But the new state apps may still be viewed skeptically by a public reluctant to submit to digital tracking. And the early experience of these states is raising questions about whether locally developed apps will gain enough critical mass to help health officials keep tabs on the virus before new hot spots explode. At least one state, North Dakota, is now embracing the Apple-Google collaboration.

Regardless of states’ differing approaches to digital contact tracing, public health experts agree they face a high hurdle getting enough people to trust virtual surveillance to make the effort worthwhile. Almost 60 percent of Americans said they couldn’t or wouldn’t use the system Apple and Google are developing, according to a recent Washington Post-University of Maryland poll.

“Either you have a system unlikely to help people navigate their world, to leave their house and feel safe, or you have privacy trade-offs.” said University of Washington Law School professor Ryan Calo, who recently co-authored a study that found widespread public discomfort with contact tracing technology.

The North Dakota app relies on nearby cell towers and Wi-Fi to follow users’ GPS locations. The state says the technology protects privacy by assigning users a random ID number for tracking movements, and it does not collect personally identifiable information.

Vern Dosch, who heads North Dakota’s contact tracing efforts, said officials believed this approach was better suited for the sparsely populated state — but location data has turned out to be spotty, given that over 20 percent of the population doesn’t have broadband at home. Some app users have complained it often failed to log where they spent time or placed them in locations they never visited.

Fewer than 34,000 North Dakotans have signed up so far, below the state’s original goal of 50,000 — and well short of the 100,000 that Dosch said would provide the state with a much fuller picture. Dosch’s team is working on a marketing campaign aimed at boosting enrollment and addressing residents’ privacy concerns.

In a reversal, residents later this month will have the choice of using a new version of the app incorporating Google’s Bluetooth technology. Dosch acknowledged the state’s decision to partner with the company might worry some, but he said it’s more important to have accurate data on the virus.

“While there’s no question we’ve gotten people who have voiced concerns, and there’s always conspiracy theories out there, in the end it’s about risk and reward,” Dosch said. “We want to fall on the side of giving our citizens every protection we can give them, and if that involves aligning with Apple and Google, then that’s what we’re going to do.”

Utah is also building a GPS-based app that lets users share their location logs with contact tracers. It also captures users’ names and phone numbers with their consent. A spokesperson for the state health department stressed this information would be kept in an anonymized database that staff would manually have to match.

The rollout of the app’s GPS feature was scheduled for this week but has been delayed by technical issues, said spokesperson Tom Hudachko. A slimmed-down version of the app in the meantime has been used by about 47,000 people. Even a few patients sharing information with contact tracers through the technology could prove helpful, Hudachko said.

Several states, including Georgia, are avoiding tracking technology altogether. Instead, they are making apps that let infected patients provide local health information about who they may have exposed.

“This is not the government tracking you,” Georgia health commissioner Kathleen Toomey said this week. “Our app is not one that monitors your every move as you’re driving around. It’s just designed to help our staff monitor cases without having to call everyone.”

However, Georgia’s reliance on self-reporting could leave gaps that make it harder to hunt down potential contacts — especially with more people venturing out into public places as stay-at-home orders are lifted.

There’s widespread agreement any contact tracing app is likely to have drawbacks. For instance, experts say the Apple-Google collaboration’s use of Bluetooth technology, which can penetrate walls, may deliver false results in dense areas like apartment buildings. Lawmakers and advocates have also raised concerns that many of those most at risk of infection — including low-income people and the elderly — either don’t use smartphones or can’t afford the Wi-Fi or cellphone service necessary for these digital tracing tools.

Instead of relying on unproven location-tracking technology, some public health and consumer advocacy groups have urged the use of apps that allow people who test positive for Covid-19 anonymously message recent contacts. Some private health labs and state contact tracers have already started directing people to TellYourContacts.org, a nationwide site launched this week that doesn’t collect any user information.

This type of online tool has been used for STD prevention for the past 20 years, said Jeffrey Klausner of UCLA’s public health school. While these reporting systems may have information gaps because they rely on users voluntarily sharing information, it can help speed up the notification process when time is of the essence, he said.

“These digital tools offer great immediacy and timeliness,” said Klausner, a former official at the San Francisco Department of Public Health. “When the person gets their test results, they can begin the contact notification process within minutes.”

Still, the biggest hurdle remains getting people to agree to monitoring on an unprecedented scale. State and local officials grappling with that challenge are drawing up new messaging campaigns to encourage people to participate.

Ultimately, the task of convincing people to download these apps may fall to the thousands of contact tracers states are training to manually track the virus. These conversations will require sensitivity to people’s privacy concerns about the technology, said J.T. Lane, chief population officer at the Association of State and Territorial Health Officials.

“You need to learn everything you can about their culture and maybe even their previous relationship with technology,” Lane said, including “how stigma and discrimination might be playing a role in that particular group or culture.”