COVID-19 vaccination uptake in Belgium: socioeconomic and sociodemographic disparities

Background

Recent studies have identified important social inequalities in SARS-CoV-2 infection and related COVID-19 outcomes in the Belgian population. This study aims to investigate socioeconomic and -demographic characteristics associated with the uptake of COVID-19 vaccine in Belgium.

Methods

We conducted a retrospective analysis of the uptake of the first dose of COVID-19 vaccine among 5,341,584 adults (≥ 18 years) tested for COVID-19 in Belgium until August 31, 2021. We integrated four national data sources: the Belgian vaccine registry (vaccination status), COVID-19 Healthdata (laboratory test results), STATBEL (socioeconomic/-demographic data) and the Common Base Registry for HealthCare Actors (people licensed to practice a healthcare profession in Belgium). Unvaccinated and vaccinated people (with at least one dose) were compared using multivariate logistic regression analysis.

Results

During the study period, 53,887 people (10%) did not receive the first COVID-19 vaccine dose in Belgium. Migrant background was associated with vaccine uptake (e.g., non-Europeans were almost three times [2.96-3.00] more likely to be unvaccinated compared to Belgian nationals). Single parents (OR 1.27 [1.26-1.28]) and people living alone (OR 1.18 [1.17-1.19]) were more likely to be unvaccinated compared to couples with children. Having a low or moderate education level (OR 1.36 [1.35-1.38] for low; OR 1.30 [1.29-1.32] for moderate) and income (OR 2.36 [2.34-2.38] for low; OR 1.54 [1.52-1.55] for moderate), being unemployed, (OR 1.50 [1.49-1.51), and having low health literacy (OR 1.41 [1.39-1.43]) led to a greater likelihood of being unvaccinated.

Conclusions

Migrants, people living alone, single parents or socioeconomically disadvantaged groups have lower uptake of COVID-19 vaccine in Belgium. The identification of these socioeconomic and -demographic disparities is critical to develop strategies guaranteeing a more equitable COVID-19 vaccination coverage in Belgium.

Key messages

• The study highlight important determinants in the uptake of the first dose of COVID-19 vaccine in Belgium.

• These results highlight the importance to focus efforts on socioeconomically disadvantaged groups currently under-represented in COVID-19 vaccination uptake in Belgium.

Un cadre conceptuel pour étudier la relation de causalité entre des variants du SARS-CoV-2 et la sévérité de la COVID-19 chez les patients hospitalisés

Contexte

Les souches de SARS-CoV-2 évoluent continuellement en accumulant des mutations dans leur génome au cours de la pandémie. Nous présentons ici un cadre conceptuel général qui permet d'étudier l'effet des variants du SARS-CoV-2 sur la sévérité de la maladie COVID-19.

Méthodes

Nous utilisons un graphe acyclique orienté (« Directed Acyclic Graph » ou DAG) pour énoncer explicitement les hypothèses sous-jacentes qui sont faites pour estimer l'effet causal de l'infection par un variant du SARS-CoV-2 sur la sévérité de la maladie COVID-19 chez des patients hospitalisés. Les DAGs sont aussi utilisés pour explorer les différents designs d’étude avec leur risque de biais de sélection. Ensuite, l'infrastructure de données spécifiques à la surveillance du COVID-19 en Belgique est décrite, avec ses forces et ses faiblesses pour étudier l'impact clinique des variants.

Résultats

Un modèle causal est défini et visualisé à l'aide d'un DAG, sur lequel figurent les variables aléatoires mesurées et d'autres non mesurées. Différentes méthodes, dont un design de cohortes appariées, sont proposées pour fixer les associations non causales. Les biais de sélection potentiels, notamment dans la sélection des patients pour un séquençage du génome complet (WGS) en se basant sur la charge virale ou la sévérité de l'infection, sont mis en évidence. Les limites de l'infrastructure de données actuelle, y compris l'enregistrement non exhaustif des patients hospitalisés pour COVID-19, sont décrites.

Discussion/Conclusion

Un cadre bien établi qui fournit une vue complète de la sévérité de la maladie COVID-19 en combinant des informations provenant de différentes sources, permettra d'évaluer l'impact clinique des variants émergents. Le cadre montre la complexité liée à la recherche causale, les données nécessaires correspondantes et il souligne des limitations importantes comme des facteurs de confusion non mesurés ou un biais de sélection, inhérentes à la réorientation des registres de données COVID-19 de routine existants.

Déclaration de liens d'intérêts

Les auteurs déclarent ne pas avoir de liens d'intérêts.

Dopaminergic modulation of synaptic plasticity in rat prefrontal neurons

The prefrontal cortex (PFC) is thought to store the traces for a type of long-term memory - the abstract memory that determines the temporal structure of behavior often termed a "rule" or "strategy". Long-term synaptic plasticity might serve as an underlying cellular mechanism for this type of memory. We therefore studied the induction of synaptic plasticity in rat PFC neurons, maintained in vitro, with special emphasis on the functionally important neuromodulator dopamine. First, the induction of long-term potentiation (LTP) was facilitated in the presence of tonic/background dopamine in the bath, and the dose-dependency of this background dopamine followed an "inverted-U" function, where too high or too low dopamine levels could not facilitate LTP. Second, the induction of long-term depression (LTD) by low-frequency stimuli appeared to be independent of background dopamine, but required endogenous, phasically-released dopamine during the stimuli. Blockade of dopamine receptors during the stimuli and exaggeration of the effect of this endogenously-released dopamine by inhibition of dopamine transporter activity both blocked LTD. Thus, LTD induction also followed an inverted-U function in its dopamine-dependency. We conclude that PFC synaptic plasticity is powerfully modulated by dopamine through inverted-U-shaped dose-dependency.

The effect of non-competitive NMDA receptor antagonist MK-801 on neuronal activity in rodent prefrontal cortex: an animal model for cognitive symptoms of schizophrenia

Schizophrenia affects about 1% of the world population and is a major socio-economical problem in ours societies. Cognitive symptoms are particularly resistant to current treatments and are believed to be closely related to an altered function of prefrontal cortex (PFC). Particularly, abnormalities in the plasticity processes in the PFC are a candidate mechanism underlying cognitive symptoms, and the recent evidences in patients are in line with this hypothesis. Animal pharmacological models of cognitive symptoms, notably with non-competitive NMDA receptor antagonists such as MK-801, are commonly used to investigate the underlying cellular and molecular mechanisms of schizophrenia. However, it is still unknown whether in these animal models, impairments in plasticity of PFC neurons are present. In this article, we briefly summarize the current knowledge on the effect of non-competitive NMDA receptor antagonist MK-801 on medial PFC (mPFC) neuronal activity and then introduce a form of plasticity found after acute exposure to MK-801, which was accompanied by cognitive deficits. These observations suggest a potential correlation between cognitive deficits and the aberrant plasticity in the mPFC in the animal model of schizophrenia.

Inhibition of dopamine transporter activity impairs synaptic depression in rat prefrontal cortex through over-stimulation of D1 receptors

In rat prefrontal cortex (PFC), long-term depression induced by low-frequency single stimuli has never been studied. Combined with the well-documented involvement of dopamine transporters (DATs) in the regulation of PFC-dependent cognitive processes, it is important to test whether this form of plasticity can be modulated by DAT activity in the PFC. Here, we show first that prolonged 3-Hz stimuli successfully induced synaptic depression in rat PFC slices whose induction depended on endogenous stimulation of D1-like and D2-like receptors and the activation of extracellular signal-regulated kinase 1/2 (ERK1/2). This depression was found to be significantly impaired by selective inhibition of the DAT by GBR12909 (1-200 nM) or GBR12935 (100 nM). The excess amount of extracellular dopamine caused by DAT inhibition acted critically on D1-like receptors to impair depression. Furthermore, this impairment by GBR12 909 was cancelled by the allosteric-positive mGluR5 modulator CDPPB, the drug known to reverse hyperdopaminergia-induced abnormal PFC activity, and the associated cognitive disturbances. Finally, these induction, impairment, and restoration of synaptic depression were correlated by an inverted-U shape manner with the phosphorylation level of ERK1/2. We suggest that abnormal increases of the extracellular dopamine level by DAT inhibition impair synaptic depression in the PFC through over-stimulation of D1-like receptors.

Sensory and affective judgments of skin during inter- and intrapersonal touch

Here we report two experiments that investigated the tactile perception of one's own skin (intrapersonal touch) versus the skin of other individuals (interpersonal touch). In the first experiment, thirteen female participants rated, along four perceptual attributes, the skin of their own palm and volar forearm, then that of several of the other participants. Ratings were made using visual analogue scales for perceived smoothness, softness, stickiness, and pleasantness. One's own skin was rated less pleasant than the skin of others. For both intra- and interpersonal touch, the forearm skin was rated smoother, softer, less sticky and more pleasant than the palmar skin. In the second experiment, ten pairs of female participants rated each other's palm and volar forearm skin, with the skin of the touched individual being assessed before and after the application of skin emollients that alter skin feel. As in the first experiment, the untreated skin of others was rated more pleasant than the participants' own skin, and the forearm versus palm differences were replicated. However, the emollient had generally larger effects on self-assessments than the assessments of others, and the site effect showed greater positive sensory and pleasantness increases for palm versus volar forearm. The disparate results of the two experiments suggest that attention, influenced by the ecological importance of the stimulus, is more important to assessment of touched skin than ownership of the skin or the contribution to self-touch made by the additional receptors in the passively touched skin. In both experiments, the pleasantness of touched skin was associated with the skin's perceived smoothness and softness, with weak trends toward negative associations with its perceived stickiness, consistent with prior research using inanimate surfaces (e.g., textiles and sandpapers).

Prevalence and risk factors for colonisation with gram-negative bacteria in an intensive care unit

OBJECTIVE

To investigate prevalence and determine risk factors for colonisation with Gram-negative bacteria in ICU patients.

DESIGN

Prospective, surveillance study.

SETTING

26-bed surgical and paediatric ICU.

PATIENTS

159 patients--whereof 22 infants--admitted to the surgical/paediatric ICU over a two-month period.

INTERVENTION

In all patients routine microbiological monitoring was performed by thrice weekly oral swabs, urine sampling and, additionally, tracheal aspirates in patients on mechanical ventilation (MV) and by anal swabs once weekly.

RESULTS

Population characteristics: Mean age of the adult population was 51.1 +/- 17.6 year. Mean age of the paediatric population was 6.3 +/- 5.3 year. The mean APACHE II-score was 18 +/- 9.1. The mean PRISM-score was 9.7 +/- 5.4. The mean ICU stay was 7.5 +/- 11.4 days. 43.4 percent of patients received mechanical ventilation (MV). The mean number of mechanical ventilation days was 11.1 +/- 14.7 days. 32.1% of patients experienced colonisation with Gram-negative bacteria. Prevalence of colonisation increased with length of ICU stay. The probability of colonisation was 24% after an ICU stay of 3 days (= median ICU stay). Time to colonisation was not different between the controlled sites (p > 0.05). 47% of colonizations were due to multiresistant strains. Higher APACHE II-scores and MV were associated with a higher prevalence of colonisation (p < 0.01). The ICU mortality was 8% among adult and 4% among paediatric patients.

CONCLUSION

Patients with high APACHE II-scores, on mechanical ventilation and with an ICU stay of more than 3 days are most at risk for colonisation with Gram-negative bacteria. These patients should be cared with the optimal precautions in the prevention of colonisation and infection.

Kabisa: an interactive computer-assisted training program for tropical diseases

In Europe, tropical pathology is usually taught in special short courses, intended for those planning to practise in developing countries. The theoretical knowledge to be assimilated during this short period is considerable, and turning such newly acquired knowledge into competence is difficult. Kabisa is a computer-based training program for tropical diseases. Instead of concentrating on strictly tropical diseases, students are trained in recognizing diseases in patients presenting randomly in an imaginary reference hospital in a developing country. Databases are compiled by experts from experiences in various parts of Africa, Asia and tropical America. Seven languages and three levels of competence can be chosen by the student. Updating of all databases is possible by teachers who want to describe a particular setting. A 'consistency checker' verifies the internal consistency of a new configuration. The logical engine is based upon both a 'cluster' and a Bayesian logic, with built-in corrections for related disease characteristics. This correction allows calculated probabilities to stay closer to real probabilities, and avoids the 'probability overshoot' that is inherent to 'idiot Bayes' calculations. The program provides training in diagnostic skills in an imaginary second-line setting in a tropical country. It puts tropical and cosmopolitan diseases in perspective and combines applied clinical epidemiology and pattern recognition within varying sets of presenting symptoms. Students are guided in searching for the most relevant disease characteristics, in ranking disease probability, and in deciding when to stop investigating.

Azithromycin compared with clarithromycin in the treatment of adult patients with acute purulent tracheobronchitis: a cost of illness study

Adult, professionally active patients with acute purulent tracheobronchitis were treated with azithromycin (3 or 5 days; n = 62) or clarithromycin (7 to 10 days; n = 69) in an open, randomized study. Bronchitis-related costs and treatment efficacy were assessed at day 5-6 and day 14-21. Both antibiotics were of equal clinical efficacy, although the median time to improvement of symptoms was significantly shorter for azithromycin patients than for clarithromycin patients. Some 77% of azithromycin patients and 78% of clarithromycin patients were unable to work for at least 1 day. The total time when patients were unable to work was shorter for azithromycin patients than for clarithromycin patients, but this difference did not remain significant when weekends and holidays were taken into account. Further studies are needed to assess the impact of azithromycin on time to clinical improvement, on lost working days, and on the associated costs.

Bordetella pertussis as a cause of chronic respiratory infection in an AIDS patient

A 60-year-old heterosexual man with AIDS was admitted to hospital with dyspnea, a severe paroxysmal non-productive cough of two months' duration, low-grade fever and exhaustion. Bordetella pertussis was cultured from a bronchoalveolar lavage specimen. After erythromycin therapy (500 mg q.i.d. for two weeks) all respiratory symptoms resolved progressively over a four-week period. Bordetella pertussis should be added to the long list of pathogens that may cause respiratory disease in persons with HIV infection.

Imported relapsing fever in European tourists

Two 'imported' cases of relapsing fever after a trip through Senegal are described. Two women developed a tick-borne relapsing fever after having slept outdoors on a terrace in Zinguichor, Senegal. The first patient was rapidly cured after a course of doxycycline. The second patient initially received erythromycin, but despite this treatment she developed neurological symptoms and Borrelia persisted in the thick-smear examination. After treatment with doxycycline she developed a Jarish-Herxheimer reaction. Treatment with doxycycline was continued and finally all symptoms disappeared within 36 hours after starting this treatment. A diagnosis of relapsing fever should be considered in all patients returning from the tropics with recurrent fever, especially if no malaria parasites are found.

The prevalence of hairy leukoplakia in HIV seropositive and HIV seronegative immunocompromised patients

The prevalence of hairy leukoplakia was determined among 176 symptomatic HIV seropositive patients seen at the outpatient department of the Institute of Tropical Medicine in Antwerp, Belgium. Moreover, systematic tongue biopsies were performed during postmortem examination of 21 patients with AIDS, 100 HIV seronegative immunocompromised patients with haematologic or other malignancies and 100 HIV seronegative non-immunocompromised patients who died at the University Hospital Antwerp. Hairy leukoplakia was observed in 52 (29.5%) of the outpatients, but only in one (5%) of the AIDS patients in the postmortem study (P = 0.03). An explanation for this difference may be that significantly more AIDS patients who died had received either acyclovir or ganciclovir during the 3 months prior to the postmortem examination than the HIV seropositive outpatients during the 3 months prior to examination. Hairy leukoplakia occurred more often in Caucasian homosexual men with HIV infection (38%) than among heterosexual Africans with HIV infection (17%) (P = 0.06). Hairy leukoplakia was observed in none of the HIV seronegative patients.