Gov. Andrew Cuomo spent a large portion of his Thursday briefing on contact tracing efforts in the state, calling it a "massive undertaking."

The concept of contact tracing has been discussed for weeks -- it's a plan to essentially track down people who have been in close contact with someone who tests positive for COVID-19.

On Thursday, Cuomo detailed the state's plan to get a contact tracing program up and running. He was joined by former New York City Mayor Michael Bloomberg, after it was announced last week that he would lead the program.

"Doing that requires a lot of people who are coordinated and managed effectively, it's a very big undertaking because of the scale," says Bloomberg.

The state will use Health Department and other state employees as "contact tracers." CUNY and SUNY are also recruiting possible applicants.

"Johns Hopkins has developed a training class that can be taken remotely," says Bloomberg. "It will cover all the basic information of epidemics, contact tracing and privacy."

Cuomo says the estimate so far is that 30 contact tracers will be needed for every 100,000 people in the affected area -- which would mean 6,400-17,000 tracers statewide.

Bloomberg also announced three smartphone apps are in development right now.

"The first will help contact tracers find information and data quickly, the second will help the public provide information to health departments, and the third will allow those in quarantine to access the guidance and services they need," says Bloomberg.