INFECTION PREVENTION AND CONTROL Zoonotic


SARS-CoV-2 (Formerly 2019-n-CoV)


Foodborne? Close contact?


Small droplets <5–<50 μm


Larger droplets <50–<100 μm


Direct contact Blood tranfusion? Transplacental? Human-to-human


Accidental laboratory exposure?


Direct contact with contaminated surfaces


Organ transplantation? Perinatal?


Fig 5: Different methods of transmission of the SARS-CoV-2 virus.


time’ must be taken into account. Contact time is the amount of time that the virus needs to be in contact with the particular product in order for that product to inactivate it. For stronger disinfectants, or stronger UV lights, this can be a very short period of time – sometimes less than a second, while for ‘weaker’ products it may be several minutes.


In the case of UV systems for air- handling, there are two very different products available, each with different uses. The type that shine UV light on to the air offside of the coils are very effective at preventing mould and bacteria growing on the coils, as such lights are continuously shining a weaker UV on to the coils – a weak disinfection, but with a high contact time for the coils. However, this type of UV light will not have any effect on a virus particle in the air stream flowing past it, as the contact time with the light is insufficient to destroy the virus. The much stronger UV in-duct systems will have an impact on bacterial, fungal, and viral particles in the air flowing past, since although the contact time is short, the UV is very strong. Silver-coated filters are another illustration of this – the filter itself may be protected from growth of bacteria and fungi, but it is very unlikely to have any effect on virus flowing past in the air, for two reasons: firstly, the contact time is very short, and, secondly, the silver coating is likely to become coated with dust very quickly, which means air will not be in contact with the silver coating at all. Ionisation systems may help, as they physically remove the virus particles from the air along with dust and other contaminants, but more evidence is needed. There have been a disappointing number of ineffective products being marketed to ‘concerned consumers’ during the pandemic. Adding products such as tea tree oil or other disinfectants to an air-handling system is not only likely to be ineffective, but may also increase


26 Health Estate Journal May 2021


allergies and odour complaints among staff in a healthcare facility.


Cleaning


At the start of the pandemic, much was made of the vital contribution of cleaning and disinfection, and both are important. However, and thankfully the practice appears to have decreased in popularity, there is no place for fogging with disinfectants outside of the already established fogging protocols used in a hospital setting for infection control (and some food production settings). Fogging of offices and shops – and especially streets and people – has no place in preventing coronavirus transmission, and may indeed have adverse health effects. Pictures of streets being sprayed with disinfectants are either misguided, or an exercise in making the public feel that something is being done. The key priority for cleaning and disinfection is that cleaning must always be carried out first – as disinfection will only work effectively on a clean surface. Dirt inactivates disinfectants, and so spraying dirty surfaces, or adding disinfectants to dusty air-conditioning ductwork, ensures that the disinfectant will not be effective. As described earlier in this article, soap or detergent alone do a fantastic job of deactivating viral particles. Within a hospital, thankfully, established cleaning protocols will be in place, with hospital grade disinfectants and detergents, so hopefully the more ‘interesting’ formulations of cleaning products we have seen have not made it into hospitals and aged care settings. Again, here simplicity is key, with using old-fashioned soap (detergent) and water being the best approach.


Travel restrictions Another intervention that has undoubtedly helped Australia avoid the worst of the pandemic has been the


restriction and quarantining of inbound travellers. This began with travellers from China being blocked on 1 February 2020, and from Iran, South Korea, and Italy, shortly afterwards. This was followed by a two-week home quarantine for all travellers from 15 March 2020, made stricter with two weeks’ supervised hotel quarantine for all inbound travellers from 27 March last year. Australia’s borders closed to foreign travellers on 20 March 2020, and have not reopened at present. State and Territory borders within the country have also been closed for parts of the year to prevent spread within Australia. This decreased the potential for spread of the virus from returning travellers to the community. Although hotels are not ideal quarantine facilities – because they were never designed to be a quarantined facility, they do appear to have functioned very well in this role, with very few infections escaping to staff or the community – although the number of quarantined staff becoming infected does appear to have (anecdotally) increased with the UK variant entering the country, with Perth, Melbourne, and Brisbane having recent short lockdowns. Australia has recorded just over 29,000 infections and 909 deaths since the first recorded cases on 25 January 2020 at the time of writing, and has begun vaccine roll-out.


Vaccines


Thankfully, several vaccines have been developed and approved for use throughout the world, with the Pfizer and Astra Zeneca vaccines currently approved and being rolled out in Australia. These have been developed in record time, which has caused concern in some groups. The rapid development has mainly been due to the cessation of development of any other vaccines by drug companies, the investment of millions of dollars worldwide, and the prioritisation of assessing the vaccines by regulatory


American Society for Microboiology


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