Research

‘Scarily fleeting’ contact with variant may infect

The transmission advantage of the Delta variant of COVID is a sign that the race between vaccination and the virus could tip in favour of the latter unless countries ramp up their immunisation campaigns and practise caution, scientists have warned. 

Research conducted in the UK, where the variant accounts for 99 per cent of new COVID cases, suggests it is about 60 per cent more transmissible than the Alpha variant, which previously dominated. It may also be linked to a greater risk of hospitalisation and is more resistant to vaccines, particularly after one dose. Of real concern is news from the UK: Prime Minister Boris Johnson has confirmed that face masks will soon no longer be legally required and distancing rules will be scrapped at the final stage of England's COVID lockdown roadmap.

Health officials here in Australia, reviewing CCTV footage from Sydney, suspect it has been transmitted in “scarily fleeting” encounters of roughly five to 10 seconds between people walking past each other in an indoor shopping area in Sydney, New South Wales. Cases have also been recorded in the Northern Territory, Queensland and Western Australia, with several large cities either in lockdown now or just having come out of it. The Delta outbreak in the Northern Territory spread from a mining camp and now poses significant risk to the community, officials said. This is what Victoria's Chief Medical Officer, Brett Sutton, warned a few weeks ago.

Dr Stephen Griffin, a virologist at the University of Leeds school of medicine, commented: “The ideal scenario is that you build your vaccine wall before you get exposed to variants because that means that even if you do get an outbreak, you’ve got sufficiently few people that are susceptible that the R [reproduction number] never gets above 1, you don’t see an increase in that outbreak. The problem is that we haven’t reached that protective level, and so if you do get infections and cases growing there’s plenty of susceptible people to pass that infection on to.” He told the Guardian the evidence suggests “we must go belt and braces in all of this. There’s no point leaving it half done – we can’t ignore children in vaccination campaigns. If we do, then we could end up in a cycle of variants.” Read more: Variants: distribution of case data, 18 June 2021, PHE, updated 25 June 2021. ACTU news releaseBMJ NewsThe Guardianrelated story and follow upBBC News OnlineNew Daily.

Better masks eliminate risk

The quality of respiratory masks healthcare workers wear makes a huge difference to their risk of coronavirus infection, Cambridge University Hospitals NHS Foundation Trust research has found. Providing staff high grade FFP3 respirators, a long-time demand of UK unions, can result in up to 100 per cent protection.

By contrast, there is a far greater chance of staff wearing standard issue surgical masks catching the virus. For most of last year, the hospital followed national guidance which specifies that healthcare workers should wear surgical masks, except in a few limited situations. Though fluid resistant, these masks are relatively flimsy and loose-fitting and are not meant to screen out infectious aerosols - tiny virus particles that can linger in the air and are now widely accepted as a source of coronavirus infection.

The study found that staff caring for COVID patients on “red” wards faced a risk that was up to 47 times higher than those on “green” or non-COVID wards. Lead researcher Dr Mark Ferris, a specialist in occupational health at the hospital, said staff were getting COVID despite doing everything they were asked to in terms of infection control.

When the second wave of the pandemic began in the UK last December, managers made a local decision to upgrade the protection on red wards. “The only thing left to try that could make a difference was FFP3 respirators, and they did,” Dr Ferris said. In the weeks following this move, the rate of infections among healthcare workers on red wards dropped spectacularly, quickly falling to the level experienced by staff on green wards where there were no COVID patients. The study concludes that “cases attributed to ward-based exposure fell significantly, with FFP3 respirators providing 31-100 per cent protection (and most likely 100 per cent) against infection from patients with COVID-19.” The paper says fluid-resistant surgical masks were “insufficient” to protect healthcare workers. Read more: Mark Ferris, et al. FFP3 respirators protect healthcare workers against infection with SARS-CoV-2, Authorea. 24 June 2021 [pre-print]. DOI: 10.22541/au.162454911.17263721/v1. BBC News Online. Source: Risks 1003

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