Risk is Indoors, Not Outdoors
It’s becoming increasingly apparent that most if not all of the spread happens inside buildings. There have been ‘superspreader’ events in churches, auditoria and elsewhere and a recent paper out of China looking at 318 outbreaks across 120 cities involving over 7,000 cases found all identified outbreaks involving three or more cases occurred in an indoor environment.
That paper awaits peer review but it’s certainly not alone in suggesting sharing indoor space is a major contributor to infection risk: another paper out of Japan showed the chance of a primary case transmitting COVID-19 in a closed environment was nearly twenty times greater than in the open air.
One of the most interesting findings is from the CDC in South Korea – who are held in high regard given the way the outbreak was managed there. They recently investigated an outbreak in a call centre in Seoul and tested 1,143 people. They found 97 confirmed cases and of these 94 were working in an 11th-floor call centre. The blue colour shows where confirmed cases were sitting.
The paper makes interesting reading and shows the benefits of extensive contact tracing and testing – but for me, the really interesting aspect is it suggests the virus does not spread so easily via fomites (surfaces).
Were it spreading via high-touch surfaces, more people in that building would have been sickened by touching lift buttons, door handles etc. The outbreak was almost entirely limited to one call centre in one part of one floor where staff were in close proximity. It didn’t spread via high-touch surfaces or in lobbies, washrooms etc.
These are not the only examples. Careful contact tracing has shown there have been outbreaks originating in restaurants and many from religious events of all flavours – there have been examples in Korea, Israel, Iran, plus it seems communal singing is a culprit. There have been a number of choirs where it spread like wildfire with very high attack rates.
There are now sufficient studies showing this really is a droplet-borne ‘social’ virus that the US CDC changed its advice yesterday.
What does this mean for our social and working lives? It’s apparent physical distancing won’t be enough, especially indoors; it’s droplet control too.
The 3Cs Model
While it’s very difficult to compare countries as there are so many confounding factors the Japanese model or “Three Cs” (when translated from mitsu no mitsu) is interesting. The advice is to avoid closed spaces with poor ventilation, crowded places with many people nearby and close-contact settings such as close-range conversations.
But in Japan mask-wearing is far more widespread anyway and behaviours like shaking hands, embracing and other forms of physical contact are not part of traditional Japanese greetings. Also conversing on crowded commuter trains is considered poor etiquette – and using a mobile is even worse. These behaviours all help limit the possibility of droplet transmission; as I say comparisons are difficult but the 3Cs message fits in well with the emerging data.
AVOID CLOSED SPACES WITH POOR VENTILATION
AVOID PLACES CROWDED WITH MANY PEOPLE
AVOID CLOSE CONTACT SUCH AS CLOSE-RANGE CONVERSATIONS
I really can’t see a return to large-scale sports events, concerts or religious events anytime soon. At least not in countries that place the importance of public safety higher than that of collective acts of religious observance (be they of the sporting or god-bothering variety).
Here in the UK it’s been suggested almost twice as many people visit the theatre every year in London as watch Premier League football but I’m not hopeful for either. At least football matches could be played to empty stadia if the economics are viable – but the same really can’t be said of theatres. Ditto the 170 million cinema visits per year.
While considering the arts (rare for a philistine like me) I think it’s brighter for film and TV production though, pretty much all of which bar news is currently suspended and desperate to get back to work. And everyone on lockdown is relying on them for new content! Yes, these are complex workplaces but they are still workplaces. And in workplaces risks can be (and are required to be) assessed and managed.
This is an industry where every activity is risk-assessed, so this is another one to add to the list – but very much in the light of current data. It’s probably critical they take really good advice from experts in infection control rather than just Health and Safety too; I can’t think of many industries where you might be spending millions on a drama shoot and if the talent gets sick you’re finished. Will it require changes to the way things happen? Of course it will, especially if you need to produce content at anything like the same pace as before.
This is a good example of needing to understand where the risks actually are rather than guessing and for that you need microbiologists or infection control experts. H&S people are lovely but I’ve seen many examples recently of non-experts take ‘model’ procedures from elsewhere and try to turn them into a workplace policy. It’s seldom pretty.
Returning to Work
I’m parking issues of mental health, legal and safety requirements for employers – I’m a microbiologist, remember?
For businesses contemplating bringing staff back from remote working or furlough, the modelling above makes it clear it’s not so much common touchpoints, it’s common airspaces that presents the principal risk. I’m not suggesting we give up sanitising touchpoints – far from it – but workplaces need to recognise the level of risk now associated with people talking for hours in close proximity – often with inadequate ventilation.
- At work it’s not so much about social distancing, it’s about physical barriers – screens and cubicles – rather than open offices and the 3Cs. Masks alone won’t cut it (see later).
- Meetings will need to be the exception – and if they are absolutely necessary they need to be shorter and smaller.
- Strategies for cohorting / separating teams could help.
- Visibly sanitising touchpoints etc might not be the most critical intervention in the light of the above data – but make staff feel safer which is very important.
But if you get the airflow/ventilation part wrong, people will get sick no matter how often you wipe the door handles. It’s all in the data…
Care is required, though – when considering ventilation note that in the restaurant example earlier overenthusiastic aircon above one table blew respiratory droplets across multiple diners.
In some regards, the advice remains the same. Distancing, not touching your face, and washing / sanitising your hands are the key interventions at an individual level. Wearing gloves is not helpful; the virus does not get in through the skin and may increase your risk because you likely won’t wash or sanitise your hands when they are on plus you’ll be touching stuff.
But at an organisational level, it’s much more about managing air spaces and ventilation.
Overall, what this means is we all need to accept some level of risk – but that’s an individual as well as a collective decision. Someone who is aged and with poor lung health will likely make very different choices to someone who’s younger and otherwise healthy.
Irrespective of any future containment/lockdown strategy this is not going away any time soon.
We’re talking years, not months – so shutting down the economy, education and everything else until it goes away really isn’t an option. Because it’s not going away.
We have to learn to live with it and do whatever we can to mitigate risk. But individuals and organisations need to properly understand the risk or they can’t manage it.
Again, in a workplace social distancing in the sense most people understand it will not offer the protection you think it does. Anway, to sum up:
SARS-CoV-2 is highly contagious – but it’s not as contagious as measles, mumps, or even some flu strains.
It is spread by respiratory droplets and aerosols, not food or brief, incidental contact – so social distancing, trying not to touch our faces and good hand and respiratory hygiene are key to reducing the spread.
While food and brief or outdoors contact are very low risk and can be helped with socially distancing, close proximity in confined spaces especially for longer periods presents a far greater risk.
COVID-19 is more deadly than flu (5-10-fold) but nothing like as deadly as a viral haemorrhagic fever like Ebola and it is worse the older you are. It’s dangerous, but the vast majority of people who get it survive it. It seems 10-15% might get very ill but that’s a difficult one to properly assess until we have a handle on how many people have already had it. If anyone tells you it’s just / not as bad as / no worse than flu, they don’t understand this organism.
Where's the Risk?
If you’re outside and you walk past someone, even if they have it for any likelihood of picking it up you’d likely need to be in close proximity for a number of minutes for any chance of an infection to spread. While joggers or cyclists may be releasing more virus due to deeper breathing, the exposure time is tiny as they zoom past. Yes, maintain a distance but don’t get paranoid; the risk is vanishingly small.
If you’re in a large supermarket or shopping mall you need to consider the volume of the space (large?), the number of other people (most likely restricted?), how long you’re spending there (half an hour?) and if you’re in a well-ventilated, large space with not too many people, the risk is low.
But if you’re working there the risk is higher – the extended time provides a greater chance of getting an infectious dose – risk = amount of virus exposure x exposure time, remember? Also in such environments staff are likely seeing many customers / others so the risk is higher. It’s a numbers game.
Basically you need to look at each environment you’re going to be in and make judgements. How many people? How much ventilation? How long will you be there? If you’re in an open office the assessment is more critical (volume of the space, people, and ventilation) – and if people are talking face-to-face the risk increases.
But most of all, your best strategy for mitigating risk is to listen to expert advice. And that advice WILL change as we discover more. Listen to infectious disease experts and reputable sources. And remember that reputable sources and proper scientists do not publish ‘research’ exclusively via YouTube videos.
Most of all, don’t listen to a science-denying serial lair who bribed a porn star in a conspiracy to conceal an affair they conducted while his third wife was giving birth to his child when he tells you how important it is for churches to reopen so YOU can all pray more.
Masks Post Script
Just a final word on masks – which also deserve a whole post. There are many types of mask, many ways of measuring effectiveness and many conflicting studies. If you have a particular bias or preconception about whether to use a particular type of mask in a particular situation you will be able to find a study that supports your hunch quite easily – as well as an equal and opposite study showing your bias is wrong.
You could be forgiven for thinking the potential benefits of mask wearing are so face-palmingly obvious, the simple fact they have not been made mandatory is proof positive of Government incompetence. But this is biology. It’s complicated. Sorry. I know everyone wants it all to be simple but it’s not.
The evidence and utility in healthcare settings where N95 or similar masks are being used by people trained to wear them properly and not touch their faces, or by people actively shedding virus is a very different proposition to wearing a mask on public transport or in an office.
While I’ve not been a fan of people who aren’t showing symptoms wearing masks (especially the types of mask needed by healthcare workers that have been in short supply) my view is evolving. But slowly.
There was a recent paper in Nature about surgical (as opposed to N95) masks that said:
“surgical face masks could prevent transmission of human coronaviruses and influenza viruses from symptomatic individuals”
The results weren’t stellar (like most studies into this) hence the pretty wishy-washy conclusion. Most studies show masks may be of some benefit in terms of preventing wearers both spreading or receiving the virus – but the data says the benefit is likely to be very modest. They offer nothing near ‘full’ protection – far from it.
The biggest factor in terms of non-medical use of face masks is how people actually use them. The studies show that the modest decrease in risk of spread is only there if people use their masks consistently and properly. When they don’t, what little protection there is vanishes.
And most people don’t use masks properly: they don’t fit them correctly, they keep adjusting and touching them and there’s now good data showing the extent of virus deposition on the outside of face masks, so if you have it touching your mask is a really good way to spread it. There’s also the false sense of security issue (just as there is with gloves) – people may well not be as rigorous with social distancing when wearing a mask just as people get lax with hand hygiene when wearing gloves.
So don’t overestimate the benefits and stick to the stuff (like hand and respiratory hygiene) that’s proven to work. If you absolutely have to wear one make sure you’ve had training so it actually protects you and others. I’m still trying to get my head around what this will look like for mass transit when capacity returns. Leave that with me for now…