Large-scale IgM and IgG SARS-CoV-2 serological screening among healthcare workers with a low infection prevalence based on nasopharyngeal swab tests in an Italian university hospital: Perspectives for public health

BACKGROUND

Healthcare workers (HCWs) are highly exposed to SARS-CoV-2 infection given their specific tasks. The IgG-IgM serological assay has demonstrated good accuracy in early detection in symptomatic patients, but its role in the diagnosis of asymptomatic patients is uncertain. The aim of our study was to assess IgM and IgG prevalence in sera in a large cohort of HCWs previously subjected to Nasopharyngeal swab test (NST) after accurate risk assessment due to positive COVID-19 patient exposure during an observation period of 90 days.

METHODS

2407 asymptomatic HCWs that had close contact with COVID-19 patients in the period between April 8th and June 7th were screened with NST based on the RT-PCR method. In parallel, they underwent large-scale chemiluminescence immunoassays involving IgM-IgG serological screening to determine actual viral spread in the same cohort.

RESULTS

During the 90-day observation period, 18 workers (0.75%) resulted positive for SARS-CoV-2 infection at the NST, whereas the positivity rates for IgM and IgG were 11.51% and 2.37%, respectively (277 workers). Despite high specificity, serological tests were inadequate for detecting SARS-CoV-2 infection in patients with previous positive NST results (IgM and IgG sensitivities of 27.78% and 50.00%, respectively).

CONCLUSIONS

These findings indicate a widespread low viral load of SARS-CoV-2 among hospital workers. However, serological screening showed very low sensitivity with respect to NST in identifying infected workers, and negative IgG and IgM results should not exclude the diagnosis of COVID-19. IgG-IgM chemiluminescence immunoassays could increase the diagnosis of COVID-19 only in association with NST, and this association is considered helpful for decision-making regarding returning to work.

Serological screening for hepatitis C during pregnancy: Seroprevalence and maternal and neonatal outcomes in 45,000 pregnant women

OBJECTIVES

The study evaluates the trend over time and the results of serological screening for hepatitis C infection in pregnancy and obstetric and neonatal outcomes.

STUDY DESIGN

It is a retrospective observational study of all pregnant women delivered in maternity units in Trento province, North East Italy, between 2009-2018. Serological screening data for hepatitis C virus were collected through the birth attendance certificate that is the mandatory tool in Italy for the birth report and the monitoring of the pregnancy, childbirth and health of the newborn. We also used the informations collected in the Hospital information system in order to get, for confirmed positive cases, the data of the entire serological profile. On this basis, we calculated the coverage of serological screening, the seroprevalence of the infection and the obstetric and neonatal outcomes.

RESULTS

A total of 45,493 pregnant women were analysed, 75.5% Italians and 24.5% foreigners. The mean coverage for serological HCV screening in pregnancy was 99.4%. 177 women tested positive for HCV antibodies (107 Italian and 70 foreign women). Mean overall seroprevalence in pregnant women was 3.9‰ (95% CI: 3.8-4.0); amongst Italians it was 3.2‰ (95% CI: 3.0-3.4) and amongst foreigners it was 6.1‰ (95% CI: 5.9-6.2). The highest seroprevalence was recorded in mothers coming from Asian countries. HCV positive mothers present an excess risk for intrahepatic cholestasis and gestational diabetes compared to HCV negative mothers. The neonatal outcomes considered bring to light a statistically significant increase in preterm births, low birth weight, elective Caesarean births, hospitalisation at birth and bottle- or mixed-feeding vs breast-only feeding. There are differences in obstetric and neonatal outcomes in relation to the HCV positive subgroup of the mother defined in particular by exposure to smoke and/or opioids.

CONCLUSIONS

The availability and integration of current information sources allows you to verify compliance with national recommendations on the serological screening of hepatitis C virus infection, to determine infection seroprevalence, the characteristics of the cases and the obstetric and neonatal outcomes. Only part of the maternal and neonatal outcomes studied can be attributed to the presence of HCV.

Comparison of Epstein-Barr Virus Serological Tools for the Screening and Risk Assessment of Nasopharyngeal Carcinoma: a Large Population-based Study

Epstein-Barr virus (EBV)-based serologic antibody testing has been found to be a feasible alternative for nasopharyngeal carcinoma (NPC) screening in endemic areas. The purpose of this study was to evaluate the performance of ELISA based on VCA IgA antibody, EA-IgA and Rta-IgG antibody specific to EBV in the diagnosis of NPC. A total of 2155 untreated NPC patients and 6957 healthy volunteers without nasopharyngeal disorder were recruited, and all subjects received EBV VCA-IgA, EA-IgA and Rta-IgG antibody tests simultaneously. The diagnostic efficiency of three testing alone or in combination for the diagnosis of NPC was evaluated. The prevalence of IgA antibody against EBV-VCA, IgA antibody against EBV-EA and IgG antibody against EBV-Rta was 89.9%, 46.6% and 63.2%. The sensitivity, specificity, positive predictive value, negative predictive value and Youden index were 89.88%, 89.65%, 73.18%, 96.63% and 0.79 for the EBV VCA-IgA antibody test, 46.59%, 96.89%, 82.5%, 85.42% and 0.43 for the EA-IgA antibody test, and 63.25%, 94.87%, 79.48%, 89.29% and 0.58 for the Rta-IgG antibody test in the diagnosis of NPC, and ROC curve analysis revealed the greatest diagnostic efficiency for EBV VCA-IgA antibody test and the lowest efficiency for EBV EA-IgA antibody test in the diagnosis of NPC. In addition, the simultaneous triple positivity of VCA-IgA, EA-IgA and Rta-IgG antibodies specific to EBV indicated the highest risk of NPC, and the simultaneous triple negativity of the three types of anti-EBV antibodies suggested the lowest risk of NPC. Our data demonstrate that EBV VCA-IgA antibody test shows a higher diagnostic efficiency than EA-IgA and Rta-IgG antibody tests for the screening of NPC, and triple positivity of is a better biomarker for the diagnosis of NPC.

Serological screening of immunoglobulin M and immunoglobulin G during pregnancy for predicting congenital cytomegalovirus infection

Background

Cytomegalovirus (CMV) is one of the most frequent pathogens for congenital infections. Most cases of congenital CMV infection (cCMV) are asymptomatic at birth, but sensorineural hearing loss (SNHL) or neurodevelopmental delay can appear later in childhood. This prospective study examined the practicability of serological screening for anti-CMV immunoglobulin (Ig) G and anti-CMV IgM in pregnant women.

Methods

A total of 11,753 pregnant women were examined for CMV IgG and CMV IgM during the first or second trimester. When IgM was positive, IgG was reevaluated more than two weeks later. When IgG was negative, IgG was reevaluated in the second or third trimester. All neonates from mothers with positive/borderline IgM or IgG seroconversion underwent polymerase chain reaction assay for CMV using urine samples to diagnose cCMV. Levels of IgG and IgM were compared between mothers with and without cCMV. Receiver operating characteristic (ROC) curves for IgM titers were analyzed.

Results

Eight of 500 neonates (1.6%) born from mothers with positive IgG and positive IgM, and 3 of 13 neonates (23.1%) born from mothers with IgG seroconversion were diagnosed with cCMV. Neither IgM titers nor IgG titers differed significantly between cCMV and non-cCMV groups. The area under the ROC curve was 0.716 and the optimal cut-off for IgM was 7.28 index (sensitivity = 0.625, specificity = 0.965, positive predictive value = 0.238, negative predictive value = 0.993). Titers of IgG were not frequently elevated in pregnant women with positive IgM during the observation period, including in those with cCMV. All 11 cCMV cases were asymptomatic at birth and none had shown SNHL or developmental delay as of the last regular visit (mean age, 40 months).

Conclusions

Seroconversion of CMV IgG and high-titer IgM during early pregnancy are predictors of cCMV. High IgM titer (> 7.28 index) is a predictor despite relatively low sensitivity. Levels of IgG had already plateaued at first evaluation in mothers with cCMV. Maternal screening offered insufficient positive predictive value for diagnosing cCMV, but allowed identifying asymptomatic cCMV cases in an early stage.

Emerging Rodent-Borne Viral Zoonoses in Trento, Italy

Rodent-borne hanta- and arenaviruses are an emerging public health threat in Europe; however, their circulation in human populations is usually underestimated since most infections are asymptomatic. Compared to other European countries, Italy is considered 'low risk' for these viruses, yet in the Province of Trento, two pathogenic hantaviruses (Puumala and Dobrava-Belgrade virus) and one arenavirus (Lymphocytic Choriomeningitis Virus) are known to circulate in rodent reservoirs. In this paper, we performed a follow-up serological screening in humans to detect variation in the prevalence of these three viruses compared to previous analyses carried out in 2002. We also used a statistical model to link seropositivity to risk factors such as occupational exposure, cutting firewood, hunting, collecting mushrooms, having a garden and owning a woodshed, a dog or a companion rodent. We demonstrate a significant increase in the seroprevalence of all three target viruses between 2002 and 2015, but no risk factors that we considered were significantly correlated with this increase. We conclude that the general exposure of residents in the Alps to these viruses has probably increased during the last decade. These results provide an early warning to public health authorities, and we suggest more detailed diagnostic and clinical investigations on suspected cases.

Screening tests for hepatitis B virus, hepatitis C virus, and human immunodeficiency virus in blood donors: evaluation of two chemiluminescent immunoassay systems

Automated chemiluminescent immunoassays (CLIAs) are useful for the detection of hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus 1/2 antigen/antibodies (HIV 1/2 Ag/Ab) in blood donor screening. Eight hundred and forty serum samples were tested for hepatitis B surface antigen (HBsAg), HCV antibodies (anti-HCV), and HIV1/2 Ag/Ab in parallel using 2 different CLIAs (Abbott Architect i2000SR and Roche Cobas e411). The concordance between the 2 systems was high (Cohen's kappa 0.97 for HBsAg, 0.77 for anti-HCV, 0.92 for HIV1/2 Ag/Ab) and the specificity and the positive predictive value were comparable. Among the 12 discrepant results, 11 were false-positive and 1 (reactive by Architect) was true-positive for anti-HCV. Positivity for HBV DNA, HCV RNA, and HIV RNA was recorded in 90.9%, 38.9%, and 100% of true-positive samples, respectively. This study represents the first stringent comparison between Architect i2000SR and Cobas e411 in blood donors. We observed a good correlation and high agreement among HBV, HCV, and HIV with the 2 automated systems.