Positive no-touch surfaces and undetectable SARS-CoV-2Positive no-touch surfaces and undetectable SARS-CoV-2 aerosols in long-term care facilities: An attempt to understand the contributing factors and the importance of timing in air sampling campaigns
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7879049/ Funding: This work was supported by the Fonds de recherche du Qubec -Sant (COVID-19 Pandemic Initiative funds), the Institut de Recherche Robert-Sauv en Sant et en Scurit du Travail du Qubec (IRSST 2017-0004), Toronto COVID-19 Action Initiative (University of Toronto) and Questcap Inc. Sponsors had no direct role in the design of the study or the publishing process. CD is the holder of Tier-1 Canada Research Chair on Bioaerosols.
Between December 2019 and January 2021, the coronavirus (COVID-19) pandemic caused by the Severe Acute Respiratory coronavirus type 2 (SARS-CoV-2) resulted in nearly 100 million confirmed cases and 2 million deaths.
1 People above 65 years old were 5-13 times more likely to be hospitalized and 90 to 630 times more likely to die from the disease than individuals between the age of 18 and 29 years old.
2 The oldest and most frail seniors require hours of daily assistance and many reside in long-term care facilities (LTCFs) where outbreaks of viral respiratory (influenza) and gastrointestinal tract infections (norovirus) are common
3. SARS-CoV-2 transmission in LTCFs has also been reported worldwide, including in the United States,
4 the Netherlands
5 and Canada.
6 SARS-CoV-2 outbreaks are more likely to happen in confined/crowded congregate living spaces like LTCFs, nursing homes and prisons than traditional living spaces.
7 , 8 People living in LCTFs generally have limited mobility, live in close proximity to each other, and require close contact with care personnel, leading to increased number of potential transmission events.
Knowledge of SARS-CoV-2 spread is incomplete and it is still not clear how the virus is transmitted in LTCFs, particularly when recommended infection prevention strategies appear to be properly applied. Public health organizations recognized respiratory droplets and aerosols as major transmission routes for the virus.
9 , 10 Although SARS-CoV-2 virus preserves infectivity for days on various surfaces
11 , 12 and in the air,
13 no specific report clearly supports that COVID-19 can be transmitted via fomites, and it is not considered to be the main route of transmission.
14 , 15 On the other hand, it was suggested that aerosols (short or long distance transmission) could be involved in the transmission of COVID-19.
16, 17, 18, 19, 20 Indeed, it was reported that coughing, sneezing, talking or even breathing can lead to emission of SARS virus aerosols in both respirable and inhalable sizes.
21, 22, 23 Aerosols from various sizes (inhalable, thoracic and respirable) can be produced and enter the respiratory tract.
24, 25, 26, 27, 28 Since both SARS-CoV-1 and SARS-CoV-2 are phylogenetically highly similar, it seems possible that COVID-19 may also be spread by small particle aerosols.
29 Nonetheless, it is not clear how the emission of SARS-CoV-2 aerosols is modulated in both symptomatic and asymptomatic infected people. It seems that the earlier stages of COVID-19 are associated with emission rates as high as 10
5 viral RNA copies per min.
30 Accurate information about airborne concentrations of SARS-CoV-2 is still sparse and no standardized or reference sampling and detection methods have been validated for this purpose.
31 Published reports have used various approaches of air and no-touch surface sampling but experimental parameters are sometimes ill-defined, such as particle sizes and concentrations, air sampling and downstream processing (type of sampler, sampled volume, nucleic acid purification, real-time reverse transcription polymerase chain reaction (RT-qPCR)), environmental parameters (high/low risk areas, air exchange rates, sampler position/location), and presence and type of aerosols generating procedures (AGP). In addition, the contribution to viral aerosolization of common interventions in LCTF such as the use of continuous positive airway pressure (CPAP) machines or toilet flushing were not described in the COVID literature, nor was the impact of poor ventilation. All these limitations and differences in experimental approaches complexify interpretation and make it difficult to generalize published knowledge to long-term-care facilities.
31 Nonetheless, these studies report positive air samples and no-touch surfaces in healthcare settings (≈8% to 100% positive),
30 , 32, 33, 34, 35, 36, 37 suggesting SARS-CoV-2 may be aerosolized in COVID-19 LCTFs.
Other than control and prevention measures such as personal protective equipment and personal hygiene, appropriate ventilation should limit the spread of COVID-19.
38 de Man et al reported that inadequate ventilation in a nursing home building led to an outbreak that stemmed from aerosol transmission of SARS-CoV-2.
39 It was also stated in the press that broken ventilation (100% recirculation) could have allowed the aerosols to concentrate and spread in the building causing at least 200 cases and 64 deaths among the 236 residents.
40 This prospective study was conducted to determine air and no-touch surface contamination by SARS-CoV-2 in LCTFs with COVID-19 outbreaks during spring 2020. Air and no-touch surface samples were simultaneously taken in COVID-19 positive patients’ rooms. Contributing factors to the presence of SARS-CoV-2 aerosols in these healthcare settings were investigated and the outbreak calendar was obtained after the sampling visits. This paper adds knowledge that could help limit propagation of COVID-19 among resident and healthcare workers in LTCFs.