Life loss expectation due to COVID-19.

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Let's say 1,200 people have COVID in London today (I'd say that's about right). Based on current confirmation figures, ~300 more people will catch it tomorrow. There's ~6,000,000 people in the London NHS statistical area. Assume everyone is currently still living normally, which is almost right. Let's also say 40% of contractions occur within the home, 30% in workplaces, and 30% other places like the Tube/cafes/concerts etc (a guess but plausible). So tomorrow your risk of catching it in non-home non-office locations living normally is: (300 * 0.3) / 6,000,000 = 1 in 60,000. Assume also that getting infected costs 40 days of life, including direct illness + risk of death + risk of ongoing complications (this is a very uncertain but plausible number for a typical 30-yo). Then over the whole day of exposure in public places you're accruing: (40*24*60)/60,000 = 1 minute of life loss. That's not much at all and wouldn't be worth doing much about. (We should probably also halve that figure because even if you avoid it that time, there's a ~50/50 chance you'll get it later anyway.) How will things change over time? It will roughly double each week — faster to start, then slower over time. If that's right, if we were all to continue going about our normal business unchanged, in a month's time our public-place exposure risk alone would be shortening your life by 16 minutes a day. Not a huge deal, but maybe worth taking some actions based on. Is it unrealistic for doubling to continue over a month? Not really, by that time only 20,000 people in London would have it, or 1 in 300. So let's push forward a bit further. Two weeks later 1 in 75 people would have it (plausible), and each day of normal public behaviour would be costing you an hour of life expectancy. At that point it's likely sensible from a personal point of view to avoid normal public behaviour unless there's a really strong reason (e.g. you work stocking supermarkets and so getting to work on the Tube is essential to society). Keep in mind this is for a low risk group. The figures for a 75 yo would be something like 5-10x this, so they should start taking equivalently serious actions ~3 weeks earlier. Beyond that point it doesn't seem worth pushing the 'no response' hypothetical further as the idea that 1 in 75 have COVID in London and we aren't taking extremely serious actions is getting silly. --- The main problem with this analysis is it's missing population-level effects, which are the dominant issue right now. Arguably the time to come in with intense containment measures has already passed. And if not, the optimum moment is coming up very soon. The reason for this is not that we are each losing a minute of healthy life from commuting on the Tube and visiting the supermarket. It's because the date we begin enforcing containment measures like shuttering cafes and restaurants shifts the shape and peak of the 'flatten the curve' shape, or could even keep the containment phase running indefinitely until we have drugs/vaccines. It's very hard to do the math to go from the shape to the ultimate number of deaths, but a proper and strongly enforced response could ensure only 0.2% of the population dies in this pandemic rather than 1% in a scenario where we cock it up. From this perspective, using the above calculations to wait 1 month to stop eating out is super defecting on society. So much so that we won't be allowed to because they'll likely be asked to close before then.
Originally posted here: https://steemit.com/coronavirus/@meepins/life-loss-expectation-due-to-covid-19