Originally Posted by
corporate-wage-slave
You may want to cast your eye on this piece of research via St. Andrews University (22 step thread, you have to click through):
https://twitter.com/mugecevik/status...92347010215947
Dr. Cevik's analysis essentially shows that
generally speaking two thirds to three quarters of infections come via symptomatic patients spreading the disease to their partner, to their family and in health care settings. Casual contact, contact via door handles, supernarket squeeze passing, joggers - particularly if outdoors, particularly with asymptomatic cases - doesn't cause infection on any scale. Unforutnately our lockdown doesn't greatly help with those cases that are happening and it's not easy to resolve..
RIght now, in the UK, the majority of cases are heath care settings, if we include care homes. In other words community infection in the community is now very low., particularly in London
When you have approximately 7,000 a day landing at Heathrow, even if 1% are symptomatic, way over a plausible level, having self solation as an added restriction makes no sense since 70 x R is statistically unmeasureable when N = 66 million. Dr. Cervik puts transport related infections at around 11%, so aviation would be tiny. But this is in a context when arriving travellers and the public are both suposed to be mainly staying at home and greatly reducing personal contact.
Going forward, imagine a situation - for example early June - when the lockdown could be reduced, there won't be a presumption of staying at home, working from home, the context therefore changes and lockdown won't be the norm. Therefore with a low level of community infection as a baseline, even 70 x R becomes an issue and hence the suggestion that arriving passengers are treated differently. Or rather these passengers would continue to do what they are supposed to be doing now.
I hope this makes the logic clearer.
As ever, thanks C-W-S for the insights and some commentary.
To me, the logic falls the moment the start point seems to be symptomatic cases. Well, if there are symptomatic cases arriving at Heathrow then it goes without saying they can't and mustn't enter the community. So if Heathrow (or any port of entry) isn't geared up to identify / help / safely handle symptomatic cases then that is a huge problem and needs dealing with as a basic pre-step.
The trickier issue, surely, is the pre-symptomatic and asymptomatic cases. By definition, these are harder to pick out (just as they are in the wider community!!).
How is that risk assessed for total expected arrivals (is the potential number of carriers AND their future actions too much?) and then managed? and reduced to an achievable non-NIL level. A starting point for that approach might be to not allow flights from origins with high Covid-19 caseloads &/or poor data &/or sub-par pre-flight screening.
What I don't currently see is the logic of the response aligning to the actual risk(s) to the wider UK population.
Standing back, as I've mentioned in other threads, it is the actions of the individuals in the post lockdown community which keeps the R <1.
I'm not so sure the 'traveller individual' is inherently less able to practice good Covid-19 hygiene, mask wearing, social distancing, self-diagnosis, in the community, than the average citizen.