Combating COVID-19 (SARS-CoV2)

00:01 So, how do we combat COVID-19 now? Given that the vaccine is experiencing its early days of penetration, and will not give us herd immunity for several months? Well, we have lockdown, mitigation, and therapeutic approaches.

00:17 The therapeutic approaches are things like dexamethasone.

00:20 For those individuals who are having breathing issues.

00:24 For a while we have the drug remdesivir, which showed some promise, but that is questionable now.

00:31 But mitigation tools like mask wearing are useful.

00:36 Lockdown is the most extreme societal tool we have.

00:42 But it does work.

00:44 The problem is public buy in is poor and it does result in economic hardship.

00:50 With the idea of a lockdown is as a disincentive for human behavior.

00:55 All it does is remove the opportunity for people to interact.

00:59 If you can't interact, you cannot transmit the disease.

01:03 Distancing is an important tool.

01:06 If we haven't got lockdown, then it's important for people to voluntarily restrict contact by keeping two meters away from each other, around there.

01:17 There's nothing magical about the two meter distance.

01:20 It's based on some studies done with influenza, suggesting that droplets tend to fall to the ground within two meters.

01:28 If you're not sneezing, or coughing, or otherwise projecting those droplets.

01:33 Mask wearing is important at the population level.

01:36 Masks are not meant to protect the wearer, although it does offer some protection for the wearer.

01:44 Most cloth masks are meant to be windbreaks, to prevent the breath from going more than a few centimeters beyond the mouth.

01:54 So this allows you to shorten the distance.

01:58 From those two meters, I mentioned to something less if someone's walking by you or you have to interact with an individual because of droplet cannot go as far.

02:06 Hand washing was thought early on to be an important tool because of suspicion of fomites transmission.

02:13 However, fomite transmission does not seem to be as big of a thing with COVID, as we had originally expected.

02:20 But hand washing still a useful tool to minimize viral transmission in general.

02:27 And of course, we have the vaccine as well, which is being rolled out around the world.

02:33 An important concept was brought to the fore back in March.

02:39 And this is how to think about the policy interventions and their consequences.

02:44 So, if you look at this curve here, the blue curve shows us, what would have happened if we had done nothing? The number of cases of coronavirus infection would have exploded quickly.

02:57 A vast percentage of people in your population who would have been infected very early on, and a large proportion of those would have been to the hospital and died.

03:06 And the healthcare system would have been overwhelmed.

03:09 It would have been chaotic, and would have threatened the fabric of society itself.

03:15 Instead, we pursued other tools.

03:17 A mitigation strategy, within to do's things like distancing, mask wearing, maybe some scheduling changes at work, minimize individual contact.

03:29 But a mitigation strategy delays the full infection of the population.

03:36 Maybe that's good enough, because you can control the flow of individuals through the hospital system with the expectation that they recover, but the system never gets overwhelmed.

03:47 The problem of course is that, a percentage of those who are infected are still going to die because the expectation here is that the majority of individuals will be infected.

03:58 So mitigation is not an ideal response, to my mind.

04:05 Then there is the suppression strategy, which involves aggressive social interventions, like social distancing, lockdowns, mask wearing, limits on gatherings, closing key industries like restaurants, possibly even schools.

04:26 This is a difficult thing for many countries to do particularly poor countries because it renders people quickly into unemployment and suffering.

04:34 So the economic cost is high, the psychological cost is high.

04:38 Some people call this, The Hammer.

04:40 You hammer the case load down quickly, so that you can dance.

04:47 What is the dance? As the hammer forces the incidence rate down very low, you can reopen parts of your society slowly and with care.

04:59 But as soon as human interaction increases, transmission increases.

05:03 But when transmission gets beyond a certain point, you reintroduce other restrictions and drive it down again, and repeat that process.

05:11 Dance. Let it go up, let it go down.

05:14 This buys us time to allow the vaccine to be developed and deployed to achieve herd immunity.

05:24 With that in mind, here is a plan of action put forth in early 2020, for dealing with the epidemic in the USA.

05:36 The first wave would have diminished at the end of June.

05:41 The cases peaked in mid April.

05:44 Antiviral trials had begun with mid April.

05:48 Testing capacity was high at the end of April.

05:51 Testing capacity got really high as the first wave was ending.

05:55 And this serology test became widely available in June.

06:00 The expectation that hospitals would surge their capacity, and everybody would return to work in June because the first wave would be over.

06:08 This was the expectation as the hammer did his job.

06:13 Public health could then gather its forces build infrastructure.

06:18 People get back to work. Schools could start to reopen.

06:24 The vaccine could start to be rolled out by the end of the summer and early fall.

06:32 The second wave could be suppressed in large degree.

06:36 Your captain check wouldn't be too out of control.

06:39 And the vaccine could finally start to be distributed in early 2021.

06:43 This was the plan.

06:44 But as a colleague of mine says, "If you pursue the hammer in the dance, you can only dance if you know the steps." So, the USA misstepped as in many countries, and this is not what unrolled in that country or others.

07:02 Instead, we have blobs of rolling cases.

07:08 A confused, confounded, jagged set of curves.

07:13 And now we await the vaccine to grant us herd immunity.