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Contact Tracing: How Does It Work?

 April 23, 2020 at 11:23 AM PDT

Speaker 1: 00:00 Debt was the top focus of governor Newsome's co-fund 19 update today with some relief for those people who have student debt and people who stimulus checks have been garnished by creditors. Newsome announced that a variety of student lenders have waived payments and fees for 90 days. And today he signed an executive order that stops banks and debt collectors from garnishing stimulus checks that the federal government has been sending out as part of the cares act. Speaker 2: 00:27 It's also retroactive. So if you're a debt collector and you did garnish, uh, those contributions, those checks, you gotta give them back. Uh, and so that is effective immediately. Speaker 1: 00:38 The governor also announced that Wednesday was the deadliest day from Corona virus in California. 115 people in the state died. That's an 8.5% increase in the number of deaths plus increases in the number of people who have tested positive. But there remains some stabilization in the curve of patients admitted to the ICU. And the governor is warning Californians to remember to practice social distancing and caution if they plan to get out of the house with a warm weather coming this weekend. But it's not only social distancing that will determine when we can get outdoors. Again, the process of lifting stay at home orders in California depends in large part on the state's ability to test for covert 19 and identify those who may have been exposed to the virus. The process of identification is conducted through contact tracing. Governor Newsome announced yesterday in his daily news update that the state wants to train 10,000 people to be contact tracers pulling some of those new tracers from the existing state workforce. In addition to that effort, governments are exploring the use of digital apps. To backtrack the movement of sick people and find out who they may have been in contact with. Joining me is Andrea LaCroix, professor of epidemiology at UC San Diego and professor LaCroix, welcome to the program. Speaker 3: 01:59 Thank you. Thanks for having me. Maureen. Speaker 1: 02:02 Contact tracing has been used for decades to control the spread of infectious disease. Can you explain how it works? Speaker 3: 02:09 So contact tracing is one of the, you might say bread and butter methods for control of epidemics. What it does in an epidemic like Ebola is you start with the index person who's infected and you figure out, you, you create a list of people that that person was exposed to and you go talk to each of those contacts. You find out who they were exposed to. You test this network of people and the positives you quarantine so that you are tracking the flow of the virus in the community and then quarantining people and getting them. Uh, you know, ideally if we have treatment, we treat them, um, getting them out of circulation so that you make it much harder for the virus to spread around. How do the attractors, the contact tracers, how do they track down the people who may be contacts? And what kind of questions do investigators ask? Speaker 3: 03:09 Testing takes, uh, at least, you know, unless it's the rapid test, it takes at least a few hours or days when the person is notified that they're positive, they'll probably be a telephone interview to get a list of contacts. So what kind of person is a contact? Well, the County of San Diego defines a contact as somewhere. Anybody you had contact with between 48 hours before symptoms began, uh, with your COBIT infection until the coven person is no longer required to be isolated. And we define a contact as somebody you spent at least 10 minutes with within six feet, or had unprotected contact with their body fluids or secretions, um, including, but not limited to being coughed on or sneezed on, sharing utensils or drinking out of the same container. So it gets hard to do contact tracing, harder to define a contact, um, or to take anyone out of your contact list if you never were symptomatic at all. Speaker 3: 04:11 Uh, for the people that have symptoms, they would think back to two days before their symptoms started, make a list of anyone they spent at least 10 minutes with within six feet. And then those people would be followed up with and tested as well. And what happens if one of the contacts is experiencing symptoms? Same thing. You start over again with them as the case. So, um, you test them and if they're positive, you get all of their contacts and you follow this network until you've exhausted it. There's no more, so you can see it's really quite a huge job. What's your take on the governor's plan to get 10,000 contact tracers on the job in California? Is that too few going to take them too long to train? What's your feeling about that? I think it's a great start and it can be right sized after we see how hard the job's going to be. Speaker 3: 05:03 I think a lot of the contact tracing can be done on the telephone. Um, and if they get some apps that people are willing to use, it'll be, the apps are interesting because they can actually, you can put an app on your phone and the app can, if you're a COBIT positive person, the, your phone knows where you've been all this time geographically. So they're talking about apps that can actually notify people that have been in that same area by virtue of their phone GPS and let them know that somebody's code would positive, might have been in their vicinity at the same time. That's the kind of technology I don't believe we've ever had, um, for contact tracing. I think having a trained workforce reporting to the County or city health departments carefully supervised, um, is absolutely necessary to contain the epidemic. And the main thing we want to do is find the people who have active viral spread and make sure they don't infect many more people. Um, and if that can be done, we will get the virus to die out in our geographic area much quicker. Speaker 1: 06:10 Why is it so important after the stay at home order is lifted, that contact tracing really kicks into gear. Speaker 3: 06:18 It's so important then because we're all back outside. We're all at an, at an increased probability of being within six feet of each other. We're circulating again. We're doing our jobs. We aren't going to be, it's not going to be this easily easy to stay, uh, socially distanced from one another. And that's how the virus loves to get from person to person. Speaker 1: 06:40 Do you have any concerns about the, um, potential pitfalls of relying on apps? Some have raised privacy issues. How would you balance protecting public health with protecting our privacy and civil liberties? Speaker 3: 06:54 Well, I think if people aren't comfortable with the phone apps, they don't need to use them. And um, I've been thinking a lot about, um, what they've made work in other countries, some very unusual things. Like in South Korea for example, they would actually sound an alarm if somebody who was covert positive, uh, came within a certain geographic distance of you. So everybody knew it was anonymous supposedly, but of course people were curious and um, it was very stigmatizing. So if people don't want to use phone apps, that's fine. The method of reliance and contact tracing is really what we call shoe leather epidemiology. It's always been done going from house to house, investigating contacts. And we don't go house to house in this epidemic because we don't want to spread the virus ourselves, uh, by going house to house. But we can use, you know, landlines we can use, we can use regular telephone calls and text messages, for example, um, to communicate with people. And so it's, if people are uncomfortable, I don't think this requires a giving up of your privacy except to reveal the people that you've had close contact with. And you could say, well, I don't want to do that. Um, that's probably your, you're right. But it, it also, I mean, I think we're faced with many situations during this pandemic where we have to decide if we're willing to give up a little bit of our freedom, a little bit of our privacy to protect the whole society. And that's the nature of public health. Speaker 1: 08:28 I've been speaking with Andrea LaCroix, professor of epidemiology at UC San Diego, and thank you so much for your time. I appreciate it. Speaker 3: 08:37 Thank you. Speaker 4: 08:46 [inaudible].

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California Gov. Gavin Newsom announced a plan this week to train 10,000 contact tracers. The state is also exploring the use of digital apps to backtrack the movement of sick people and find out who they may have been in contact with.
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