key: cord-335907-93gwmo0v
authors: de Man, Peter; Paltansing, Sunita; Ong, David S Y; Vaessen, Norbert; van Nielen, Gerard; Koeleman, Johannes G M
title: Outbreak of COVID-19 in a nursing home associated with aerosol transmission as a result of inadequate ventilation
date: 2020-08-28
journal: Clin Infect Dis
DOI: 10.1093/cid/ciaa1270
sha: 
doc_id: 335907
cord_uid: 93gwmo0v

nan

M a n u s c r i p t Dear editor, With great interest we read the appeal to address airborne transmission of COVID-19 by Morawska and Milton in your journal [1] . Recently, we were involved in an outbreak in a Dutch nursing home that was likely to be the result of aerosol transmission in a setting of inadequate ventilation. This outbreak therefore illustrates the risks for which the authors are warning us.

In total, 17 (81%) residents from one of the seven wards in a nursing home with psychogeriatric residents were diagnosed with COVID-19 as confirmed by RT-PCR ( Figure 1 ) [2] . Subsequently, 17 (50%) healthcare workers (HCWs) of the same ward were also tested positive. In contrast, all tests of the 106 HCWs or 95 residents in the 6 other wards were negative. In the week of this outbreak a low prevalence of COVID-19 was reported, only 493 (0.77%) positive cases were detected in the Netherlands, whereas the weekly rate was 8391 (21.5%) during the national peak in April 2020 [3].

To prevent and control COVID-19 infections all HCWs in this nursing home had been assigned to specific wards and did wear surgical masks during patient contacts since April 26, 2020 [4] . HCWs did not wear masks during not patient related activities and breaks.

Residents were housed in individual rooms and spend part of the day in shared living rooms, some residents were mobile. Therefore, contact and thus direct transmission between residents cannot be excluded.

Because of the remarkable increase of COVID-19 infections in a very short time period despite the use of surgical masks, the ventilation system of the outbreak ward was investigated in addition to routine source and contact tracing. This ward was renovated, including the installation of a CO 2 controlled energy-efficient ventilation system. In this A c c e p t e d M a n u s c r i p t system, the indoor air was only refreshed with outside air based on real time CO 2 concentration measurements. If the CO 2 concentration did not exceed 1000 ppm, the ventilation cabinets recirculated indoor air back into the ward without filtration. In this situation, low CO2 production by inactive nursing home patients might have limited the ventilation with outside air. Moreover, this ward was additionally cooled by two air conditioning units, which recirculated air through a 1 mm mesh dust filter. In contrast, the other six wards were ventilated with outside air. A c c e p t e d M a n u s c r i p t

None to declare M a n u s c r i p t 

It is Time to Address Airborne Transmission of COVID-19

Detection of 2019 novel coronavirus (2019-nCoV) by real-time RT-PCR

Current information about the novel coronavirus (COVID-19) Bilthoven: RIVM

Allowing Visitors Back in the Nursing Home During the COVID-19 Crisis: A Dutch National Study Into First Experiences and Impact on Well-Being

M a n u s c r i p t