Apple and Google unveiled an ambitious effort Friday to help combat the novel coronavirus, introducing new tools that could soon allow owners of smartphones to know if they have crossed paths with someone infected with the disease.

The changes the two companies announced targeting iPhone and Android devices could inject valuable new technological support into contact tracing, a strategy public health officials say is essential to allowing people to return to work and normal life while containing the spread of the pandemic.

Apple and Google are hoping to harness Bluetooth, a technology typically used to connect device owners’ wireless speakers and keyboards. With the aid of the technology, public health officials soon would be able to deploy apps with the ability to sense other smartphones nearby. If a person learns they have the coronavirus, they could indicate on their app they’ve been infected — and people whose smartphones have been in their vicinity would be notified, regardless of whether their devices run on Apple or Google software.

Apple and Google said they expect to make tools available to developers to assemble such contact-tracing apps as soon as mid-May, with further enhancements to the operating systems, expanding the systems’ reach, to follow.

The companies said the technology would not track a user’s specific location, nor would they reveal an infected person’s identity to the tech giants or to governments worldwide.

The announcement marks an unprecedented collaboration between the two tech rivals, among the country’s largest corporations. But the success of their efforts will hinge on whether public health officials can create apps fast enough, and whether people download and use them consistently. Most of all, it relies on the widespread availability of testing, a lingering challenge in the United States, where many Americans still cannot figure out if they’ve contracted the coronavirus despite recent claims from President Trump.

“All of us at Apple and Google believe there has never been a more important moment to work together to solve one of the world’s most pressing problems,” the firms said in a joint statement. “Through close cooperation and collaboration with developers, governments and public health providers, we hope to harness the power of technology to help countries around the world slow the spread of COVID-19 and accelerate the return of everyday life.”

The new partnership reflects a growing recognition in Silicon Valley that popular tech devices — and the troves of data they generate — can be put to new use in tracking the pandemic.

In recent weeks, Facebook has sought to leverage social data about its users’ whereabouts to help track the potential spread of the coronavirus. Apple and other companies debuted special symptom checkers to help people determine if they need care. Google released detailed data about smartphone users’ travel habits in 131 countries. And some marketers, once unknown to most Americans, have claimed to help public health officials track the effectiveness of social distancing around the globe.

But some of these sites and services have raised uncomfortable questions about the balance between public health and privacy — and how to safeguard people’s personal information even in the face of an urgent need to save lives from a deadly infection.

When White House officials last month began engaging the tech industry about ways to harness location information — discussions first reported by The Washington Post — privacy hawks and some lawmakers balked. Many feared the government could encroach on Americans’ private lives.

On Friday, Apple and Google stressed they would not be collecting anyone’s precise coordinates for the purpose of combating the coronavirus. Instead, a device with a contact-tracing app would broadcast a unique signal every few minutes to other devices nearby, including those that come within six feet. The Centers for Disease Control and Prevention has recommended six feet as the minimum for social distancing.

For now, users would have to choose to install these contact-tracing apps, which are still under development by institutions such as the Massachusetts Institute of Technology. And it would be entirely up to the individual to indicate if they had contracted the virus, resulting in anonymous alerts being sent to those who had been in that person’s proximity.

Epidemiologists and public health officials have recently zeroed in on Bluetooth technology as a vital tool for human teams seeking to trace and stem the pandemic’s growth. Developers said it would complement human contact-tracing efforts, in which public health officials interview people to find out whom they made contact with at the time of their infection.

In late March, a research team at the University of Oxford, writing in the journal Science, said the spread of the coronavirus is “too fast to be contained by manual contact tracing,” and a Bluetooth-like technology would be needed to complement it. Such an app could “replace a week’s work of manual contact tracing with instantaneous signals transmitted to and from a central server,” they wrote.

“The intention is not to impose the technology as a permanent change to society, but we believe it is under these pandemic circumstances [that] it is necessary and justified to protect public health,” researchers said.

Some experts still point to challenges with the technology, including that devices might link between walls, car doors or different floors of the same building even when people don’t come in close contact. Human investigators using low-tech interview techniques, they argue, will be critical to determine actual risk.

“Bluetooth has promise, but it is extremely experimental and has problems,” said John Scott-Railton, a senior researcher at the Citizen Lab at the University of Toronto’s Munk School of Global Affairs and Public Policy. “We’ve all spotted our neighbor’s Bluetooth speaker through a wall or a floor. Or seen someone’s headset in a traffic jam. That doesn’t mean we will ever come within droplet distance of them. Until engineers reliably figure out how to map Bluetooth onto droplet distance, the approach is bound to yield a lot of false positives.”

With Apple and Google, an added challenge is that it’s entirely in the hands of users: Because the system is voluntary, it relies on people downloading and using the app properly. To address concerns about potential abuse, users would have to get a confirmed diagnosis from a public health agency that they have the coronavirus — along with a special code, for example — that triggers the signal to other devices, according to Apple.

Privacy advocates view the use of Bluetooth technology in this way as both more useful and less invasive than other experiments using cellphone location data that have surfaced in recent weeks, as the pandemic has deepened. While smartphone users have little or no ability to control the data collected by telephone companies and app makers about their movements, they can turn off Bluetooth or refuse to download the proposed coronavirus tracking apps.

“To their credit, Apple and Google have announced an approach that appears to mitigate the worst privacy and centralization risks, but there is still room for improvement,” said Jennifer Granick, ACLU surveillance and cybersecurity counsel, in a statement on Friday. “We will remain vigilant moving forward to make sure any [contact] tracing app remains voluntary and decentralized, and used only for public health purposes and only for the duration of this pandemic.”

Singapore has shown some early success through its Bluetooth tracking app, TraceTogether, which links people’s infection status to their phone number. Officials in Germany and France and across Europe have discussed a similar Bluetooth system that could track the outbreak’s spread while preserving users’ privacy.

But getting even limited impact could be a challenge. Singapore’s app, which launched last month, uses Bluetooth to identify when people have been within six feet of each other for at least 30 minutes. If an infection is confirmed, officials with the government’s health ministry call the person to pursue aggressive quarantine actions.

A top Singapore official said earlier this month that three-quarters of the nation’s population would need to download the contact-tracing app for it to be effective — but that only one in six people, or roughly 1 million Singaporeans, had installed the app so far. Singapore’s prime minister, Lee Hsien Loong, said in a national address last week that the efforts had failed to fully blunt the outbreak: “Despite our good contact tracing, for nearly half of these cases, we do not know where or from whom the person caught the virus.”

The Apple and Google effort could help unify the efforts of a growing team of researchers that sees Bluetooth’s short-range, low-power technology as a way to track social spread. The tech giants’ contribution could also help the teams surmount some technical hurdles that prevented the systems from functioning reliably during recent tests.

Bluetooth-based systems would not be a “silver bullet” toward tracking infections and would only complement other efforts, said Rhys Fenwick, the communications chief for one of the groups, Covid-Watch, working on such technology. He compared the idea to wearing masks: Though many people still won’t use them or may use them wrong, encouraging their use could help chip away at a vast global-health risk.

“It doesn’t have to be a perfect system,” he said. “It just has to be better than the status quo.”