<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Laure Mortgat</style></author><author><style face="normal" font="default" size="100%">Kristien Verdonck</style></author><author><style face="normal" font="default" size="100%">Veronik Hutse</style></author><author><style face="normal" font="default" size="100%">Isabelle Thomas</style></author><author><style face="normal" font="default" size="100%">Cyril Barbezange</style></author><author><style face="normal" font="default" size="100%">Heyndrickx, Leo</style></author><author><style face="normal" font="default" size="100%">Nathalie Fischer</style></author><author><style face="normal" font="default" size="100%">Vuylsteke, Bea</style></author><author><style face="normal" font="default" size="100%">Ines Kabouche</style></author><author><style face="normal" font="default" size="100%">Ariën, Kevin K</style></author><author><style face="normal" font="default" size="100%">I Desombere</style></author><author><style face="normal" font="default" size="100%">Els Duysburgh</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Prevalence and incidence of anti-SARS-CoV-2 antibodies among healthcare workers in Belgian hospitals before vaccination: a prospective cohort study.</style></title><secondary-title><style face="normal" font="default" size="100%">BMJ Open</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Adult</style></keyword><keyword><style  face="normal" font="default" size="100%">Belgium</style></keyword><keyword><style  face="normal" font="default" size="100%">COVID-19</style></keyword><keyword><style  face="normal" font="default" size="100%">Female</style></keyword><keyword><style  face="normal" font="default" size="100%">Health Personnel</style></keyword><keyword><style  face="normal" font="default" size="100%">hospitals</style></keyword><keyword><style  face="normal" font="default" size="100%">Humans</style></keyword><keyword><style  face="normal" font="default" size="100%">incidence</style></keyword><keyword><style  face="normal" font="default" size="100%">prevalence</style></keyword><keyword><style  face="normal" font="default" size="100%">Prospective Studies</style></keyword><keyword><style  face="normal" font="default" size="100%">SARS-CoV-2</style></keyword><keyword><style  face="normal" font="default" size="100%">Seroepidemiologic Studies</style></keyword><keyword><style  face="normal" font="default" size="100%">Vaccination</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2021</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2021 06 29</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">11</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;&lt;b&gt;OBJECTIVES: &lt;/b&gt;To describe prevalence and incidence of anti-SARS-CoV-2 antibodies among Belgian hospital healthcare workers (HCW) in April-December 2020.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;DESIGN: &lt;/b&gt;Prospective cohort study. Follow-up was originally planned until September and later extended.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;SETTING: &lt;/b&gt;Multicentre study, 17 hospitals.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;PARTICIPANTS: &lt;/b&gt;50 HCW were randomly selected per hospital. HCW employed beyond the end of the study and whose profession involved contact with patients were eligible. 850 HCW entered the study in April-May 2020, 673 HCW (79%) attended the September visit and 308 (36%) the December visit.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;OUTCOME MEASURES: &lt;/b&gt;A semiquantitative ELISA was used to detect IgG against SARS-CoV-2 in serum (Euroimmun) at 10 time points. In seropositive samples, neutralising antibodies were measured using a virus neutralisation test. Real-time reverse transcription PCR (RT-qPCR) was performed to detect SARS-CoV-2 on nasopharyngeal swabs. Participant characteristics and the presence of symptoms were collected via an online questionnaire.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;RESULTS: &lt;/b&gt;Among all participants, 80% were women, 60% nurses and 21% physicians. Median age was 40 years. The seroprevalence remained relatively stable from April (7.7% (95% CI: 4.8% to 12.1%) to September (8.2% (95% CI: 5.7% to 11.6%)) and increased thereafter, reaching 19.7% (95% CI: 12.0% to 30.6%) in December 2020. 76 of 778 initially seronegative participants seroconverted during the follow-up (incidence: 205/1000 person-years). Among all seropositive individuals, 118/148 (80%) had a positive neutralisation test, 83/147 (56%) presented or reported a positive RT-qPCR, and 130/147 (88%) reported COVID-19-compatible symptoms at least once. However, only 46/73 (63%) of the seroconverters presented COVID-19-compatible symptoms in the month prior to seroconversion.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;CONCLUSIONS: &lt;/b&gt;The seroprevalence among hospital HCW was slightly higher than that of the general Belgian population but followed a similar evolution, suggesting that infection prevention and control measures were effective and should be strictly maintained. After two SARS-CoV-2 waves, 80% of HCW remained seronegative, justifying their prioritisation in the vaccination strategy.&lt;/p&gt;

&lt;p&gt;&lt;b&gt;TRIAL REGISTRATION NUMBER: &lt;/b&gt;NCT04373889.&lt;/p&gt;
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