VERY SOBERING - Modeling outcomes and social distancing (MASS Testing is the only answer)

[Roland99]

Trevor Bedford
@trvrb
Scientist
@fredhutch
, studying viruses, evolution and immunity.
Seattle, WAbedford.ioJoined December 2010
663 Following
147.2K Followers

Link to tweet

Trevor Bedford
@trvrb
I've been mulling over the
@MRC_Outbreak
modeling report on #COVID19 mitigation and suppression strategies since it was posted on March 16. Although mitigation through social distancing may not solve things I believe we can bring this epidemic under control. 1/19

https://threadreaderapp.com/thread/1240444821593944064.html

I've been mulling over the @MRC_Outbreak modeling report on #COVID19 mitigation and suppression strategies since it was posted on March 16. Although mitigation through social distancing may not solve things I believe we can bring this epidemic under control. 1/19

But first, the report. @neil_ferguson, @azraghani and colleagues model COVID-19 epidemic outcomes under different intensities of non-pharmaceutical, aka social distancing, interventions. 2/19

MRC Centre for Global Infectious Disease Analysis
@MRC_Outbreak
UPDATE: #Coronavirus

➡more intensive interventions now needed in UK to slow down #COVID19 spread, reduce pressure on healthcare & protect those most at risk
➡️careful monitoring required when interventions relaxed

🔰Full report: https://www.imperial.ac.uk/mrc-global-infectious-disease-analysis/news--wuhan-coronavirus/

Different mitigation scenarios that include things like school closures, isolation of symptomatic individuals and quarantine of exposed household members, result in #flatteningthecurve and reducing mortality, but under the author's assumptions still result in an epidemic. 3/19

Given assumed severity of COVID-19 infections, this flattened epidemic is still severe, resulting in over 1 million deaths in the US and >250k deaths in GB, mostly concentrated in those over 60 and with underlying health conditions. 4/19

Alternatively, with stronger social distancing, the epidemic could be brought under control and effectively "suppressed". However, stopping this level of social distancing would result in a fairly rapid rebound as the population would still lack immunity to the virus. 5/19

Managing this level of social distancing required for suppression while still having a functional economy and society would be difficult and it's not at all clear that this could be maintained for the ~18 months until we have a vaccine. 6/19

This is the catch-22 as presented by the report. 7/19
However, I'm not quite that pessimistic. Although I agree that basic mitigation efforts won't stop the epidemic, I have hope that we can solve this thing by doing traditional shoe leather epidemiology of case finding and isolation, but at scale, using modern technology. 8/19

There are two main case-based strategies that I see here, both related, as well as a supporting serological strategy. 9/19

The first strategy revolves around a massive rollout of testing capacity. We believe that a significant proportion of epidemic transmission is due to mild and maybe even asymptomatic infections (science.sciencemag.org/content/early/…). 10/19

We also believe that a significant amount of transmission may occur in the window before symptoms develop (evidence from viral load dynamics
SARS-CoV-2 Viral Load in Upper Respiratory Specimens of Infected Patients | NEJM
Correspondence from The New England Journal of Medicine — SARS-CoV-2 Viral Load in Upper Respiratory Specimens of Infected Patients
https://www.nejm.org/doi/full/10.1056/NEJMc2001737
, evidence from serial intervals ncbi.nlm.nih.gov/pubmed/32145466). 11/19

These transmission routes can be reduced by a huge rollout of testing capacity. If someone can be tested early in their illness before they show symptoms, they could effectively self isolate and reduce onward transmission compared to isolation when symptoms develop. 12/19

This strategy of massive testing has been a cornerstone in South Korea's response (
Coronavirus cases have dropped sharply in South Korea. What’s the secret to its success?
A scary brush with Middle East respiratory syndrome led the country to set up the world’s most expansive testing program for COVID-19
https://www.sciencemag.org/news/2020/03/coronavirus-cases-have-dropped-sharply-south-korea-whats-secret-its-success

) and we're now seeing their epidemic brought under control without the stringent policies put in place elsewhere. Case counts in South Korea via @covid2019app. 13/19

This rollout of testing could be achieved through at home delivery of swabs with centralized lab-based processing combined with drive-through testing facilities. There are logistics involved in getting a result quickly, but it's really just logistics, which can be solved. 14/19

The second, related, strategy is using cell phone location data combined with data on known positive cases to alert possible exposures to self isolate and get tested. Figure from @ChristoPhraser and colleagues who've considered this in detail. 15/19

This strategy targets testing capacity at most likely cases and serves to detect exposure events early, when isolation is most valuable. This cell phone location based approach is outlined carefully here:
BDI-pathogens/covid-19_instant_tracing
Quantifying dynamics of SARS-CoV-2 transmission suggests that epidemic control and avoidance is feasible through instantaneous digital contact tracing - BDI-pathogens/covid-19_instant_tracing
https://github.com/BDI-pathogens/covid-19_instant_tracing
. 16/19

A third, supporting, strategy: as the epidemic proceeds get serological assays run on as many people as possible to systematically identify individuals who have recovered and are highly likely to possess immunity. 17/19

Individuals who have serological evidence of recovery and are no longer shedding virus can fully return to the workforce and keep society functioning (especially important for those at the clinical front lines). 18/19

Together, I believe these (and other case-based) strategies can bring down the epidemic. This is the Apollo program of our times. Let's get to it. 19/19

His premise of the best mitigation is all based upon massive and widespread testing at very early stages to identify and isolate the infected as quickly as possible

We’ve seen this administration drop the ball for two months and running, tho, so I’m nkt holding my breath

This is a societal game-changer. This will change human behavior for quite some time

The time for The Great Pause (lockdown/shutdown the world - at least the US to be selfish) has passed I fear.

[canetoad]

1. The answer is testing

Then isolating.

[uponit7771]

2. OK, somethings up. These people are willing to crash whole economies instead of test & isolate?

[bluedigger]

3. They began implementing this strategy in San Miguel County, CO yesterday.

Telluride will be our test case. 👍

[Roland99]

4. Oh that's good news!

I’ve heard of drive up tests in and around central FL but people with some or even most of the symptoms are still being turned away