Staying safe from coronavirus

Staying safe - community precautions

The good news is that "Non pharmaceutical interventions", in other words face coverings and physical distancing can bring ourbreaks under control.

A recent meta-study31142-9/fulltext) reports that transmission of viruses was lower with physical distancing of 1 metre or more, compared with a distance of less than 1 metre. Protection was increased as distance was lengthened (a non-linear effect, greater distancing gives much greater protection).

On 5th May this year, Patrick Vallance (Government Chief Scientific Adviser) himself said “The risk at 1 meter is about 10 to 30 times higher than at 2m.” In other words, coronavirus spread is up to 30 times higher when someone is 1m away from an infected person than 2m away.

Face-mask use can result in a large reduction in risk of infection, with stronger associations with N95 or similar respirators compared with disposable surgical masks or similar. Eye protection also was associated with less infection. Evidence for the efficacy of widescale mask wearing came in June 2020 from the German town of Jena. Cases of nfection in Austria dropped by 90 per cent following their introduction last April.

This visualisatio shows how masks help to protect others by loca;lisng the effect of coughs and sneezes.

Here's another one - "A picture is worth a thousand words".

The Lancet study31142-9/fulltext) suggests, with the absence of a vaccine, that reduction due to physical distancing is roughly 80% (each 3ft reduces by half) Crude masks give roughly 66% reduction, N95 (FFP3) or 12-16 layer cotton masks give around 85% reduction.

"From a policy and public health perspective, current policies of at least 1 m physical distancing seem to be strongly associated with a large protective effect, and distances of 2 m could be more effective. These data could also facilitate harmonisation of the definition of exposed (eg, within 2 metres), which has implications for contact tracing. The quantitative estimates provided here should inform disease-modelling studies, which are important for planning pandemic response efforts. Policy makers around the world should strive to promptly and adequately address equity implications for groups with currently limited access to face masks and eye protection."

There has been a surprising amount of resistance to wearing face masks in Western countries, aided and abetted by governments and scientists. From early in the pandemic we were wearing masks on the basis that it could prevent us from infecting others and it might reduce our exposure to the virus. The rationale for this is expressed clearly in this in The masks Masquerade", a critique of "the science" from Nassim Taleb.

More recent studies are showing the effectiveness of cloth face coverings in general, underlining our precutionary approach. A study from The University of California in San Fransisco, researchers contend that people wearing face coverings will take in fewer coronavirus particles. This initial "viral load" is seen as important in allowing our immune system to overcome an initial infection. The San Francisco study concludes that "Population-level masking shows the benefits of mask-wearing for the individual (as well as others) as a pillar of COVID-19 pandemic control"

In addition, the increase in face mask wearing in eastern coutries at the outbrak of the pandemic was associated with a [reduction in cases] (ref)of the usual winter 'flu.

As for plastic face shields, although providing some protection, he Swiss government has warned that they are inadequate and should only be worn in combination with a face mask.

Conclusion

A combination of face masks and social distancing will drastically reduce the chances of transmitting the disease, along with other respitory infections. Face shields are not as safe as well-fitting cloth face coverings.

Masks help to protect us, but more importantly they help to protect other people and slow transmission.

For those who see facemask wearing as an infringement of their civil liberties, please watch this short clip fromDan Levy

staying safe - testing

"Good comprehensive small area data with extensive testing plus early actions in the hot spots is the only way to both regain control and manage outbreaks. Local, shoe leather, epidemiology and interventions required." Dr Bharat Pankania

In the early days of the outbreak, a lot of faith was placed in antibody tests that were supposed to indicate who has had the disease, and so would be safe going back to work (or to class) and who would still be at risk from the virus. Again this virus has proved more challenging than we first thought. Antibody tests have shown surprisingly low resultsfrom around the world. (Prof John Wright BIHR)

We know the viral attack causes functional exhaustion and depletion of T-cells and that the antibodies some people produce are ineffective

Lack iof openness around testing in the UK

A sensitive test correctly identifies the presence of a virus. A high sensitivity gives a low number of "false negatives", where you have the disease but the test doesn't pick it up.

A specific test picks up only the virus in question, and not something else.A high specificty gives a low number of "false positives", where you don't have the disease but the test is picking up something else.

Conclusion

It is difficult to get hold of figures for all the tests that are out there. What we do know is that it is better to have large numbers of tests with an inaccurate method than a small number of very accurate ones. At this time, the number of daily tests within the UK is unlikely to provide us with particularly accurate information on what is going on.

What we know about the virus

The spread of SARS-CoV-2

Staying safe

What we still don't know about the virus

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