1/n People who seem to lack a clear background on the history of public health interventions seem to be deliberately or inadvertently distorting the role of cell phone apps in case based interventions to control spread of deadly disease. So here’s another primer for them.

2/n The idea is this: When someone tests positive for #COVID19, or is exposed to it, that person would be required to self-isolate. This is to prevent spread. Identifying cases, and requiring people who are positive to self isolate, is the core of case based interventions.

The alternative to case-based interventions (testing people, identifying positive cases, requiring people who are infected to self isolate) are population based mitigation. That is what we are doing now. Isolating entire populations rather than just the individuals who are sick.

4/n Ideally, as epidemic spread wanes, we want to move toward case-based interventions and away from population based mitigation. We need few things to do that. First and foremost, we need broad surveillance tools for testing and identifying #COVID19 cases https://apple.news/ARg473RGESuej9i90TkVJzA

5/n But when you identify positive cases, what do you do? Ideally, you want to require asymptomatic or mildly symptomatic people to self isolate for the duration of illness, so they don't spread infection and trigger outbreaks. But how do you enforce that?

6/n In the past, it has sometimes been enforced with public health case workers doing visits. Other times, it has been enforced with police. Here is how @HHSGov currently describes the use of police to enforce public health orders and self isolation. https://www.hhs.gov/answers/public-health-and-safety/how-is-isoloation-and-quarantine-enforced/index.html

7/n But technology provides another way. Some countries, including U.S., have used cell phones to check in on people to make sure they are adhering to public health orders. Sometimes it is with text messages to check in on symptoms. Other times apps to make sure people stay home.

8/n Some countries have used these apps to make sure contagious people don't break a self isolation. Again, the idea is to monitor only those with active infection, known to be infectious, to prevent spread. It's a key element of case based interventions. https://www.technologyreview.com/s/615329/coronavirus-south-korea-smartphone-app-quarantine/

9/n There's a lot of deliberate misinformation and fear mongering that's plagued our response. We need to be level headed about what we need to accomplish. The goal is widespread surveillance and containment of active infection so we don't have to live with constant epidemics.

10/n Case-based interventions that use traditional tools of "tracking and tracing" of infection and contacts is key to these efforts. One way or another, it'll require means to monitor people who must self isolate, including those traveling into U.S. who are actively infected.

11/n If we don't get the tools in place by Summer for widespread testing thats available in doctors' offices and easily accessible to patients, and ability to do vigorous track and trace of infectious people, we'll almost certainly have large outbreaks and maybe another epidemic.

12/n Our technology can help us solve this crisis. A big part of it will be getting a safe and effective drug. That's obtainable. Also key is solid surveillance system coupled to robust case-based measures. We can use tech to help prevent future outbreaks. https://healthpolicy.duke.edu/sites/default/files/atoms/files/covid-19_surveillance_roadmap_final.pdf