Apple and Google launched a major joint effort to leverage smartphone technology to contain the COVID-19 pandemic.

New software the companies plan to add to phones would make it easier to use Bluetooth wireless technology to track down people for who may have been infected by coronavirus carriers. The idea is to help national governments roll out apps for so-called “contact tracing” that will run on iPhones and Android phones alike.

Software developers have already created such apps in countries including Singapore and China to try to contain the pandemic. In Europe, the Czech Republic says it will release such an app this month. Britain, Germany and Italy are among other countries developing such apps.

Privacy and civil liberties activists have warned that such apps need to be designed so governments cannot abuse them to track their citizens. Apple and Google plan say user privacy and security are baked into the design of their plan.

Security experts also note that technology alone cannot effectively track down and identify people who may have been infected by COVID-19 carriers. Such efforts will require other tools and teams of public health care workers to track people in the physical world, they say. In South Korea and China, such efforts have included the use of credit-card and public-transit records.

Given the great need for effective contact-tracing — a tool epidemiologists have long employed to contain infectious disease outbreaks — the companies will roll out their changes in two phases. In the first, they will release software in May that lets public health authorities release apps for both Android and iOS phones. In coming months, they will also build this functionality directly into the underlying operating systems.

On Friday, the companies released preliminary technical specifications for the effort, which they called “Privacy-Preserving Contact Tracing.”