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CDC the latest to acknowledge COVID aerosol spread


Matt Woodley


8/10/2020 3:42:23 PM

Unlike most parts of Australia, the US public health agency recommends the use of N95 or equivalent respirators when treating suspected cases.

SARS-CoV-2 virus particles
The CDC says coronavirus can spread distances greater than six feet (1.82 m) through the air. (Image: AAP)

The US Centers for Disease Control and Prevention (CDC) has again acknowledged the potential airborne spread of coronavirus, two weeks after back-flipping on a prior claim that supported the controversial theory.
 
Similar to guidelines issued by the Communicable Diseases Network Australia (last updated on 24 August), the new CDC guidance advises most infections are spread through close contact, not airborne transmission.
 
However, it goes on to state that airborne transmission of SARS-CoV-2 can occur under ‘special circumstances’, prompting warnings about enclosed spaces, prolonged exposure to respiratory particles through activities such as singing or shouting, and spaces with inadequate ventilation.
 
‘There are several well-documented examples in which SARS-CoV-2 appears to have been transmitted over long distances or times,’ the guidance states.
 
‘These transmission events appear uncommon and have typically involved the presence of an infectious person producing respiratory droplets for an extended time [>30 minutes to multiple hours] in an enclosed space.
 
‘Enough virus was present in the space to cause infections in people who were more than six feet [1.8 m] away or who passed through that space soon after the infectious person had left.’
 
Conversely, Australian guidelines only list airborne transmission as a threat during aerosol-generating procedures such as bronchoscopy or intubation, while official social-distancing advice only mandates 1.5 m of separation, regardless of setting. 
 
Australia’s Infection Control Expert Group (ICEG), which determines national coronavirus advice provided to public health units, has previously dismissed the threat of airborne transmission as having ‘minimal’ clinical significance, despite concerns that it contributed to high rates of COVID infection among Victorian healthcare workers.
 
ICEG Chair Professor Lyn Gilbert previously told newsGP that protection from COVID-19 depends on a ‘hierarchy of precautions’, and while that includes the use of face masks it is ‘not necessarily the most important’ nor adequate on its own.
 
‘Fresh air or good ventilation, physical distancing or physical barriers, and cough or respiratory and hand hygiene are the most important precautions,’ she said.
 
However, the Victorian Government responded to the state’s recent soaring infection rate by unilaterally upgrading its own infection control advice, basing its measures on the assumption that COVID is ‘everywhere’ and likely able to be transmitted through aerosols.
 
Following the CDC’s recent update, this Victorian approach – and the requirement to use N95/P2 respirators when caring for suspected or confirmed COVID cases in certain settings – is now closer to the one being adopted in the US than in other parts of Australia.
 
‘[Healthcare workers] who enter the room of a patient with suspected or confirmed SARS-CoV-2 infection should adhere to Standard Precautions and use a NIOSH-approved N95 or equivalent or higher-level respirator [or facemask if a respirator is not available], gown, gloves, and eye protection,’ the CDC advice states.
 
‘When available, respirators [instead of face masks] are preferred.’
 
The Australian Government also responded to the high rates of healthcare worker infection by announcing in early September that ICEG would partner with the National COVID-19 Evidence Taskforce to review the latest evidence and ‘help reduce the number of healthcare workers being infected with COVID-19’.
 
However, nearly one month later no new updates or advice have been released by the new partnership.
 
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