الجمعة، 10 أبريل 2020

After Bending the Curve: Unwinding the Great Lockdown

Coronavirus particles (orange) emerging from a cell in culture.

As optimism grows that many areas around the world, including much of the US, are successfully “bending the curve” of the spread of COVID-19, there’s reason to hope the worst of the current wave of infections is nearly behind us. However, there hasn’t been much discussion of what it will take to safely walk back from the harsh stay-at-home, essential-businesses-only rules that have shut down a large piece of the global economy. There isn’t any agreed-on answer, at least not yet. But a successful long-term strategy needs to include a number of elements.

Tracing Will be Essential to Avoiding Another Wave

Countries that got on top of the pandemic early were in some cases able to effectively screen everyone entering their country, test everyone who was suspected of having the virus, and trace their contacts. In the US, we were late to the party and lacked nearly the testing infrastructure needed, so we jumped right to a mitigation approach. Any successful unwinding of our lockdown will require that we don’t have that problem again. However, the tracing tools credited with success in several Asian countries cross a lot of right-to-privacy lines that make them problematic for the US and many European countries. Fortunately, several teams of software researchers are working on solutions that do a much better job of preserving personal privacy.

Sample screenshot of the Covid Watch appOne of the most secure is Stanford-based Covid Watch, which is developing a Bluetooth-based system that uses a clever technique of creating unique IDs for each proximity event. When someone tests positive, their IDs can be broadcast to other users who can see if they were involved in any of the contacts. With this solution, the sponsoring organization never has any usable location data. Users will likely value that feature, but public health organizations will likely opt for having additional data if they get a choice.

Along that line, MIT’s powerhouse Media Lab team is working on a system that includes GPS, so it includes location data, but the data is stored by geographic area and hashed. This way, a user can ask for the compiled hashed data showing possible contacts with an infected person for any of the areas they have visited. The app will then be able to hash the user’s own data and see if there are matches. This doesn’t completely protect location data, but it certainly does a good job of obscuring it.

A major issue with all these solutions and others being worked on is that proximity isn’t accurate as a measure of exposure. If you are on the opposite of a wall or facing away from someone, for example, you have much less chance of infection than if you are speaking with them face to face. It will be interesting to see if someone can combine the sensors available on modern smartphones to create a more accurate metric for how dangerous a possible contact might have been.

Tracing Only Works With Testing

Tracing is a great source of raw material for knowing who to test. But for it to work at scale, we’ll need to have mass access to inexpensive, fast tests. They’ve been slow in coming, but 15-minute tests like the one produced by Abbott show that it is completely doable. Abbott’s quick turnaround on getting the test to market is possible because they have leveraged their existing, office-friendly, ID NOW platform that is already used to test for flu and other viruses.

Abbott Labs while-you-wait virus test device

Abbott Labs’ while-you-wait virus test device is in wide use for flu tests. It’s being updated so it can also test for nCoV-2019, the virus that causes COVID-19.

In addition to the current diagnostic tests, we’ll also need to deploy antibody tests. This way, we can identify who has already had the disease and therefore would be a great candidate for doing jobs that involve a lot of potential exposure. Those people may also be a good source of antibody-rich plasma as part of a therapeutic regime. Stanford has launched an initial program that has tested 3,200 volunteers around the Bay Area to see how many have developed antibodies, in an effort to better estimate how the disease spreads and when the first — probably undiagnosed — cases occurred.

There is a growing consensus among the medical research community that what we need are inexpensive tests that can be administered at convenient locations such as pharmacies. But I hope we shoot a bit higher than that, in that we are able to design our testing infrastructure so that the next time there’s a new strain of virus, the infrastructure can be adapted much more quickly and easily than the massive, time-consuming effort we’ve gone through to adapt our existing tests.

Therapeutics

One of the scariest aspects of COVID-19 is that it is much more lethal than the flu. While no one likes getting the traditional seasonal flu, it only sends a small fraction of its victims to the hospital, let alone confine them to ventilators. Development and deployment of effective treatments will go a long way in easing the massive wave of fear COVID-19 has caused. To meet that need, we’ll have to have a treatment that goes far beyond the current “try everything even if there are only anecdotal reports of it working” and instead have proven, repeatable, positive results.

The good news is that there are quite a lot of promising avenues of research here, including repurposing existing antibiotics such as hydrocloroquine (which has gotten the most attention and the biggest government investment), adapting antiviral drugs, and searching our virtual medical cabinet for other existing drugs that might be useful and could be deployed quickly.

Convalescent plasma therapy — using donated plasma from survivors to help treat victims — has been used in previous similar outbreaks. Tests using that approach to treating COVID-19 patients has started, but it is too early to assess its effectiveness.

Highly Effective Vaccine

As Bill Gates and others have pointed out, life won’t really get back to normal until we have an effective vaccine. There is no question that we will have a vaccine, although not nearly as fast as anyone would like. But the quality of a vaccine is highly variable and will depend on its initial effectiveness and how fast the virus mutates. Some vaccines are highly effective, enough that combined with herd immunity we have essentially eliminated some diseases. Others, like the flu vaccine, have effectiveness closer to a 50/50 coin flip.

From this graphic you can see the chronology of how the virus spread around the world

From this Nextstrain.org graphic, you can see the chronology of how the 2019-nCoV virus that causes COVID-19 mutated as it spread around the world.

The reason we need a new flu vaccine each season is that the flu mutates quickly. Fortunately, so far the virus that causes COVID-19 mutates more slowly. But as the above image from Nextstrain.org shows, it changes rapidly enough that it’s likely whatever vaccine we develop will need to be updated and readministered periodically.

The Economy: Putting Humpty-Dumpty Back Together Again

Just like with the virus itself, estimates of how long it will take before our economy is fully functional again are all over the map. The details of that process are beyond the scope of this article. One thing is certain, though: No matter how much money we pour into the recovery, getting our medical act together in the form of testing, tracing, treatment, and an effective vaccine will be a necessary pre-condition to a true economic rebound.

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