Since the beginning of the COVID-19 pandemic, New Yorkers have had to become familiar with all sorts of concepts that were mostly only known to public health officials and epidemiologists. “Social distancing” and “community spread,” for example, are two terms that many were not familiar with before March.

Even government officials have expressed weariness with all the new language.

“Testing, tracing, testing, tracing, we use these words like people would know what they mean,” Governor Andrew Cuomo said during a press briefing earlier this week.

But the term ”contact tracing” is crucial to the governor’s plan to gradually reopen the state. Here’s a brief rundown on what it is and how it will be handled in New York.

What is contact tracing and why is it so important for getting back to business?

Contact tracing is a method of containing the virus before it can spread too far. It's been used by public health officials for decades to manage outbreaks of diseases like tuberculosis, syphilis, and ebola, but it takes some groundwork to do it well. When a person tests positive for COVID-19, that result is reported to the state and to their local health department. A contact tracer will be notified, and will work with the person to figure out as many people as possible who they had close contact with during the virus’ incubation period, generally believed to last up to 14 days prior to symptoms appearing.

New York City health officials discussed contact tracing in the early days of the COVID-19 pandemic, referring to tracers as “disease detectives,” but the method was put on the backburner when it became clear that infection rates were exploding. As infection rates begin to decline, public health agencies are ramping up their contact tracing programs, even partnering with outside providers.

New York City Health + Hospitals (H+H) begun their contact tracing program last week, with 500 tracers onboarded. The move for H+H to take the lead on this program was significant since it deviated from the longstanding practice of the city Department of Health taking the sole lead. Elected officials interpreted this move as political. Even so, the two agencies are collaborating on the program.

What counts as “close contact?”

It depends on the situation. The U.S. Centers for Disease Control and Prevention guidelines classify it as 15 minutes of close contact, such as chatting with a friend, without wearing masks while riding a train. Contact tracers have some leeway in using their judgement to decide which contacts of a COVID-19 infected patient are at higher risk of infection. The contact tracer will then track down those people and warn them that they may have been exposed to the virus and should isolate themselves for two weeks. Contact tracers are bound by confidentiality laws not to disclose the identity of the infected person the newly infected person came in contact with.

Who is in charge of this, New York City or the state?

A little bit of both. As part of Cuomo’s reopening plan, one metric used to determine whether a county can start reopening is whether it has hired enough contact tracers. Currently, that’s set at a minimum of 30 per 100,000 people. It’s then up to local public health agencies to hire those contact tracers.

For New York City, which has about a population of about 8.6 million, that means hiring more than 2,500 contact tracers. As of this week, city health officials say they are on track to hire 1,000 by June 1st.

To put that in perspective, at the beginning of the COVID-19 pandemic there were about 2,200 full-time contact tracers operating in the entire U.S. China’s Wuhan province, where the pandemic began, has a population of about 11 million people and brought on about 9,000 people to work as contact tracers.

Isn’t former Mayor Michael Bloomberg involved in training tracers?

New York state’s contact training program has been funded by Bloomberg Philanthropies and developed by Johns Hopkins University, where Bloomberg is an alumnus (there's a whole school of public health named after him). Bloomberg donated $10.5 million to put the training program together.

There is an element of politics in how it’s discussed, though: Cuomo likes to reference "Mayor Bloomberg's" contact tracing program, while Mayor Bill de Blasio tends to credit Johns Hopkins University. But at the end of the day, they're talking about the same thing.

All contact tracers (including those through H+H) will be going through the Bloomberg-funded, JHU-designated training program and then fan out to each municipality. Learn more about taking the course here.

What about apps? Can my phone tell me if I’ve been in contact with someone with COVID-19?

There has been a lot of talk in the last few months of using smartphone apps to help contact tracers. Some countries have used apps to track the virus’ spread or enforce quarantines, but that hasn’t been used extensively in the U.S. In April, Apple and Google announced that they were collaborating on reworking their software that would help public health departments make contact tracing apps, but the tech giants are not making the apps themselves. That update was only released this week.

Some companies have released their own contact tracing apps or updates that add that capability, but they generally rely on users self-reporting their COVID-19 test results. Privacy advocates have called that a good thing, but some public health officials argue that actually makes the apps less useful for contact tracing.

In the end, that might mean tracers have to rely more on the tried-and-true methods of going door-to-door and talking to people on the phone for a more accurate tracing.

Where’s the federal government in all this?

In April, President Donald Trump said that a robust contact tracing program is in place nationwide. But it’s really just a patchwork collection of state and local health authorities already stretched to the brink by the COVID-19 pandemic.

Last month, a study that came out of the Johns Hopkins Center for Health Security found the nation will need at least 100,000 contact tracers and $3.6 billion in funding to respond to reopen safely. While states are best positioned to do the legwork, the researchers say they will need federal funding to get it done.