Photo Credit PHIL
#15,351
The debate over whether COVID-19 is a truly `airborne' pathogen has continued almost since the virus first emerged, and while there isn't definitive, replicable proof, the evidence gets stronger with every passing week.
Back in February, the CDC warned:
Although routes of transmission have yet to be definitively determined, CDC recommends a cautious approach to interacting with patients under investigation. Ask such patients to wear a face mask as soon as they are identified. Conduct patient evaluation in a private room with the door closed, ideally an airborne infection isolation room, if available. Personnel entering the room should use standard precautions, contact precautions, and airborne precautions, and use eye protection (goggles or a face shield). For additional healthcare infection control recommendations, visit CDC's Infection Control webpage.
Many observers saw the rapid spread of the virus aboard the Diamond Princess cruise ship in Japan as suggestive of airborne spread (see CDC HAN #00430: Guidance about Global Travel on Cruise Ships), and a number of `super spreading' events in restaurants, churches, and other large gatherings have added to those suspicions.
MMWR: High COVID-19 Attack Rate Among Attendees at Events at a Church
MMWR Early Release: COVID-19 Superspreading Event In A Church Choir
Environmental studies have consistently found evidence of SARS-CoV-2 contamination in rooms occupied by infected patients (even asymptomatic cases), and often many yards away, either carried by air drafts or transferred by people and/or materials that had close contact with an infected person.
EID Journal: Prolonged Infectivity of SARS-CoV-2 in Fomites
EID Journal: Persistence of SARS-CoV-2 in Aerosol Suspensions
EID Journal: Detection of SARS-CoV-2 on Surfaces in Quarantine Rooms
EID Journal: Aerosol and Surface Distribution of SARS-CoV-2 in Hospital Wards, Wuhan, China
Despite this preponderance of evidence, the World Health Organization continues to discount the role that aerosolized virus particles may play in the spread of the pandemic, and bases their infection control advice on the assumption that direct contract, large droplets, and possibly transfer from fomites are the primary drivers of transmission.
This week, 200+ scientists from around the world signed an open letter to the WHO, urging them to reconsider their stance on the airborne spread of the virus.
It is Time to Address Airborne Transmission of COVID-19
Lidia Morawska, Donald K Milton
Clinical Infectious Diseases, ciaa939, https://doi.org/10.1093/cid/ciaa939
As with most of the other studies of this type, the virus was detected by RT-PCR, which does not indicate its viability. Researchers tried, but were unable to live culture the virus from the samples taken.
I've only included the abstract and a small excerpt, so follow the link to read it in its entirety.
Long-distance airborne dispersal of SARS-CoV-2 in COVID-19 wards
Karolina Nissen, Janina Krambrich, Dario Akaberi, Tove Hoffman, Jiaxin Ling, Åke Lundkvist, Erik Salaneck
DOI:10.21203/rs.3.rs-34643/v1
Abstract
Evidence suggests that SARS-CoV-2 can be dispersed and potentially transmitted by aerosols, directly or via ventilation systems. We report detection of SARS-CoV-2 RNA in COVID-19 ward ceiling vent openings as well as in ventilation exhaust filters and central ducts up to at least 56 meters from patient areas. As this ventilation system provides low air flow, we propose that viral particles may be readily dispersed in air over vast distances and that further investigations of infectivity of airborne SARS-CoV-2 must be performed.
(SNIP)
In this study, we found SARS-CoV-2 RNA in vent openings in ward rooms harboring COVID-19 patients. Viral RNA was also detected in fluid placed in open dishes suspended below vent openings. Similar levels of viral RNA were detected in exhaust filters and open petri dishes with cell medium at least 44 to 56 meters from the COVID-19 wards. Only a small fraction of each filter was analyzed implying that the large number of particles emanating from COVID-19 wards can disperse to greater distances than can be explained by droplet transmission routes.
In previous studies, the effect of ventilation has not shown any obvious impact on the risk for spread of droplet-transmitted diseases, probably since droplets are more governed by gravity15. Furthermore, the ventilation system in the investigated hospital building has a relatively low air flow; between 1,7 and 3 total air changes per hour (ACH) for each room, depending on room volumes. The recommendation for airborne isolation rooms is 12 ACH in most guidelines15.
(Continue . . . )
Almost every step of the way, the world has underestimated the SARS-CoV-2 virus, and has been slow to react.
- Even while the virus was spreading in Europe, and had landed in the United States, most officials believed the virus was still `contained' in China.
- Asymptomatic spread of the virus was considered unlikely early in the pandemic, and so asymptomatic cases weren't treated as a threat.
- Masks and face coverings for the public - at least in the Western world - were deemed unnecessary for months, and only reluctantly adopted in April by the United States, and not until June by the WHO (see COVID-19: WHO Changes Face Mask Policy For General Public).
While incontrovertible evidence regarding airborne transmission would be nice to have, waiting for scientific certainty continues to put healthcare workers - and others - at risk.
In the midst of a pandemic, we can't afford to fiddle while the virus burns.
