Washington’s post-9/11 debate about how much surveillance a free society should allow has suddenly become about much more than counterterrorism and national security. Amid today’s global pandemic, key technology companies are in talks with federal and state governments about employing their tools against Covid-19. Facebook , which holds a trove of geolocation information, is sharing disease-migration maps. Clearview AI, a facial-recognition tech firm, may be able to track infected patients and identify people they have met. Smart thermometers are recording and transmitting fevers in real time. The data firm Palantir is working with the Centers for Disease Control and Prevention to collect and analyze vast information streams.

All this and more, we hope, will help to stop the virus in its tracks, save lives and help Americans get back to normal. But such efforts—done in haste—also raise searching questions about the balance between privacy and public health. Decisions being made on the fly by governments, private firms and individuals will change the country’s digital social contract for years to come.

China’s approach to monitoring its infected citizens is famously authoritarian, with a new app telling users whether they can move freely based on a personal health analysis—and, not incidentally, sharing their location with the police. Citizens in democracies would no doubt reject such intrusive measures, but the pandemic has spurred key countries to consider new infringements on privacy.

British officials, for example, hope to roll out a new smartphone app that will alert users who have come in contact with an infected individual, using location data drawn from GPS, Wi-Fi networks and even Bluetooth beacons. A separate app, developed by researchers outside of government, will map British infections and share information with officials. Its developers say the U.K. government can delete the data at some point and pledge not to publicize the movements of infected patients.

But South Korea has done just that. By analyzing cellphone locations, CCTV feeds and bank transactions, Seoul has established a publicly available website that tracks individual locations and contacts. Interested observers have already mined the data to make guesses about who is visiting “love hotels” and having affairs. Meanwhile, Israel’s Shin Bet domestic security service has established a system that combines individuals’ credit history with cell-based location information—and works even if a phone’s tracking is disabled.