoc evaluation of the pragmatic randomized controlled CareRA trial.

OBJECTIVES: To quantify the prevalence of co-morbidities in patients with early RA and determine their prognostic value for effectiveness outcomes in a randomized trial. METHODS: We included patients from the 2-year pragmatic randomized CareRA trial, who had early RA (diagnosis < 1 year), were DMARD naïve and then treated-to-target with different remission induction schemes. Prevalence of co-morbidities was registered at baseline and the Rheumatic Diseases Comorbidity Index (RDCI; range 0-9) was calculated. We tested the relation between baseline RDCI and outcomes including disease activity (DAS28-CRP), physical function (HAQ index), quality of life (SF-36 domains) and hospitalizations over 2 years, using linear mixed models or generalized estimating equations models. RESULTS: Of 379 included patients, 167 (44%) had a RDCI of minimum 1. RDCI scores of 1, 2 or ≥3 were obtained in 65 (17%), 70 (19%), and 32 (8%) participants, respectively. The most frequent co-morbidity was hypertension (22%). Patients with co-morbidities had significantly higher HAQ (ß = 0.215; 95% CI: 0.071, 0.358), DAS28-CRP (ß = 0.225; 95% CI: 0.132, 0.319) and lower SF-36 physical component summary scores (ß =-3.195; 95% CI: -4.844, -1.546) over 2 years than patients without co-morbidities, after adjusting for possible confounders including disease activity and randomized treatment. Patients with co-morbidities had over time lower chances of achieving remission (OR = 0.724; 95% CI: 0.604, 0.867) and a higher risk of hospitalization (OR = 3.725; 95% CI: 2.136, 6.494). CONCLUSION: At disease onset, almost half of RA patients had at least one clinically important co-morbidity. Having co-morbidities was associated with worse functionality and disease activity outcomes over 2 years, despite intensive remission induction treatment. TRIAL REGISTRATION: Clinical trials NCT01172639.

The ideal mHealth-application for rheumatoid arthritis: qualitative findings from stakeholder focus groups.

BACKGROUND: Shifts in treatment strategies for rheumatoid arthritis (RA) have made ambulatory care more labour-intensive. These developments have prompted innovative care models, including mobile health (mHealth) applications. This study aimed to explore the perceptions of mHealth-inexperienced stakeholders concerning these applications in RA care. METHODS: We performed a qualitative study by focus group interviews of stakeholders including RA patients, nurses specialised in RA care and rheumatologists. The qualitative analysis guide of Leuven (QUAGOL), which is based on grounded theory principles, was used to thematically analyse the data. In addition, the Persuasive Systems Design (PSD) model was used to structure recommended app-features. RESULTS: In total, 2 focus groups with nurses (total n = 16), 2 with patients (n = 17) and 2 with rheumatologists (n = 25) took place. Six overarching themes emerged from the analysis. Efficiency of care and enabling patient empowerment were the two themes considered as expected benefits of mHealth-use in practice by the stakeholders. In contrast, 4 themes emerged as possible barriers of mHealth-use: the burden of chronic app-use, motivational aspects, target group aspects, and legal and organisational requirements. Additionally, recommendations for an ideal mHealth-app could be structured into 4 domains (Primary Task Support, Dialogue Support, Social Support and System Credibility) according to the PSD-framework. Most recommended features were related to improving ease of use (Task Support) and System Credibility. CONCLUSIONS: Although mHealth-apps were expected to improve care efficiency and stimulate patient empowerment, stakeholders were concerned that mHealth-app use could reinforce negative illness behaviour. For mHealth-apps to be successful in practice, challenges according to stakeholders were avoiding long-term poor compliance, finding the target audience and tailoring a legal and organisational framework. Finally, the ideal mHealth-application should above all be trustworthy and easy to use.

Two-year cost-effectiveness of different COBRA-like intensive remission induction schemes in early rheumatoid arthritis: a piggyback study on the pragmatic randomised controlled CareRA trial.

OBJECTIVES: To evaluate the cost-effectiveness of treat-to-target strategies among recently diagnosed patients with rheumatoid arthritis (RA) using methotrexate (MTX) and a step-down glucocorticoid (GC) scheme (COBRA Slim) compared with (1) this combination with either sulphasalazine (COBRA Classic) or leflunomide (COBRA Avant-Garde) in high-risk patients and (2) MTX without GCs (Tight-Step-Up, TSU) in low-risk patients. METHODS: The incremental cost-utility was calculated from a healthcare perspective in the intention-to-treat population (n=379) of the 2-year open-label pragmatic randomised controlled Care in early RA trial. Healthcare costs were collected prospectively through electronic trial records. Quality-adjusted life years (QALYs) were estimated using mapping algorithms for EuroQoL-5 Dimension. Multiple imputation was used to handle missing data and bootstrapping to calculate CIs. Robustness was tested with biological disease-modifying antirheumatic drugs at biosimilar prices. RESULTS: In the high-risk group, Classic (∆k€1.464, 95% CI -0.198 to 3.127) and Avant-Garde (∆k€0.636, 95% CI -0.987 to 2.258) were more expensive compared with Slim and QALYs were slightly worse for Classic (∆-0.002, 95% CI -0.086 to 0.082) and Avant-Garde (∆-0.009, 95% CI -0.102 to 0.084). This resulted in the domination of Classic and Avant-Garde by Slim. In the low-risk group, Slim was cheaper (∆k€-0.617, 95% CI -2.799 to 1.566) and QALYs were higher (∆0.141, 95% CI 0.008 to 0.274) compared with TSU, indicating Slim dominated. Results were robust against the price of biosimilars. CONCLUSIONS: The combination of MTX with a GC bridging scheme is less expensive with comparable health utility than more intensive step-down combination strategies or a conventional step-up approach 2 years after initial treatment. TRIAL REGISTRATION NUMBER: NCT01172639.

Effectiveness of different combinations of DMARDs and glucocorticoid bridging in early rheumatoid arthritis: two-year results of CareRA.

OBJECTIVES: To investigate whether MTX should be combined with an additional DMARD and bridging glucocorticoids as initial treatment for patients with early RA to induce an effective long-term response. METHODS: The Care in early RA study is a two-year investigator-initiated pragmatic multicentre randomized trial. Early RA patients, naïve to DMARDs and glucocorticoids, were stratified based on prognostic factors. High-risk patients were randomized to COBRA-Classic (n = 98): MTX, sulfasalazine, prednisone step-down from 60 mg; COBRA-Slim (n = 98): MTX, prednisone step-down from 30 mg; or COBRA-Avant-Garde (n = 93): MTX, leflunomide, prednisone step-down from 30 mg. Low-risk patients were randomized to COBRA-Slim (n = 43); or Tight Step Up (TSU) (n = 47): MTX without prednisone. Clinical/radiological outcomes at year 2, sustainability of response, safety and treatment adaptations were assessed. RESULTS: In the high-risk group 71/98 (72%) patients achieved a DAS28-CRP < 2.6 with COBRA-Slim compared with 64/98 (65%) with COBRA-Classic and 69/93 (74%) with COBRA-Avant-Garde (P = 1.00). Other clinical/radiological outcomes and sustainability of response were similar. COBRA-Slim treatment resulted in less therapy-related adverse events compared with COBRA-Classic (P = 0.02) or COBRA-Avant-Garde (P = 0.005). In the low-risk group, 29/43 (67%) patients on COBRA-Slim and 34/47 (72%) on TSU achieved a DAS28-CRP < 2.6 (P = 1.00). On COBRA-Slim, low-risk patients had lower longitudinal DAS28-CRP scores over 2 years, a lower need for glucocorticoid injections and a comparable safety profile compared with TSU. CONCLUSION: All regimens combining DMARDs with glucocorticoids were effective for patients with early RA up to 2 years. The COBRA-Slim regimen, MTX monotherapy with glucocorticoid bridging, provided the best balance between efficacy and safety, irrespective of patients' prognosis. TRIAL REGISTRATION: ClinicalTrials.gov, http://www.clinicaltrials.gov, NCT01172639.

Area and individual level analyses of demographic and socio-economic disparities in COVID-19 vaccination uptake in Belgium.

Vaccination has played a major role in overcoming the COVID-19 pandemic. However, vaccination status can be influenced by demographic and socio-economic factors at individual and area level. In the context of the LINK-VACC project, the Belgian vaccine register for the COVID-19 vaccination campaign was linked at individual level with other registers, notably the COVID-19 laboratory test results and demographic and socio-economic variables from the DEMOBEL database. The present article aims at investigating to which extent COVID-19 vaccination status is associated with area level and/or individual level demographic and socio-economic factors. From a sample of all individuals tested for SARS-CoV-2 (LINK-VACC sample) demographic and socio-economic indicators are derived and their impact on vaccination coverages at an aggregated geographical level (municipality) is quantified. The same indicators are calculated for the full Belgian population, allowing to assess the representativeness of the LINK-VACC sample with respect to the impact of demographic and socio-economic disparities on vaccination uptake. In a second step, hierarchical models are fitted to the individual level LINK-VACC data to disentangle the individual and municipality effects allowing to evaluate the added value of the availability of individual level data in this context. The most important effects observed at the individual level are reflected in the aggregated data at the municipality level. Multilevel analyses show that most of the demographic and socio-economic impacts on vaccination are captured at the individual level, although accounting for area level in individual level analyses improve the overall description.

Estimated number of lives directly saved by COVID-19 vaccination programmes in the WHO European Region from December, 2020, to March, 2023: a retrospective surveillance study.

BACKGROUND: By March, 2023, 54 countries, areas, and territories (hereafter CAT) in the WHO European Region had reported more than 2·2 million COVID-19-related deaths to the WHO Regional Office for Europe. Here, we estimated how many lives were directly saved by vaccinating adults in the WHO European Region from December, 2020, to March, 2023. METHODS: In this retrospective surveillance study, we estimated the number of lives directly saved by age group, vaccine dose, and circulating variant-of-concern (VOC) period, regionally and nationally, using weekly data on COVID-19 mortality and infection, COVID-19 vaccination uptake, and SARS-CoV-2 virus characterisations by lineage downloaded from The European Surveillance System on June 11, 2023, as well as vaccine effectiveness data from the literature. We included data for six age groups (25-49 years, 50-59 years, ≥60 years, 60-69 years, 70-79 years, and ≥80 years). To be included in the analysis, CAT needed to have reported both COVID-19 vaccination and mortality data for at least one of the four older age groups. Only CAT that reported weekly data for both COVID-19 vaccination and mortality by age group for 90% of study weeks or more in the full study period were included. We calculated the percentage reduction in the number of expected and reported deaths. FINDINGS: Between December, 2020, and March, 2023, in 34 of 54 CAT included in the analysis, COVID-19 vaccines reduced deaths by 59% overall (CAT range 17-82%), representing approximately 1·6 million lives saved (range 1·5-1·7 million) in those aged 25 years or older: 96% of lives saved were aged 60 years or older and 52% were aged 80 years or older; first boosters saved 51% of lives, and 60% were saved during the Omicron period. INTERPRETATION: Over nearly 2·5 years, most lives saved by COVID-19 vaccination were in older adults by first booster dose and during the Omicron period, reinforcing the importance of up-to-date vaccination among the most at-risk individuals. Further modelling work should evaluate indirect effects of vaccination and public health and social measures. FUNDING: US Centers for Disease Control and Prevention.

Validation and predictive capacity of a Dutch version of the FLARE-RA questionnaire within the context of a TNFi-tapering trial.

Flare Assessment in Rheumatoid Arthritis (FLARE-RA) is a self-administered tool aiming to capture current or recent flares in rheumatoid arthritis (RA). We aimed to externally validate the FLARE-RA instrument and its existing cutoffs for flare detection within a bDMARD-tapering context in established RA. Data were analyzed from the Tapering Etanercept in Rheumatoid Arthritis (TapERA) trial, which studied the feasibility of tapering etanercept in patients with established RA in sustained remission. The English FLARE-RA was translated and cross-culturally adapted into Dutch, and internal consistency and test-retest reliability were evaluated with Crohnbach's alpha and intraclass correlation coefficient (ICC). Participants completed the FLARE-RA 3-monthly for 12 months. Accuracy and optimal cutoffs of FLARE-RA to detect DAS28-defined flares were assessed using area under the receiver operating characteristic curves (AUC). Association of FLARE-RA scores with current and future flares was studied using logistic generalized estimating equations (GEE). The Dutch FLARE-RA showed excellent internal consistency and test-retest reliability (Cronbach's alpha 0.96; ICC 0.96 [95% CI 0.70-1.00]). Discriminatory capacity of FLARE-RA to detect flares was acceptable (AUC 0.77, 0.80, and 0.72 for global, arthritis, and general symptoms subscales, respectively), with an optimal global score cutoff of 4/10. In GEE-models, higher FLARE-RA scores were associated with increased odds of both current and future flares. We successfully translated and cross-culturally adapted the FLARE-RA into a Dutch version and validated its capacity to detect flares in a bDMARD-tapering context in established RA. Finally, higher FLARE-RA scores might indicate an increased risk of future flares.Trial registration: EU Clinical Trials Register, https://www.clinicaltrialsregister.eu/ctr-search/trial/2012-004631-22/BE , EudraCT number 2012-004,631-22. Key Points • Translation and cross-cultural adaptation of the FLARE-RA resulted in a Dutch version with excellent internal consistency and test-retest reliability. • The FLARE-RA is a valid instrument to detect current OMERACT-defined flares within a bDMARD tapering setting, with an optimal global score cutoff of 4/10. • Higher scores on the FLARE-RA are associated with increased risk of future flares, which could be particularly relevant when considering DMARD tapering.

Factors underlying COVID-19 booster vaccine uptake among adults in Belgium.

OBJECTIVE: This study aimed to investigate factors influencing the uptake of first and second COVID-19 booster vaccines among adults in Belgium, particularly age, sex, region of residence and laboratory confirmed COVID-19 infection history. RESULTS: A binomial regression model was used with having received the first or second booster as outcome and age, sex, region of residence and infection history as fixed variables. Among adults, there was generally a higher uptake to receive the first booster among older age groups compared to younger ones. Females, individuals residing in Flanders and those with no previous COVID-19 infection were more likely to receive the first booster. For the second booster, the same age trend was seen as for the first booster. Males, individuals residing in Flanders and those who tested positive for COVID-19 once after first booster were more likely to receive the second booster. Individuals with multiple positive COVID-19 tests before and after primary course or first booster were less likely to receive the subsequent booster dose compared to COVID-naïve individuals. This information could be used to guide future vaccination campaigns during a pandemic and can provide valuable insights into booster uptake patterns.

Vaccine effectiveness against transmission of alpha, delta and omicron SARS-COV-2-infection, Belgian contact tracing, 2021-2022.

OBJECTIVES: Vaccine effectiveness against transmission (VET) of SARS-CoV-2-infection can be estimated from secondary attack rates observed during contact tracing. We estimated VET, the vaccine-effect on infectiousness of the index case and susceptibility of the high-risk exposure contact (HREC). METHODS: We fitted RT-PCR-test results from HREC to immunity status (vaccine schedule, prior infection, time since last immunity-conferring event), age, sex, calendar week of sampling, household, background positivity rate and dominant VOC using a multilevel Bayesian regression-model. We included Belgian data collected between January 2021 and January 2022. RESULTS: For primary BNT162b2-vaccination we estimated initial VET at 96% (95%CI 95-97) against Alpha, 87% (95%CI 84-88) against Delta and 31% (95%CI 25-37) against Omicron. Initial VET of booster-vaccination (mRNA primary and booster-vaccination) was 87% (95%CI 86-89) against Delta and 68% (95%CI 65-70) against Omicron. The VET-estimate against Delta and Omicron decreased to 71% (95%CI 64-78) and 55% (95%CI 46-62) respectively, 150-200 days after booster-vaccination. Hybrid immunity, defined as vaccination and documented prior infection, was associated with durable and higher or comparable (by number of antigen exposures) protection against transmission. CONCLUSIONS: While we observed VOC-specific immune-escape, especially by Omicron, and waning over time since immunization, vaccination remained associated with a reduced risk of SARS-CoV-2-transmission.

Sociodemographic and socioeconomic disparities in COVID-19 vaccine uptake in Belgium: a nationwide record linkage study.

BACKGROUND: Recent studies have identified important social inequalities in SARS-CoV-2 infections and related COVID-19 outcomes in the Belgian population. The aim of our study was to investigate the sociodemographic and socioeconomic characteristics associated with the uptake of COVID-19 vaccine in Belgium. METHODS: We conducted a cross-sectional analysis of the uptake of a first COVID-19 vaccine dose among 5 342 110 adults (≥18 years) in Belgium on 31 August 2021. We integrated data from four national data sources: the Belgian vaccine register (vaccination status), COVID-19 Healthdata (laboratory test results), DEMOBEL (sociodemographic/socioeconomic data) and the Common Base Register for HealthCare Actors (individuals licensed to practice a healthcare profession in Belgium). We used multivariable logistic regression analysis for identifying characteristics associated with not having obtained a first COVID-19 vaccine dose in Belgium and for each of its three regions (Flanders, Brussels and Wallonia). RESULTS: During the study period, 10% (536 716/5 342 110) of the Belgian adult population included in our study sample was not vaccinated with a first COVID-19 vaccine dose. A lower COVID-19 vaccine uptake was found among young individuals, men, migrants, single parents, one-person households and disadvantaged socioeconomic groups (with lower levels of income and education, unemployed). Overall, the sociodemographic and socioeconomic disparities were comparable for all regions. CONCLUSIONS: The identification of sociodemographic and socioeconomic disparities in COVID-19 vaccination uptake is critical to develop strategies guaranteeing a more equitable vaccination coverage of the Belgian adult population.

Clinical Severity of SARS-CoV-2 Omicron Variant Compared with Delta among Hospitalized COVID-19 Patients in Belgium during Autumn and Winter Season 2021-2022.

This retrospective multi-center matched cohort study assessed the risk for severe COVID-19 (combination of severity indicators), intensive care unit (ICU) admission, and in-hospital mortality in hospitalized patients when infected with the Omicron variant compared to when infected with the Delta variant. The study is based on a causal framework using individually-linked data from national COVID-19 registries. The study population consisted of 954 COVID-19 patients (of which, 445 were infected with Omicron) above 18 years old admitted to a Belgian hospital during the autumn and winter season 2021-2022, and with available viral genomic data. Patients were matched based on the hospital, whereas other possible confounders (demographics, comorbidities, vaccination status, socio-economic status, and ICU occupancy) were adjusted for by using a multivariable logistic regression analysis. The estimated standardized risk for severe COVID-19 and ICU admission in hospitalized patients was significantly lower (RR = 0.63; 95% CI (0.30; 0.97) and RR = 0.56; 95% CI (0.14; 0.99), respectively) when infected with the Omicron variant, whereas in-hospital mortality was not significantly different according to the SARS-CoV-2 variant (RR = 0.78, 95% CI (0.28-1.29)). This study demonstrates the added value of integrated genomic and clinical surveillance to recognize the multifactorial nature of COVID-19 pathogenesis.

Incidence and Risk Factors of COVID-19 Vaccine Breakthrough Infections: A Prospective Cohort Study in Belgium.

The objective of this study was to investigate the incidence and risk factors associated with COVID-19 vaccine breakthrough infections. We included all persons ≥18 years that had been fully vaccinated against COVID-19 for ≥14 days, between 1 February 2021 and 5 December 2021, in Belgium. The incidence of breakthrough infections (laboratory confirmed SARS-CoV-2-infections) was determined. Factors associated with breakthrough infections were analyzed using COX proportional hazard models. Among 8,062,600 fully vaccinated adults, we identified 373,070 breakthrough infections with an incidence of 11.2 (95%CI 11.2-11.3)/100 person years. Vaccination with Ad26.COV2.S (HR1.54, 95%CI 1.52-1.56) or ChAdOx1 (HR1.68, 95%CI 1.66-1.69) was associated with a higher risk of a breakthrough infection compared to BNT162b2, while mRNA-1273 was associated with a lower risk (HR0.68, 95%CI 0.67-0.69). A prior COVID-19-infection was protective against a breakthrough infection (HR0.23, 95%CI 0.23-0.24), as was an mRNA booster (HR0.44, 95%CI 0.43-0.45). During a breakthrough infection, those who had a prior COVID-19 infection were less likely to have COVID-19 symptoms of almost all types than naïve persons. We identified risk factors associated with breakthrough infections, such as vaccination with adenoviral-vector vaccines, which could help inform future decisions on booster vaccination strategies. A prior COVID-19 infection lowered the risk of breakthrough infections and of having symptoms, highlighting the protective effect of hybrid immunity.

Vaccine effectiveness against onward transmission of SARS-CoV2-infection by variant of concern and time since vaccination, Belgian contact tracing, 2021.

BACKGROUND: During the first half of 2021, we observed high vaccine effectiveness (VE) against SARS-CoV2-infection. The replacement of the alpha-'variant of concern' (VOC) by the delta-VOC and uncertainty about the time course of immunity called for a re-assessment. METHODS: We estimated VE against transmission of infection (VET) from Belgian contact tracing data for high-risk exposure contacts between 26/01/2021 and 14/12/2021 by susceptibility (VEs) and infectiousness of breakthrough cases (VEi) for a complete schedule of Ad26.COV2.S, ChAdOx1, BNT162b2, mRNA-1273 as well as infection-acquired and hybrid immunity. We used a multilevel Bayesian model and adjusted for personal characteristics (age, sex, household), background exposure, calendar week, VOC and time since immunity conferring-event. FINDINGS: VET-estimates were higher for mRNA-vaccines, over 90%, compared to viral vector vaccines: 66% and 80% for Ad26COV2.S and ChAdOx1 respectively (Alpha, 0-50 days after vaccination). Delta was associated with a 40% increase in odds of transmission and a decrease of VEs (72-64%) and especially of VEi (71-46% for BNT162b2). Infection-acquired and hybrid immunity were less affected by Delta. Waning further reduced VET-estimates: from 81% to 63% for BNT162b2 (Delta, 150-200 days after vaccination). We observed lower initial VEi in the age group 65-84 years (32% vs 46% in the age group 45-64 years for BNT162b2) and faster waning. Hybrid immunity waned slower than vaccine-induced immunity. INTERPRETATION: VEi and VEs-estimates, while remaining significant, were reduced by Delta and waned over time. We observed faster waning in the oldest age group. We should seek to improve vaccine-induced protection in older persons and those vaccinated with viral-vector vaccines.