‘Super-spreader’ areas identified in health settings: Study

When it comes to reducing the spread of airborne viruses, such as COVID-19, there are multiple strategies, from PPE use and social distancing to vaccination.
 
However, improving ventilation to reduce the viral particles in a space – arguably one of the most effective ways to mitigate spread – is often the most overlooked.
 
But new Australian research has found that there is a simple and inexpensive way to identify high-risk areas quickly and accurately: CO2 monitors.
 
Published in Age and Ageing, researchers from the South Australian Health and Medical Research Institute (SAHMRI) and Flinders University demonstrated this by assessing a residential aged care facility (RACF) in Adelaide.
 
Over a four-week period, 62 CO2 sensors were deployed across 25 communal rooms, 17 staff-only areas, and 20 connecting sites, such as corridors and lifts. During the study period, all staff and visitors were required to wear N95 face masks (or equivalent), goggles or a face shield, and be vaccinated against COVID-19.
 
Of the 45 monitors in mixed zones (accessed by both staff and residents), none showed indications of poor ventilation. However, of the 17 staff-only zones, three (17.6%) were identified as having a high airborne infection transmission risk, including one staff lunchroom and two staff meeting rooms.
 
Co-author of the study, Dr Steven Taylor, told newsGP that as well as being highly frequented areas, it is human nature that staff may become less mindful of the transmission risk when in a space, such as a staff tearoom, that is not patient-facing.
 
‘Definitely in healthcare settings when you’re in the wards or clinic rooms you’re a lot more conscious of your interactions with patients,’ he said.
 
‘But the person-to-person spread between healthcare staff is also definitely something to consider, and it’s often something that is not at the front of everyone’s mind.’
 
To be considered a high-transmission risk, zones were identified based on CO2 levels exceeding 1000 parts per million (ppm) for a period of 15 minutes or more.
 
Once these areas were identified, Dr Taylor and his colleagues worked alongside the RACF to deploy simple targeted strategies to improve ventilation, starting with the installation of an extraction fan in the staff tearoom.
 
‘The staff tearoom has quite a high density of people that come through, particularly around lunchtime and dinnertime to eat their food, and we found that those areas had quite high peaks around those times,’ he said.
 
‘We were able to put in an exhaust fan quite simply and cheaply into that area, which increased the airflow and the amount of outdoor air that was able to circulate into that room – and it really reduced the risk of infection spread in that area.’
 
Other areas identified as high risk were meeting rooms. There they found existing ducted air conditioning systems that could be more effectively used by pre-programming them to ensure optimal air quality.
 
‘A lot of the time you go into a meeting room, it’s not really used, and you think to turn on the lights, but you don’t think to turn on the air conditioning,’ Dr Taylor said.
 
‘So we just set up automatic timing for those. Again, a very simple strategy that meant that across work hours, those rooms were not risks of transmission of respiratory viruses.’
 
While the study’s focus was an RACF, Dr Taylor says use of CO2 monitors to identify any high-risk areas and implement similarly simple strategies can be applied to other healthcare settings, including general practices.
 
‘Particularly if they’re buildings or sites where you don’t have a good overview of the ventilation strategies already, it can be a great way to quite rapidly and cheaply survey a site and actually see what’s going on within an area,’ he said.
 
‘And you might already hypothesise that an area like a tearoom gets busy around lunchtime, but it allows you to be able to put a number to that risk.’
 
While infection control practices are well-established, Dr Taylor says the most effective are those that do not require a change in human behaviour, but rather an environmental change to improve ventilation.
 
He says this is particularly important in the context of pandemic fatigue, as we prepare to enter a fourth year of living with COVID-19.
 
‘What COVID really taught us was the particular settings that are extra vulnerable … particularly indoor spaces where there’s a high density of vulnerable people,’ Dr Taylor said.
 
‘Moving forward … I think it’s unreasonable to expect masks and behavioural practices to be the sole focus to try and limit infection spread.
 
‘Looking at other alternatives like ventilation has been shown to be a very effective strategy.’
 
For more information and guidance on infection control, members can access the RACGP’s Infection prevention and control guidelines.
 
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