SARS-CoV-2 RBD-specific and NP-specific antibody response of healthcare workers in the westernmost Austrian state Vorarlberg: a prospective cohort study

Abstract

ObjectivesAustria, and particularly its westernmost federal state Vorarlberg, developed an extremely high incidence rate during the COVID-19 pandemic. Healthcare workers (HCWs) worldwide are known to have an increased risk of contracting the disease within the working environment and, therefore, the seroprevalence in this population is of particular interest. We thus aimed to analyse SARS-CoV-2-specific antibody dynamics in Vorarlberg HCWs.DesignProspective cohort study of HCWs including testing at three different time points for the prevalence of anti-SARS-CoV-2 IgG antibodies specific for nucleocapsid protein (NP) and receptor-binding domain (RBD).SettingAll five state hospitals of Vorarlberg.ParticipantsA total of 395 HCWs, enrolled in June 2020 (time point 1 (t1)), 2 months after the end of the first wave, retested between October and November at the beginning of the second wave (time point 2 (t2)) and again at the downturn of the second wave in January 2021 (time point 3 (t3)).Main outcomesWe assessed weak and strong seropositivity and associated factors, including demographic and clinical characteristics, symptoms consistent with COVID-19 infection, infections verified by reverse transcription PCR (RT-PCR) and vaccinations.ResultsAt t1, 3% of HCWs showed strong IgG-specific responses to either NP or RBD. At t2, the rate had increased to 4%, and at t3 to 14%. A strong response was found to be stable for up to 10 months. Overall, only 55% of seropositive specimen had antibodies against both antigens RBD and NP; 29% had only RBD-specific and 16% only NP-specific antibodies. Compared with the number of infections found by RT-PCR, the number of HCWs being seropositive was 38% higher.Conclusion and relevanceSerological testing based on only one antigen implicates the risk of missing infections; thus, the set of antigens should be broadened in the future. The seroprevalence among participating HCWs was comparable to the general population in Austria. Nevertheless, in view of undetected infections, monitoring and surveillance should be reconsidered.

SARS-CoV-2 infections in “less visible” hospital staff: The roles and safety of environmental services and allied health professionals

“…In our Austrian HCW groups, which included environmental services and allied health professionals, 7.7% of the participants had IgG antibodies against SARS-CoV-2, indicating relevant prior contact with the virus. In comparison, the percentage of SARS-CoV-2 seropositive HCWs rose to 14% in the south-western parts of Austria, which were most affected by the pandemic [22] . The general SARS-CoV-2 seroprevalence for Austria was estimated to be 4.7% by April 2021 (Statistic Austria Report; [23] , [24] .…”

“…The authors of these reports concluded that the differences in seroprevalence resulted from the availability of and compliance to respective precaution measures [25] . Other authors reported that, with increasing community infection numbers, the seroprevalence of SARS-CoV-2 in HCWs rose similarly [22] , [26] . In our study, we aimed to describe risk factors regarding occupational safety and health in our specific HCW groups.…”

“…Secondly, SARS-CoV-2 IgG antibodies have their known limitations as infection markers; even though not every COVID-19 patient develops antibodies against the disease, persisting antibodies are a good marker for prior infection or for even just SARS-CoV-2 exposure. In a seroprevalence study from Austrian state Vorarlberg [22] , the number of healthcare workers with positive SARS-CoV-2 IgG was 38% higher than that of healthcare workers who had a positive PCR test. These data, as well as our findings, were derived before the introduction of vaccines for these specific groups.…”