Specific steps to take:
1) To see the new COVID19 tracing app on your iPhone, go to: Settings/Privacy/Health, click on Health, and there it is. If you do not see it, it will pop up with the next iOS update.
2) To disable/turn off this app, go to: Settings/Privacy/Health, click Health, then click on "COVID-19 Exposure Logging," then turn it off by sliding the green button to gray.
3) Additional protective measures will include turning Bluetooth off, since the app works through your Bluetooth function (go to: Settings/Bluetooth, then click on Bluetooth, then slide the green button to gray/off).
4) You should also turn off "Location Services" (which tracks your location) by going to: Settings/Privacy/Location Services, then click on location services, and slide the green button to gray/off).
[Note that these last two steps (i.e., disabling Bluetooth and Location Services) may impede your ability to use GPS services for directions while driving. So you have a decision to make.]
5) Finally, if you have not yet received the COVID-19 tracing app, it will be coming on your next iOS automatic update. To prevent the automatic uploading of the app, simple turn off automatic updates (go to: Settings/General/Software Update/Automatic Updates, then clicking on Automatic Updates, slide green button to gray/off).
6) It may also be a good idea to disable the Motion & Fitness app (which tracks your movement, ostensibly for health purposes) by going to: Settings/Privacy/Motion & Fitness, then clicking on Motion & Fitness, slide the green button to gray/off.
If you take these measures, you will have done all you can do to keep Bill Gates out of your personal life.