With the federal government's controversial new COVID-19 tracker app yet to be launched, a little bit of detective work is needed to determine who might have come into contact with a confirmed case.

In the Western NSW Local Health District, 45 people people have tested positive and at each diagnosis the Public Health Unit is alerted.

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A public health nurse will be assigned to interview the person who tested positive to determine who they have come into close contact with.

"The infectious period is 48 hours prior to the case [person] developing symptoms, the whole time they are symptomatic and about 24 hours after they have recovered," communicable diseases and immunisation manager Sue Turcato said.

"We ask very definitive questions about where they've been and who they came into contact with.

"Close contact is everybody that's living in the same household or the same household setting.

"A close contact is 15 minutes of face-to-face contact with someone and that can be accumulative. So if you've spent three five-minute periods with them that counts.

"Two hours or longer in the same room with someone also counts."

People who have been seated near a confirmed COVID-19 case on a plane are also considered a close contact.

Ms Turcato said it can be difficult for some people to remember exactly who they have come into close contact with, and in some instances it can take a couple of interviews to get the information.

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"Once we've developed that close contact list we then contact all of those people and let them know ... and advise them to go into self-isolation for 14 days," she said.

Health workers will keep in touch with people who have been asked to self-isolate.

"It's an all-round welfare check because they're not confirmed cases themselves, it can be very isolating," Ms Turcato said.

"We also liaise with other services if people live alone."

Ms Turcato said a lot of misinformation had been spread on social media, but she wanted to assure the community that anyone who had been identified as a close contact would be contacted by the Public Health Unit.

"There's a lot of things that are written on social media that aren't true and that's been difficult," she said.

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While the COVID-19 pandemic might be new, contact tracing is not and has always existed in the state's health system.

"The Public Health Unit has always been involved in contact tracing such as with measles, whooping cough and sexually transmitted diseases," Ms Turcato said.

"Contact tracing is something we do every day, but this [COVID-19] has just ramped it up."

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