Hospital-Wide SARS-CoV-2 seroprevalence in health care workers in a Spanish teaching hospital

IntroductionHospital-wide SARS-CoV-2 seroprevalence is rarely explored and can identify areas of unexpected risk. We determined the seroprevalence against SARS-CoV-2 in all health care workers (HCW) at a hospital.MethodsCross-sectional study (14-27/04/2020). We determined SARS-CoV-2 IgG by ELISA in all HCW including external workers of a teaching hospital in Madrid. They were classified by professional category, working area, and risk for SARS-CoV-2 exposure.ResultsAmong 2919 HCW, 2590 (88,7%) were evaluated. The mean age was 43.8 years (SD 11.1), and 73.9% were females. Globally, 818 (31.6%) workers were IgG positive with no differences for age, sex or previous diseases. Of these, 48.5% did not report previous symptoms. Seropositivity was more frequent in high- (33.1%) and medium- (33.8%) than in low-risk areas (25.8%, p = 0.007), but not for hospitalization areas attending COVID-19 and non-COVID-19 patients (35.5 vs 38.3% p > 0.05). HWC with a previous SARS-CoV2 PCR-positive test were IgG seropositive in 90.8%. By multivariate logistic regression analysis seropositivity was significantly associated with being physicians (OR 2.37, CI95% 1.61–3.49), nurses (OR 1.67, CI95% 1.14–2.46), nurse assistants (OR 1.84, CI95% 1.24–2.73), HCW working at COVID-19 hospitalization areas (OR 1.71, CI95% 1.22–2.40), non-COVID-19 hospitalization areas (OR 1.88, CI95% 1.30–2.73), and at the Emergency Room (OR 1.51, CI95% 1.01–2.27).ConclusionsSeroprevalence uncovered a high rate of infection previously unnoticed among HCW. Patients not suspected of having COVID-19 as well as asymptomatic HCW may be a relevant source for nosocomial SARS-CoV-2 transmission.     

Self-prescribed Ivermectin use is associated with a lower rate of seroconversion in health care workers diagnosed with COVID,in a dose-dependent response

BackgroundOver-the-counter use of ivermectin amongst other drugs as SARS-CoV-2 treatment has been increasingly common, despite the lack of evidence on its clinical efficacy.ObjectiveTo evaluate the effect of ivermectin use on production of antibodies against SARS-CoV-2 in health care workers (HCW) diagnosed with COVID-19 and of Th1/Th2 cytokines by stimulated peripheral blood mononuclear cells of the same cohort (PBMCs).MethodsThis cross-sectional study evaluated seroconversion and neutralizing antibodies production in HCW at Complexo Hospitalar Universitário Professor Edgard Santos (Salvador, Brazil), diagnosed with COVID-19 from May to July, 2020, as well as in vitro production of antibody against SARS-CoV-2 and Th1/Th2 cytokines. Analyses were performed between December 2020 and February 2021. Participants were stratified according to the use of ivermectin (≤ 1 dose vs. multiple doses) for treatment of COVID-19.Results45 HCW were included (62% women). Mean age was 39 years, and disease severity was similar across groups. Neutralizing antibodies were detected less frequently in multiple doses (70%) vs. ≤ 1 dose (97%) groups, p = 0.02). PBMCs of patients in multiple doses group also were less likely to produce antibodies against SARS-CoV-2 following in vitro stimulation with purified spike protein in comparison with patients in ≤ 1 dose group (p < 0.001). PBMC´s production of Th1/Th2 cytokines levels was similar across groups. Abdominal pain (15% vs 46%, p = 0.04), diarrhea (21% vs. 55%, p = 0.05) and taste perversion (0% vs. 18%, p = 0.05) were more frequently reported by participants that used multiple doses of ivermectin.ConclusionsAlthough there was no evidence for differential disease severity upon ivermectin use for treatment of COVID-19 it was associated with more gastro-intestinal side-effects and impairment of anti-SARS-CoV2 antibodies production, in a dose dependent manner. This potentially impacts the effectiveness of immune response and the risk of reinfection and warrants additional studies for clarifying the mechanisms and consequences of such immunomodulatory effects.     

Anti-SARS-CoV-2 immunoglobulin profile in patients with celiac disease living in a high incidence area

Background and aimHow symptoms and antibodies related to SARS-CoV-2 infection develop in patients with celiac disease (CD) is unclear. We aimed to investigate the impact of SARS-CoV-2 infection in CD patients.MethodsCD patients were interviewed about the development of COVID-19 symptoms, compliance with anti-virus measures and adherence to a gluten-free diet (GFD). The presence of anti-SARS-CoV-2 IgG and IgA (anti-RBD and N proteins) was compared to that in non-CD subjects. Expression of the duodenal ACE2 receptor was investigated. When available, data on duodenal histology, anti-tissue transglutaminase IgA (tTGA), comorbidities and GFD adherence were analyzed.ResultsOf 362 CD patients, 42 (12%) reported COVID-19 symptoms and 21% of these symptomatic patients presented anti-SARS-CoV-2 Ig. Overall, 18% of CD patients showed anti-SARS-CoV-2 Ig versus 25% of controls (p = 0.18). CD patients had significantly lower levels of anti-N IgA. tTGA, duodenal atrophy, GFD adherence or other comorbidities did not influence symptoms and/or antibodies. The ACE2 receptor was detected in the non-atrophic duodenal mucosa of patients; atrophy was associated with lower expression of the ACE2 receptor.ConclusionCD patients have an anti-SARS-CoV-2 Ig profile similar to non-celiac controls, except for anti-N IgA. No risk factors were identified among CD parameters and GFD adherence.     

Anti-SARS CoV-2 IgG in COVID-19 Patients with Hematological Diseases: A Single-center,Retrospective Study in Japan

Objective Coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread globally. Although the relationship between anti-SARS-CoV-2 immunoglobulin G (IgG) antibodies and COVID-19 severity has been reported, information is lacking regarding the seropositivity of patients with particular types of diseases, including hematological diseases. Methods In this single-center, retrospective study, we compared SARS-CoV-2 IgG positivity between patients with hematological diseases and those with non-hematological diseases. Results In total, 77 adult COVID-19 patients were enrolled. Of these, 30 had hematological disorders, and 47 had non-hematological disorders. The IgG antibody against the receptor-binding domain of the spike protein was detected less frequently in patients with hematological diseases (60.0%) than in those with non-hematological diseases (91.5%; p=0.029). Rituximab use was significantly associated with seronegativity (p=0.010). Conclusion Patients with hematological diseases are less likely to develop anti-SARS-CoV-2 antibodies than those with non-hematological diseases, which may explain the poor outcomes of COVID-19 patients in this high-risk group.     

SARS-CoV-2 Incidence,signs and symptoms and main risk factors for COVID-19 infection in Health Care Workers: A hospital-wide survey in Salvador,Brazil

BackgroundBrazil is the third country most affected by Coronavirus Disease 2019 (COVID-19) in the world. Health care workers (HCWs) are at higher risk of infection. Despite the increasing numbers of studies on the topic, There are gaps in the knowledge of characteristics and risk factors for infection of HCWS. This information is important to design preventive strategies and to mitigate the disease impact. The objective of this study was to estimate the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, to identify factors associated, and to describe symptoms reported by healthcare workers at a tertiary hospital in Salvador, Brazil.MethodsAll HCWs were evaluated in a cross-sectional study conducted between May and September 2020, using self-administered questionnaires, and screening all participants for SARS-COV-2 IgG and IgM antibodies by rapid tests. Reactive IgG samples were retested by ELISA and IgM-positive test had a saliva sample retest by RT-PCR. Univariate associations were estimated by a non-adjusted incidence proportion ratio. Variables associated with COVID-19 incidence at p < 0.20 were selected for inclusion in a binary logistic regression model.ResultsA total of 2083 HCWs were included, mean age 41±10 years, 71.8% women, and 77.8% non-white. Of these, 271 (13.0%) and 25 (1.2%) HCWs tested positive for IgG and IgM SARS-CoV-2 antibodies, respectively, and three had a positive RT-PCR. Ancillary work [Odds Ratio (OR): 4.96], elementary education (OR: 2.91), high school education (OR: 2.89), and catholic religion (OR: 2.16) were associated with an increased likelihood of a positive IgG antibodies against SARS-CoV-2. Anosmia [Incidence Proportion Ratio (IPR): 7.41] and ageusia (IPR:8.51) were the most frequent associated symptoms.ConclusionHCWs with low mean family income, lower level of schooling, ancillary workor being black had a significantly higher likelihood of testing positive for SARS-CoV-2 antibodies. Social vulnerability was an important risk factor for COVID-19 infection.     

kinetics of anti-SARS-CoV-2 antibodies over time. Results of 10 month follow up in over 300 seropositive Health Care Workers

BackgroundThe kinetics of the antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) needs to be evaluated since long-term duration of antibody remains largely unknown, particularly in infected healthcare workers (HCW).MethodsProspective study, evaluating the longitudinal profile of anti-SARS-CoV-2 antibody titers in a random sample of 331 seropositive healthcare workers (HCW) of Spanish Hospitals Group. Serial measurements of serum IgG-anti-SARS-CoV-2 were obtained at baseline (April-May,2020), and in 2 follow-up visits. Linear mixed models were used to investigate antibody kinetics and associated factors.ResultsA total of 306 seropositive subjects (median age: 44.7years;69.9% female) were included in the final analysis. After a median follow-up of 274 days between baseline and final measurement, 235(76.8%) maintained seropositivity. Antibody titers decreased in 82.0%, while remained stable in 13.1%. Factors associated with stability of antibodies over time included age≥45 years, higher baseline titers, severe/moderate infection and high-grade exposure to COVID-19 patients. In declining profile, estimated mean antibody half-life was 146.3 days(95%CI:138.6–154.9) from baseline. Multivariate models show independent longer durability of antibodies in HCW with high-risk exposure to COVID-19 patients (+14.1 days;95%CI:0.6–40.2) and with symptomatic COVID-19 (+14.1 days;95%CI:0.9–43.0). The estimated mean time to loss antibodies was 375(95% CI:342–408) days from baseline.ConclusionsWe present the first study measuring the kinetics of antibody response against SARS-CoV-2 in HCW beyond 6 months. Most participants remained seropositive after 9 months but presented a significant decline in antibody-titers. Two distinct antibody dynamic profiles were observed (declining vs. stable). Independent factors associated with longer durability of antibodies were symptomatic infection and higher exposure to COVID-19 patients.     

Effectiveness of the BNT162b2 mRNA Covid-19 vaccine in Spanish healthcare workers

IntroductionFrontline health care workers (HCW) have higher risk than the general population to become infected by SARS.CoV.2, so they were a priority group for Covid-19 vaccine administration. We compared the incidence and prevalence of HCW infected pre-and post-vaccination with the BNT162b2 mRNA COVID-19 vaccine.Material and methodsProspective observational study carried out between 01/12/20 and 07/03/21 in La Paz University Hospital, Madrid (Spain). SARS.CoV.2 positive cases in HCW after vaccination were collected and compared to those hospitalized COVID-19 patients at the same hospital.ResultsTwo weeks after finishing the first round of vaccinations daily new cases of HCW infections (symptomatic and asymptomatic) decreased substantially and cumulative cases of infected HCW and hospitalized COVID-19 patients started to diverge. No new positive cases of HCW infection were registered seven days after the second dose of BNT162b2 mRNA COVID-19 vaccine.ConclusionsBNT162b2 mRNA COVID-19 vaccine is highly effective in Spanish HCW.     

Impaired anti-SARS-CoV-2 antibody response in non-severe COVID-19 patients with diabetes mellitus: A preliminary report

Background and aimsPatients with diabetes mellitus (DM) often demonstrate impaired antibody response to influenza/hepatitis B vaccines. Hence, we compared anti-SARS-CoV-2 antibody response in non-severe COVID-19 patients with and without type 2 diabetes mellitus (T2DM).MethodsRecords of non-severe COVID-19 patients admitted at our institution between April 10, 2020 and May 20, 2020 were retrieved. Qualitative detection of total (IgG + IgM) anti-SARS-CoV-2 antibody was performed using electrochemiluminescence immunoassay in plasma samples collected at least 14 days post-polymerase chain reaction (PCR) confirmation of diagnosis.ResultsThirty-one non-severe COVID-19 patients were included. Nine patients (29%) had T2DM with mean HbA_1c at admission of 8.3 ± 1.0%. Anti-SARS-CoV-2 antibody was estimated at a median of 16 (14–17) days post-PCR confirmation of COVID-19 diagnosis. Only three patients (10%) were seronegative, and all had T2DM. Patients with T2DM were more likely to have non-detectable anti-SARS-CoV-2 antibodies than those without DM (p = 0.019).ConclusionsCOVID-19 patients with T2DM may not undergo seroconversion even after two weeks of diagnosis. Impaired seroconversion could theoretically increase the risk of reinfections in patients with DM. However, the finding requires validation in large-scale studies involving serial estimations of anti-SARS-CoV-2 antibodies in patients with and without DM.     

Study on Continuation of Antibody Prevalence Six Months after Detection of Subclinical Severe Acute Respiratory Syndrome Coronavirus 2 Infections

Objective To examine the continuation of antibody prevalence and background factors in antibody-positive subjects after asymptomatic infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods A study was carried out to investigate the SARS-CoV-2 antibody (IgG) prevalence. SARS-CoV-2 antibodies (IgG) were measured and analyzed with immunochromatographic tests. Patients Among 1,603 subjects, comprising patients, physicians, and nurses at 65 medical institutes in Kanagawa, Japan, 39 antibody-positive subjects received follow-up for 6 months. Results Of the 33 subjects who consented to the follow-up (23 patients and 10 medical professionals), continued positivity of IgG antibodies was confirmed in 11 of 32 cases (34.4%) after 2 months, 8 of 33 (24.2%) after 4 months, and 8 of 33 (24.2%) after 6 months. A significant difference was found in the sleeping time, drinking habits, hypertension, and use of angiotensin-receptor blockers on comparing subject background characteristics among three groups: patients with antibody production that continued for six months after the first detection of positivity, patients in whom antibody production stopped at four months, and patients in whom antibody production stopped at two months. Conclusion The continuation rate of IgG antibody prevalence was 24.2% at 6 months after the first detection of antibody positivity in cases with asymptomatic coronavirus disease 2019 (COVID-19) infections. This percentage is low compared with the antibody continuation rate in patients who have recovered from symptomatic COVID-19 infection.     

Seroprevalencia de infección frente a SARS-CoV-2 en trabajadores de la salud en un hospital monográfico pediátrico en Madrid (España)

IntroductionAs of 30 April 2020, 203.715 SARS-CoV-2 infections had been reported in Spain, 54.486 in Madrid, 21.4% were health care workers. Our objective is to determine seroprevalence of COVID-19 among workers in a monographic pediatric hospital.MethodsBetween April13^th and 30^th, 1.523 health workers were recruited to be tested for SARS-CoV-2 serology screening (All Test®) and they answered a questionnaire with demographic, epidemiological and clinical information and previous exposure to COVID-19.FindingsOne thousand two hundred ninety two (84.8%) were tested. Positive serology (IgM and/or IgG) to SARS-CoV-2 was found in 17.2% (222/1.292), in 15.5% (201/1.292) if only IgG was considered. Median age was 44±13 years, 73% were female. The 33.8% (75/222) were asymptomatic. Eighty one had a previous positive rRT-PCR. The 14% (32/222) referred a family contact.ConclusionSerology prevalence for SARS-CoV-2 in workers of a pediatric hospital was higher than in general population. Many of them had an unnoticed infection.     

Distinct Antibody Responses to Endemic Coronaviruses Pre- and Post-SARS-CoV-2 Infection in Kenyan Infants and Mothers

Pre-existing antibodies that bind endemic human coronaviruses (eHCoVs) can cross-react with SARS-CoV-2, which is the betacoronavirus that causes COVID-19, but whether these responses influence SARS-CoV-2 infection is still under investigation and is particularly understudied in infants. In this study, we measured eHCoV and SARS-CoV-1 IgG antibody titers before and after SARS-CoV-2 seroconversion in a cohort of Kenyan women and their infants. Pre-existing eHCoV antibody binding titers were not consistently associated with SARS-CoV-2 seroconversion in infants or mothers; however, we observed a very modest association between pre-existing HCoV-229E antibody levels and a lack of SARS-CoV-2 seroconversion in the infants. After seroconversion to SARS-CoV-2, antibody binding titers to the endemic betacoronaviruses HCoV-OC43 and HCoV-HKU1, and the highly pathogenic betacoronavirus SARS-CoV-1, but not the endemic alphacoronaviruses HCoV-229E and HCoV-NL63, increased in the mothers. However, eHCoV antibody levels did not increase following SARS-CoV-2 seroconversion in the infants, suggesting the increase seen in the mothers was not simply due to cross-reactivity to naively generated SARS-CoV-2 antibodies. In contrast, the levels of antibodies that could bind SARS-CoV-1 increased after SARS-CoV-2 seroconversion in both the mothers and infants, both of whom were unlikely to have had a prior SARS-CoV-1 infection, supporting prior findings that SARS-CoV-2 responses cross-react with SARS-CoV-1. In summary, we found evidence of increased eHCoV antibody levels following SARS-CoV-2 seroconversion in the mothers but not the infants, suggesting eHCoV responses can be boosted by SARS-CoV-2 infection when a prior memory response has been established, and that pre-existing cross-reactive antibodies are not strongly associated with SARS-CoV-2 infection risk in mothers or infants.     

Factors associated with risk of COVID-19 contagion for endoscopy healthcare workers: A survey from the Italian society of digestive endoscopy

Background and aimsThe present study was aimed to assess the risk of SARS-CoV-2 infection and associated factors among HCWs in endoscopy centers in Italy.MethodsAll members of the Italian Society of Digestive Endoscopy (SIED) were invited to participate to a questionnaire-based survey during the first months of the COVID-19 outbreak in Italy.Results314/1306 (24%) SIED members accounting for 201/502 (40%) endoscopic centers completed the survey. Personal Protection Equipment (PPE) were available in most centers, but filtering face-piece masks (FFP2 or FFP3) and negative pressure room were not in 10.9 and 75.1%. Training courses on PPE use were provided in 57.2% of centers only; there was at least one positive HCW in 17.4% of centers globally, 107/3308 (3.2%) HCWs were diagnosed with COVID-19 with similar rates of physicians (2.9%), nurses (3.5%) and other health operators (3.5%). Involvement in a COVID-19 care team (OR: 4.96) and the lack of training courses for PPE, (OR: 2.65) were associated with increased risk.ConclusionsThe risk of COVID-19 among endoscopy HCWs was not negligible and was associated with work in a COVID-19 care team and lack of education on proper PPE use. These data deserve attention during the subsequent waves.     

Preservation of anti-SARS-CoV-2 neutralising antibodies in convalescent plasma after pathogen reduction with methylene blue and visible light

BackgroundCOVID-19 convalescent plasma (CCP) is an experimental treatment against SARS-CoV-2. Although there has so far been no evidence of transmission through transfusion, pathogen reduction technologies (PRT) have been applied to CCP to mitigate risk of infectious disease. This study aims to assess the impact of methylene blue (MB) plus visible light PRT on the virus-neutralising activity of the specific antibodies against SARS-CoV-2.Material and methodsThirty-five plasma doses collected by plasmapheresis from COVID-19 convalescent donors were subjected to MB plus visible light PRT. Anti-SARS-CoV-2 RBD S1 epitope IgGs antibodies were quantified by ELISA. Titres of SARS-CoV-2 neutralising antibodies (NtAbs) were measured before and after the PRT process. A Spearman’s correlation was run to determine the relationship between antibody neutralisation ability and SARS-CoV-2 IgG ELISA ratio. Pre- and post-inactivation neutralising antibody titres were evaluated using a Wilcoxon test.ResultsThe plasma pathogen reduction procedure did not diminish NtAbS titres and so did not cause a change in the viral neutralisation capacity of CCP. There was a strong correlation between pre-and post-PRT NtAbs and anti-SARS-CoV-2 IgGs titres.DiscussionOur results showed PRT with MB did not impair the CCP passive immunity preserving its potential therapeutic potency. Therefore, PRT of CCP should be recommended to mitigate the risk for transmission of transfusion-associated infectious disease. There is a good correlation between SARS-CoV-2 IgG titres determined by ELISA and the neutralising capacity. This allows blood centres to select CCP donors based on IgG ELISA titres avoiding the much more labour-intensive laboratory processes for determining neutralising antibodies.     

Symptomatic SARS-CoV-2 Reinfection in a Healthy Healthcare Worker in Italy Confirmed by Whole-Genome Sequencing

This study describes a case of SARS-CoV-2 reinfection confirmed by whole-genome sequencing in a healthy physician who had been working in a COVID-19 hospital in Italy since the beginning of the pandemic. Nasopharyngeal swabs were obtained from the patient at each presentation as part of routine surveillance. Nucleic acid amplification testing was performed on the two samples to confirm SARS-CoV-2 infection, and serological tests were used to detect SARS-CoV-2 IgG antibodies. Comparative genome analysis with whole-genome sequencing was performed on nasopharyngeal swabs collected during the two episodes of COVID-19. The first COVID-19 episode was in March 2020, and the second was in January 2021. Both SARS-CoV-2 infections presented with mild symptoms, and seroconversion for SARS-CoV-2 IgG was documented. Genomic analysis showed that the viral genome from the first infection belonged to the lineage B.1.1.74, while that from the second infection to the lineage B.1.177. Epidemiological, clinical, serological, and genomic analyses confirmed that the second episode of SARS-CoV-2 infection in the healthcare worker met the qualifications for “best evidence” for reinfection. Further studies are urgently needed to assess the frequency of such a worrisome occurrence, particularly in the light of the recent diffusion of SARS-CoV-2 variants of concern.     

Prevalence of Anti-SARS-CoV-2 Specific Antibodies in Health-Care Workers Compared to General Population during an Early Phase of the Pandemic,Tehran-Iran

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapidly transmits in general population, mainly between health-care workers (HCWs) who are in close contact with patients. Objective: To study the seropositivity of HCWs as a high-risk group compared to general population. Methods: 72 samples were obtained from HCWs working in Masih Daneshvari hospital as one of the main COVID-19 admission centers in Tehran, during April 4 to 6, 2020. Also we collected 2021 blood samples from general population. The SARS-CoV-2 specific IgM, and IgG antibodies in the collected serum specimens were measured by commercial ELISA kits. Results: Based on the clinical manifestations, 25.0%, 47.2%, and 27.8% of HCWs were categorized as symptomatic with typical symptoms, symptomatic with atypical symptoms, and asymptomatic, respectively. Symptomatic individuals with typical and atypical symptoms were 63.2% and 36.8% positive in RT-PCR test, respectively. Anti-SARS-CoV-2 IgM and IgG antibodies were detected in 15.3% and 27.8% of HCWs samples, respectively. Antibody testing in the general population indicated that SARS-CoV-2 specific IgM and IgG were found in (162/2021) 8%, and (290/2021) 14.4%, respectively. The frequency of positive cases of IgM and IgG were significantly increased in HCWs compared to general population (p= 0.028 for IgM and p= 0.002 for IgG). Conclusion: The frequency of SARS-CoV-2 specific antibodies in HCWs was higher than general population indicating a higher viral transmission via close exposure with COVID-19 patients.     

SARS-CoV-2 Seroprevalence among Healthcare Workers after the First and Second Pandemic Waves

Background: The Grand Hôpital de Charleroi is a large non-academic Belgian hospital that treated a large number of COVID-19 inpatients. In the context of this pandemic, all professions-combined healthcare workers (HCWs), and not only direct caregivers, are a frontline workforce in contact with suspected and confirmed COVID-19 cases and seem to be a high-risk group for exposure. The aim of our study was to estimate the prevalence of anti-SARS-CoV-2 antibodies in HCWs in our hospital after the first and second pandemic waves and to characterize the distribution of this seroprevalence in relation to various criteria. Methods: At the end of the two recruitment periods, a total of 4008 serological tests were performed in this single-center cross-sectional study. After completing a questionnaire including demographic and personal data, possible previous COVID-19 diagnostic test results and/or the presence of symptoms potentially related to COVID-19, the study participants underwent blood sampling and serological testing using DiaSorin’s LIAISON^® SARS-CoV-2 S1/S2 IgG test for the first phase and LIAISON^® SARS-CoV-2 TrimericS IgG test for the second phase of this study. Results: In total, 302 study participants (10.72%) in the first round of the study and 404 (33.92%) in the second round were positive for SARS-CoV-2-IgG antibodies. The prevalence of seropositivity observed after the second wave was 3.16 times higher than after the first wave. We confirmed that direct, prolonged, and repeated contact with patients or their environment was a predominant seroconversion factor, but more unexpectedly, that this was the case for all HCWs and not only caregivers. Finally, the notion of high-risk contact seemed more readily identifiable in one’s workplace than in one’s private life. Conclusions: Our study confirmed that HCWs are at a significantly higher risk of contracting COVID-19 than the general population, and suggests that repeated contacts with at-risk patients, regardless of the HCWs’ professions, represents the most important risk factor for seroconversion (Clinicaltrials.gov number, {"type":"clinical-trial","attrs":{"text":"NCT04723290","term_id":"NCT04723290"}}NCT04723290).     

Impact of the COVID-19 outbreak and the serum prevalence of SARS-CoV-2 antibodies in patients with inflammatory bowel disease treated with biologic drugs

BackgroundPatients receiving biologic therapies are at risk for viral infections. This study investigated the impact of the SARS-CoV-2 infection and the serum prevalence of SARS-CoV-2 antibodies in patients with inflammatory bowel disease (IBD) treated with biologic drugs.MethodsInformation on demography, co-morbidities, clinical data regarding IBD, symptoms suggestive of the SARS-CoV-2 infection, close contacts with SARS-CoV-2 positive patients, hospitalization, and therapies administered for COVID-19 was collected for all patients who were being treated with biologic drugs. All patients underwent SARS-CoV-2 antibody testing.ResultsTwo hundred and fifty-nine patients (27 children) with a mean age of 42.2 ± 16.7 years (range 9 - 88) and a mean duration of disease of 13.4 ± 10 years (range 0.2 – 49) were enrolled. One hundred four patients (40.2%) had ulcerative colitis, and 155 (59.8%) had Crohn's disease. About the therapy: 62 patients were receiving infliximab, 89 adalimumab, 20 golimumab, 57 vedolizumab, 27 ustekinumab, 1 thalidomide, and 3 an experimental compound. The mean Charlson Comorbidity Index was 2. Thirty-two patients (12.3%) reported respiratory symptoms, and 2 of them were hospitalized (0.77%). Two patients resulted positive for IgG against SARS-CoV-2 (0.77%).ConclusionsIn patients with IBD, treatment with biologic drug does not represent a risk factor for the SARS-CoV-2 infection.     

SARS Coronavirus-2 Microneutralisation and Commercial Serological Assays Correlated Closely for Some but Not All Enzyme Immunoassays

Serological testing for SARS-CoV-2-specific antibodies provides important research and diagnostic information relating to COVID-19 prevalence, incidence and host immune response. A greater understanding of the relationship between functionally neutralising antibodies detected using microneutralisation assays and binding antibodies detected using scalable enzyme immunoassays (EIA) is needed in order to address protective immunity post-infection or vaccination, and assess EIA suitability as a surrogate test for screening of convalescent plasma donors. We assessed whether neutralising antibody titres correlated with signal cut-off ratios in five commercially available EIAs, and one in-house assay based on expressed spike protein targets. Sera from recovered patients or convalescent plasma donors who reported laboratory-confirmed SARS-CoV-2 infection (n = 200), and negative control sera collected prior to the COVID-19 pandemic (n = 100), were assessed in parallel. Performance was assessed by calculating EIA sensitivity and specificity with reference to microneutralisation. Neutralising antibodies were detected in 166 (83%) samples. Compared with this, the most sensitive EIAs were the Cobas Elecsys Anti-SARS-CoV-2 (98%) and Vitros Immunodiagnostic Anti-SARS-CoV-2 (100%), which detect total antibody targeting the N and S1 antigens, respectively. The assay with the best quantitative relationship with microneutralisation was the Euroimmun IgG. These results suggest the marker used (total Ab vs. IgG vs. IgA) and the target antigen are important determinants of assay performance. The strong correlation between microneutralisation and some commercially available assays demonstrates their potential for clinical and research use in assessing protection following infection or vaccination, and use as a surrogate test to assess donor suitability for convalescent plasma donation.     

SARS-CoV-2 Seroprevalence Study in Pediatric Patients and Health Care Workers Using Multiplex Antibody Immunoassays

SARS-CoV-2 infection has become a global health problem specially exacerbated with the continuous appearance of new variants. Healthcare workers (HCW) have been one of the most affected sectors. Children have also been affected, and although infection generally presents as a mild disease, some have developed the Pediatric Inflammatory Multisystem Syndrome Temporally Associated with SARS-CoV-2 (PIMS-TS). We recruited 190 adults (HCW and cohabitants, April to June 2020) and 57 children (April 2020 to September 2021), of whom 12 developed PIMS-TS, in a hospital-based study in Spain. Using an in-house Luminex assay previously validated, antibody levels were measured against different spike and nucleocapsid SARS-CoV-2 proteins, including the receptor-binding domain (RBD) of the Alpha, Beta, Gamma, and Delta variants of concern (VoC). Seropositivity rates obtained from children and adults, respectively, were: 49.1% and 11% for IgG, 45.6% and 5.8% for IgA, and 35.1% and 7.3% for IgM. Higher antibody levels were detected in children who developed PIMS-TS compared to those who did not. Using the COVID-19 IgM/IgA ELISA (Vircell, S.L.) kit, widely implemented in Spanish hospitals, a high number of false positives and lower seroprevalences compared with the Luminex estimates were found, indicating a significantly lower specificity and sensitivity. Comparison of antibody levels against RBD-Wuhan versus RBD-VoCs indicated that the strongest positive correlations for all three isotypes were with RBD-Alpha, while the lowest correlations were with RBD-Delta for IgG, RBD-Gamma for IgM, and RBD-Beta for IgA. This study highlights the differences in antibody levels between groups with different demographic and clinical characteristics, as well as reporting the IgG, IgM, and IgA response to RBD VoC circulating at the study period.