The Brussels University Hospital, also a reference center for infectious diseases, tested 326 members of its staff by PCR and serological tests. This 6-month study has just revealed its first preliminary results : in units linked to COVID, one in eight staff members, or 12.6% (41 people), was positive.
First 2 phases
At the peak of the SARS-CoV-2 epidemic, some 700 people worked in COVID-19 units (7 units and 125 beds, reserved for probable or confirmed patients), in COVID-19 Intensive Care (2 units totaling 33 beds ) and Emergency. All were invited to participate on a voluntary basis in a 6-month study, to detect their possible infection and immune reaction to the SARS-COv-2 virus. Whether or not symptoms were present was not a criterion. 6 sessions of PCR and serological tests were planned. This preliminary report addresses the results obtained during the first two phases, on the 1st day of the study, and on the 15th.
Several categories of personnel
A total of 532 workers agreed to participate. Among them, 85 doctors, 150 nurses, 60 paramedics, 25 administrative workers, 6 stretcher bearers and cleaners. Between April 15 and May 18, 326 of them attended the first two test visits. 17.1% reported symptoms suggestive of Covid-19. In total, 41 cases were confirmed by PCR tests and / or serological test, representing an infection rate of 12.6%.
Neither gender, nor age, nor the function exercised (whether in direct contact with the patient or not) represented a particular risk factor. Charlotte Martin, infectious disease specialist and first author of the study with Isabel Montesinos: “The study shows that people who entered the rooms were no more infected than others. This shows that the protective measures have been effective at this level. However, question: where did we get infected? One hypothesis is that it happened between staff members, because we did not have enough masks for everyone in the hospital to wear a universal mask before April 1. We did all the climb to the peak without a universal mask in the hospital.”
However, the test was more likely to be positive if the person had one or more symptoms, or a comorbidity. The seroprevalence (presence of antibodies) was 2.5 times higher (11 and 12% on days 1 and day 15) than in Belgian blood donors during the same period (4.3%).
In this cohort of young people (average age = 37 years) and in good health (11% comorbidity), the infection was in the majority of cases mild and without fever. It is interesting to note that 75% of the participants with a positive PCR test were asymptomatic.
The authors of this preliminary report conclude that it is important to test hospital staff for both the presence of the infection (PCR tests) and antibodies (serological tests), because in this study, 62.5% of SARS-CoV2 infections would have been missed if only PCR tests had been performed.
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