High effectiveness of multimodal infection control interventions in preventing SARS-CoV-2 infections in healthcare professionals: a prospective longitudinal seroconversion study

ObjectiveTo assess the effectiveness of multimodal infection control interventions in the prevention of SARS-CoV-2 infections in healthcare professionalsDesignSequential follow-up studySettingLargest tertiary care centre in northern GermanyParticipants1253 employees of the University Medical Center Hamburg-Eppendorf were sequentially assessed for the presence of SARS-CoV-2 IgG antibodies at the beginning of the covid-19 epidemic (20 March – 9 April), one month (20 April – 8 May), and another two months later (22 June – 24 July). Of those, 1026 were healthcare workers (HCWs) of whom 292 were directly involved in the care of covid-19 patients. During the study period, infection control interventions were deployed, those included i) strict barrier nursing of all known covid-19 patients including FFP2 (N95) masks, goggles, gloves, hoods and protective gowns, ii) visitor restrictions with access control at all hospital entries, iii) mandatory wearing of disposable face masks in all clinical settings, and iv) universal RT-PCR admission screening of patients.Main Outcome MeasuresSARS-CoV-2 IgG seroconversion rateResultsAt the initial screening, ten participants displayed significant IgG antibody ratios. Another ten individuals showed seroconversion at the second time point one month later, only two further participants seroconverted during the subsequent two months. The overall SARS-CoV-2 seroprevalence in the study cohort at the last follow-up was 1.8%, the seroconversion rate dropped from 0.81% to 0.08% per month despite a longer observation period. Amongst HCWs seropositivity was increased in those directly involved in the care of patients with SARS-CoV-2 infections (3.8%, n=11) compared to other HCWs (1.4%, n=10, P=0.025). However, after the adoption of all multimodal infection control interventions seroconversions were observed in only two more HCWs, neither of whom were involved in inpatient care.ConclusionMultimodal infection control and prevention interventions are highly effective in mitigating SARS-CoV-2 infections of healthcare professionals.