Comparison of Dried Blood Spots and Venous Blood for the Detection of SARS-CoV-2 Antibodies in a Population of Nursing Home Residents.

In the current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, testing for SARS-CoV-2-specific antibodies is paramount for monitoring immune responses in postauthorization vaccination and seroepidemiological studies. However, large-scale and iterative serological testing by venipuncture in older persons can be challenging. Capillary blood sampling using a finger prick and collection on protein saver cards, i.e., dried blood spots (DBSs), has already proven to be a promising alternative. However, elderly persons have reduced cutaneous microvasculature, which may affect DBS-based antibody testing. Therefore, we aimed to evaluate the performance of DBS tests for the detection of SARS-CoV-2 antibodies among nursing homes residents. We collected paired venous blood and DBS samples on two types of protein saver cards (Whatman and EUROIMMUN) from nursing home residents, as well as from staff members as a reference population. Venous blood samples were analyzed for the presence of SARS-CoV-2 IgG antibodies using the Abbott chemiluminescent microparticle immunoassay (CMIA). DBS samples were analyzed by the EUROIMMUN enzyme-linked immunosorbent assay (ELISA) for SARS-CoV-2 IgG antibodies. We performed a statistical assessment to optimize the ELISA cutoff value for the DBS testing using Youden's J index. A total of 273 paired DBS-serum samples were analyzed, of which 129 were positive, as assessed by the reference test. The sensitivities and specificities of DBS testing ranged from 95.0% to 97.1% and from 97.1% to 98.8%, respectively, depending on the population (residents or staff members) and the DBS card type. Therefore, we found that DBS sampling is a valid alternative to venipuncture for the detection of SARS-CoV-2 antibodies among elderly subjects. IMPORTANCE Since the implementation of newly developed SARS-CoV-2 vaccines in the general population, serological tests are of increasing importance. Because DBS samples can be obtained with a finger prick and can be shipped and stored at room temperature, they are optimal for use in large-scale SARS-CoV-2 serosurveillance or postauthorization vaccination studies, even in an elderly study population.

Clinical burden of hepatitis E virus infection in a tertiary care center in Flanders, Belgium.

BACKGROUND: Hepatitis E virus (HEV) infection is increasingly recognized as a cause of hepatitis in developed countries. A high HEV IgG seroprevalence in humans and pigs is reported as well as sporadic clinical cases of autochtonous HEV but there are currently no data available on the clinical burden of HEV in Belgium. OBJECTIVES: The objective of the current study was to evaluate the actual clinical burden of HEV infections in our tertiary care center in Flanders, Belgium. STUDY DESIGN: In the setting of Ghent University Hospital, patients were assessed for the presence of HEV IgG and IgM as well as HEV RNA if no other cause was found for one of the following clinical presentations: a) elevation of liver enzymes in post-liver transplant; b) suspicion of acute or toxic hepatitis; c) unexplainable elevation of liver enzymes; d) cirrhosis with acute-on-chronic exacerbation. RESULTS: In a period of 39 months (January 2011-April 2014) 71 patients were enrolled. HEV IgG was found positive in 13 (18,3%) patients; HEV IgM in 6 patients (8,5%) and HEV RNA in 4 (5,6%) patients. All HEV IgM/RNA positive patients were male, aged 41-63, and classified in the clinical groups a), b) or d). HEV IgG seroprevalence was slightly higher but not significantly different from the seroprevalence in the general population in this region in Belgium previously reported to be 14% (p-value 0.41) by our group. CONCLUSIONS: HEV should be considered as a cause of liver pathology especially in middle-aged men with elevation of liver enzymes.

Hepatitis E virus serology and PCR: does the methodology matter?

Hepatitis E virus (HEV) genotype 3 is an emerging pathogen in the developed world. As the clinical manifestations and routine laboratory parameters are often nonspecific, accurate diagnostic tests are crucial. In the current study, the performance of six serological assays and three PCR assays for the detection of HEV was evaluated. In the setting of the Ghent University Hospital, patients with clinically suspected HEV infection were tested for the presence of HEV IgM and IgG as well as HEV RNA. Serology was performed using six commercial HEV ELISA assays: Biorex, Wantai and Mikrogen IgM and IgG. HEV RNA was detected using one commercial assay (Altona RealStar®), and two optimized in-house real-time RT-PCR assays (according to Jothikumar et al., 2006 and Gyarmati et al., 2007). In addition, all three PCR assays were performed on 16 external quality control (EQC) samples. In a period of 39 months (January 2011-April 2014), 70 patients were enrolled. Using different ELISA assays, the prevalence of antibodies varied from 5.7% to 14.3% for HEV IgM and from 15.7% to 20.0% for IgG. All but two of the results of the PCR assays performed on clinical samples agreed. However, 10 out of 16 EQC samples results showed major discrepancies. We observed important differences in the performance of various serological and PCR assays. For this reason, results of both serological and molecular tests for HEV should be interpreted with caution.