At care institution De Tweemaster in Maassluis, ventilation was probably not the cause of the massive outbreak of the corona virus. In one department of the Tweemaster in Maassluis, seventeen residents and eighteen employees fell ill. The virus took the lives of six residents. RIVM previously published a report which stated that ventilation probably did play a role.
Two routes
GGD Rotterdam-Rijnmond coordinated the cluster investigation into the outbreak on behalf of all parties involved. This research shows that the virus entered the institution via two routes. Spread probably took place via an infected resident and / or employees. The ventilation systems have also been researched, but this does not seem to be the most obvious distribution route.
The investigation consisted of source and contact investigation, investigation of the ventilation system, infection prevention and sequencing. The latter is an investigation that examines whether multiple virus strains exist within an outbreak.
Various factors
There are several factors that could have contributed to this outbreak. Among other things, there were complaints from employees who were not recognized as COVID-19, so that the outbreak was found later than desired. Residents with complaints may have infected each other. Employees wore mouth-nose masks, but had lunch together and possibly infected each other because keeping their distance was not always possible. Since the virus mainly spreads via large droplets, these are more likely routes of distribution.
Ventilation system
The ventilation system within the healthcare facility has also been investigated. A very small amount of viral RNA was found in dust samples taken from the ventilation outlet in two rooms of patients. This was also the case in the discharge of a ventilation system in a shared living room where the patient, who was infected with the corona virus, was regularly present. The study was unable to detect infectious viruses on the samples collected from the ventilation systems. It therefore appears that the ventilation system is not the most likely contamination route in this outbreak.
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