Figuring out who has been exposed to a disease is a herculean task. We are constantly moving about and interacting with people, far more than we realize. For example, do you remember how many people you passed by last time you were in the grocery store?
There has been some effort to use our phones as a way to perform automatic contact tracing: participating devices exchange signatures as they pass close by each other and maintain a list going back through the past several weeks. If someone tests positive, they can send an anonymous alert to all of the devices still within the exposure window that their owner should get tested.
California’s Android app version of this is called CA Notify, but there are versions for a number of other states as well. On iPhones, you can simply opt-in to exposure notifications without using a dedicated app at all. It’s only as good as the number of people participating, but with the virus surging once again, it’s one more way to help protect yourself and people you care about.
No official app, various links that don’t seem to go anywhere.
No app, report online.
This and other COVID-19 resources are also collected in a separate post.