We determined and compared the humoral immune response in severe, hospitalized and mild, non-hospitalized COVID-19 patients. Severe patients (n=38) develop a robust antibody response to SARS-CoV-2, including IgG and IgA antibodies. The geometric mean 50% virus neutralization titer is 1:240. SARS-CoV-2 infected hospital personnel (n=24), who developed mild symptoms necessitating leave of absence, self-isolation, but not hospitalization, 75 % develop antibodies, but with low/absent virus neutralization (60% < 1:20). While severe COVID-19 patients develop a strong antibody response, mild SARS-CoV-2 infections induce a modest antibody response. Long term monitoring will show whether these responses predict protection against future infections.

Serology is a crucial part of the public health response to the ongoing SARS-CoV-2 pandemic. Here, we describe the development, validation and clinical evaluation of a protein micro-array as a quantitative multiplex immunoassay that can identify S and N-directed SARS-CoV-2 IgG antibodies with high specificity and sensitivity and distinguish them from all currently circulating human coronaviruses. The method specificity was 100% for SARS-CoV-2 S1 and 96% for N antigen based on extensive syndromic (n=230 cases) and population panel (n=94) testing that also confirmed the high prevalence of seasonal human coronaviruses. To assess its potential role for both SARS-CoV-2 patient diagnostics and population studies, we evaluated a large heterogeneous COVID-19 cohort (n=330) and found an overall sensitivity of 89% (≥ 21 days post onset symptoms (dps)), ranging from 86% to 96% depending on severity of disease. For a subset of these patients longitudinal samples were provided up to 56 dps. Mild cases showed absent or delayed, and lower SARS-CoV-2 antibody responses. Overall, we present the development and extensive clinical validation of a multiplex coronavirus serological assay for syndromic testing, to answer research questions regarding to antibody responses, to support SARS-CoV-2 diagnostics and to evaluate epidemiological developments efficiently and with high-throughput.

We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log 10 increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV—CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences—is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.

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We determined and compared the humoral immune response in severe, hospitalized and mild, non-hospitalized COVID-19 patients. Severe patients (n=38) develop a robust antibody response to SARS-CoV-2, including IgG and IgA antibodies. The geometric mean 50% virus neutralization titer is 1:240. SARS-CoV-2 infected hospital personnel (n=24), who developed mild symptoms necessitating leave of absence, self-isolation, but not hospitalization, 75 % develop antibodies, but with low/absent virus neutralization (60% < 1:20). While severe COVID-19 patients develop a strong antibody response, mild SARS-CoV-2 infections induce a modest antibody response. Long term monitoring will show whether these responses predict protection against future infections.

Introduction Several Public Health Services and general practitioners in the Netherlands observed an increase in scabies in the Netherlands. Since individual cases of scabies are not notifiable in the Netherlands, the epidemiological situation is mostly unknown. To investigate the scabies incidence in the Netherlands, we described the epidemiology of scabies between 2011 and 2021. Methods Two national data sources were analysed descriptively. One data source obtained incidence data of scabies (per 1,000 persons) of persons consulting in primary care from 2011–2020. The other data source captured the number of prescribed scabicides in the Netherlands from 2011–2021. To describe the correlation between the incidence of diagnoses and the number of dispensations between 2011 and 2020, we calculated a correlation coefficient. Results The incidence of reported scabies has increased by more than threefold the last decade (2011–2020), mainly affecting adolescents and (young) adults. This was also clearly reflected in the fivefold increase in dispensations of scabicide medication during 2011–2021. The incidence and dispensations were at an all-time high in 2021. We found a strong correlation between the reported incidence and the number of dispensations between 2011 and 2020. Conclusions More awareness on early diagnosis, proper treatment and treatment of close contacts is needed.

The i-4-1-Health project is a One Health project on the prevalence and spread of antimicrobial resistance in the human and veterinary domain in the Dutch-Belgian cross-border region. This paper describes the main components of the laboratory protocol that was developed to standardise the microbiological methods used for the detection of intestinal carriage of highly-resistant microorganisms.

Background The emergence of vancomycin resistant enterococci poses a major problem in healthcare settings. Here we describe a hospital-wide outbreak of vancomycin-resistant Enterococcus faecium in a general hospital in The Netherlands in the period December 2014–February 2017. Due to late detection of the outbreak, a large cohort of approximately 25,000 (discharged) patients was classified as ‘VRE suspected’. Hereupon a mitigated screening and isolation policy, as compared with the national guideline, was implemented to control the outbreak. Methods After the outbreak was identified, a screening policy consisting of a single rectal swab culture (with enrichment broth) to discontinue isolation and removing ‘VRE suspected’ label in the electronic patient files for readmitted VRE suspected patients, was implemented. In addition to the on admission screening, periodic hospital-wide point prevalence screening, measures to improve compliance with standard infection control precautions and enhanced environmental cleaning were implemented to control the outbreak. Results Between September 2014 and February 2017, 140 patients were identified to be colonised by vanA mediated vancomycin-resistant Enterococcus faecium (VREfm). Two of these patients developed bacteraemia. AFLP typing showed that the outbreak was caused by a single clone. Extensive environmental contamination was found in multiple wards. Within nine months after the detection of the outbreak no new VRE cases were detected. Conclusion We implemented a control strategy based on targeted screening and isolation in combination with implementation of general precautions and environmental cleaning. The strategy was less stringent than the Dutch national guideline for VRE control. This strategy successfully controlled the outbreak, while it was associated with a reduction in the number of isolation days and the number of cultures taken.