Wow. Only now getting to read this #covid19 paper at the end of a busy day. But what a read. It Spells out the issues very clearly. Quick thread.
It starts with two basic strategies:
1. Suppression: Try to keep #SARSCov2 from spreading. Interrupt transmission and bring number of new cases all the way down. That’s what China did.
2. Mitigation: Accept that spread is inevitable, but try to slow it down and reduce impact.
1. Suppression: Try to keep #SARSCov2 from spreading. Interrupt transmission and bring number of new cases all the way down. That’s what China did.
2. Mitigation: Accept that spread is inevitable, but try to slow it down and reduce impact.
"In this report, we consider the feasibility and implications of both strategies for #COVID19, looking at a range of NPI measures”.
‘NPI’ = non-pharmaceutical interventions. Since we don’t have a vaccine or drugs, that is all we have for now: quarantines, social distancing, etc.
‘NPI’ = non-pharmaceutical interventions. Since we don’t have a vaccine or drugs, that is all we have for now: quarantines, social distancing, etc.
Choice between 1 and 2 is terrible, as authors note: "Suppression, while successful to date in China and South Korea, carries with it enormous social and economic costs which may themselves have significant impact on health and well-being in the short and longer-term."
"Mitigation will never be able to completely protect those at risk from severe disease or death and the resulting mortality may therefore still be high.” Only advantage: Population slowly builds up immunity, which may eventually stop epidemic.
So the authors went ahead and simulated these two scenarios. A lot of assumptions about transmission and disease progression etc. that are obviously important, but it’s late and I’ll stick to results here for now. (Details in the paper.)
What happens if nothing is done: “We predict 81% of the GB and US populations would be infected over the course of the epidemic.” Peak in deaths after 3 months. “In total, in an unmitigated epidemic, we would predict approximately 510,000 deaths in GB and 2.2 million in the US."
"For an uncontrolled epidemic, we predict critical care bed capacity would be exceeded as early as the second week in April, with an eventual peak in ICU or critical care bed demand that is over 30 times greater than the maximum supply in both countries"
Please remember this is a model! And specifically one looking at what would happen, if we did nothing to stop #covid19.
So what about the two strategies. Well, basically, the report says, mitigation will not work. Even in the most optimistic scenario surge limits for beds in both general wards and ICUs would be exceeded at least 8-fold.
What’s worse: "even if all patients were able to be treated, we predict there would still be in the order of 250,000 deaths in GB, and 1.1-1.2 million in the US” And this is basically with the strategy the UK government seemed to be advocating last week.
So what happened? "In the UK, this conclusion has only been reached in the last few days, with the refinement of estimates of likely ICU demand due to COVID-19 based on experience in Italy and the UK” and with NHS providing more certainty about their hospital surge capacity.
So all that is left then is suppression: "We therefore conclude that epidemic suppression is the only viable strategy at the current time.”
"The social and economic effects of the measures which are needed to achieve this policy goal will be profound. Many countries have adopted such measures already, but even those countries at an earlier stage of their epidemic (such as the UK) will need to do so imminently."
This is a crucial point. If the strategy was mitigation the idea would be to target interventions in a time window around the peak of the epidemic. That seems to have been the rationale in the UK for waiting with some measures.
But: "For suppression, early action is important, and interventions need to be in place well before healthcare capacity is overwhelmed.” So we are basically back to plan A: throw the kitchen sink at this #covid19 epidemic. And do it now.
And suppression not only needs to start early, it needs to keep going for a long time: "To avoid a rebound in transmission, these policies will need to be maintained until large stocks of vaccine are available to immunise the population – which could be 18 months or more.”
As the authors emphasise: It "is not at all certain that suppression will succeed long term; no public health intervention with such disruptive effects on society has been previously attempted for such a long duration of time.” That’s at the end of the paper.
So that’s where we are at, according to this ONE modelling study: Massive interventions need to be done right now and may have to be maintained for more than a year (maybe with short periods of them being lifted in between, a kind of collective drug holiday).
It’s important to point out the caveats and there are many: There’s a lot of assumptions built into the model that may be wrong. The virus could change, drugs could become available, seasonality may still end up playing a role. And then there is us, the humans.
I left out the last sentence of the paper. After saying that this has never been attempted, the authors write: "How populations and societies will respond remains unclear.” Yes, it is unclear. And crucial. It is - ultimately - up to us.
