Report by Imperial College COVID-19 Response Team

2,297 Views | 10 Replies | Last: 6 yr ago by Gordo14
Pumpkinhead
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Is advising the UK's approach to this and per news reports also was given over the weekend to White House/CDC. Is a long, extremely detailed analysis of the situation and models out the different possible approaches to deal with this virus and models out the outcomes of each approach.

Their models concluded that if a 'do nothing' approach had been followed (no control measures put in place and no change in the population behavior) would have resulted in "510,000 deaths in the UK and 2.2 million deaths in the United States, not accounting for the potential negative effects of health systems being overwhelmed on mortality."

https://www.imperial.ac.uk/media/imperial-college/medicine/sph/ide/gida-fellowships/Imperial-College-COVID19-NPI-modelling-16-03-2020.pdf


Quote:

Two fundamental strategies are possible: (a) mitigation, which focuses on slowing but not necessarily stopping epidemic spread reducing peak healthcare demand while protecting those most at risk of severe disease from infection, and (b) suppression, which aims to reverse epidemic growth, reducing case numbers to low levels and maintaining that situation indefinitely. Each policy has major challenges. We find that that optimal mitigation policies (combining home isolation of suspect cases, home quarantine of those living in the same household as suspect cases, and social distancing of the elderly and others at most risk of severe disease) might reduce peak healthcare demand by 2/3 and deaths by half. However, the resulting mitigated epidemic would still likely result in hundreds of thousands of deaths and health systems (most notably intensive care units) being overwhelmed many times over. For countries able to achieve it, this leaves suppression as the preferred policy option.

Quote:

We show that in the UK and US context, suppression will minimally require a combination of social distancing of the entire population, home isolation of cases and household quarantine of their family members. This may need to be supplemented by school and university closures, though it should be recognised that such closures may have negative impacts on health systems due to increased absenteeism. The major challenge of suppression is that this type of intensive intervention package or something equivalently effective at reducing transmission will need to be maintained until a vaccine becomes available (potentially 18 months or more) given that we predict that transmission will quickly rebound if interventions are relaxed. We show that intermittent social distancing triggered by trends in disease surveillance may allow interventions to be relaxed temporarily in relative short time windows, but measures will need to be reintroduced if or when case numbers rebound. Last, while experience in China and now South Korea show that suppression is possible in the short term, it remains to be seen whether it is possible long-term, and whether the social and economic costs of the interventions adopted thus far can be reduced.

Quote:

Whilst our understanding of infectious diseases and their prevention is now very different compared to in 1918, most of the countries across the world face the same challenge today with COVID-19, a virus with comparable lethality to H1N1 influenza in 1918. Two fundamental strategies are possible2:

(a) Suppression. Here the aim is to reduce the reproduction number (the average number of secondary cases each case generates), R, to below 1 and hence to reduce case numbers to low levels or (as for SARS or Ebola) eliminate human-to-human transmission. The main challenge of this approach is that NPIs (and drugs, if available) need to be maintained at least intermittently - for as long as the virus is circulating in the human population, or until a vaccine becomes available. In the case of COVID-19, it will be at least a 12-18 months before a vaccine is available3. Furthermore, there is no guarantee that initial vaccines will have high efficacy.

(b) Mitigation. Here the aim is to use NPIs (and vaccines or drugs, if available) not to interrupt transmission completely, but to reduce the health impact of an epidemic, akin to the strategy adopted by some US cities in 1918, and by the world more generally in the 1957, 1968 and 2009 influenza pandemics. In the 2009 pandemic, for instance, early supplies of vaccine were targeted at individuals with pre-existing medical conditions which put them at risk of more severe disease4. In this scenario, population immunity builds up through the epidemic, leading to an eventual rapid decline in case numbers and transmission dropping to low levels.

The strategies differ in whether they aim to reduce the reproduction number, R, to below 1 (suppression) and thus cause case numbers to decline or to merely slow spread by reducing R, but not to below 1.

Quote:

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. Instead we focus on feasibility, with a specific focus on what the likely healthcare system impact of the two approaches would be. We present results for Great Britain (GB) and the United States (US), but they are equally applicable to most high-income countries.


Quote:

Results
In the (unlikely) absence of any control measures or spontaneous changes in individual behaviour, we would expect a peak in mortality (daily deaths) to occur after approximately 3 months (Figure 1A). In such scenarios, given an estimated R0 of 2.4, we predict 81% of the GB and US populations would be infected over the course of the epidemic. Epidemic timings are approximate given the limitations of surveillance data in both countries: The epidemic is predicted to be broader in the US than in GB and to peak slightly later. This is due to the larger geographic scale of the US, resulting in more distinct localised epidemics across states (Figure 1B) than seen across GB. The higher peak in mortality in GB is due to the smaller size of the country and its older population compared with the US. In total, in an unmitigated epidemic, we would predict approximately 510,000 deaths in GB and 2.2 million in the US, not accounting for the potential negative effects of health systems being overwhelmed on mortality.

hamean02
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Predicting 81% of us get this seems very very high.
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Yukon Cornelius
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Presser today the docs said this wasnt true.
Pumpkinhead
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AG
dp
Pumpkinhead
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Yukon Cornelius said:

Presser today the docs said this wasnt true.
Didn't see the presser, said they don't agree with the report, or that they didn't include it in their own analysis?

I'd be very interested as a citizen knowing what models/reports the CDC/WH were using to drive their decision making.
Yukon Cornelius
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AG
Pumpkinhead said:

Yukon Cornelius said:

Presser today the docs said this wasnt true.
Didn't see the presser, said they don't agree with the report, or that they didn't include it in their own analysis?

I'd be very interested as a citizen knowing what models/reports the CDC/WH were using to drive their decision making.
They didnt agree with the model saying its impossible to know and they think those numbers are too high.
Pumpkinhead
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AG
Yukon Cornelius said:

Pumpkinhead said:

Yukon Cornelius said:

Presser today the docs said this wasnt true.
Didn't see the presser, said they don't agree with the report, or that they didn't include it in their own analysis?

I'd be very interested as a citizen knowing what models/reports the CDC/WH were using to drive their decision making.
They didnt agree with the model saying its impossible to know and they think those numbers are too high.
Thanks.
HotardAg07
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Pumpkinhead said:

Yukon Cornelius said:

Presser today the docs said this wasnt true.
Didn't see the presser, said they don't agree with the report, or that they didn't include it in their own analysis?

I'd be very interested as a citizen knowing what models/reports the CDC/WH were using to drive their decision making.
NY Times reported that the model the CDC presented showed between 200,000 and 1.7MM Americans dying in varying scenarios.
https://www.nytimes.com/2020/03/13/us/coronavirus-deaths-estimate.html
Shaun Shaikh '07
HotardAg07
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Quote:

One of the agency's top disease modelers, Matthew Biggerstaff, presented the group on the phone call with four possible scenarios A, B, C and D based on characteristics of the virus, including estimates of how transmissible it is and the severity of the illness it can cause. The assumptions, reviewed by The New York Times, were shared with about 50 expert teams to model how the virus could tear through the population and what might stop it.

The C.D.C.'s scenarios were depicted in terms of percentages of the population. Translated into absolute numbers by independent experts using simple models of how viruses spread, the worst-case figures would be staggering if no actions were taken to slow transmission.

Between 160 million and 214 million people in the United States could be infected over the course of the epidemic, according to a projection that encompasses the range of the four scenarios. That could last months or even over a year, with infections concentrated in shorter periods, staggered across time in different communities, experts said. As many as 200,000 to 1.7 million people could die.
Shaun Shaikh '07
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Gordo14
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MyNameIsKyle said:

Lots of "could"s in that report.


Every model for a new virus that we don't fully understand is going to have "could"s in it. Does that mean we shouldn't model it? Surely blissful ignorance leads to better outcomes.
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