Lachlan James Thomas Peters, had attended the Dubbo Showground in NSW's Central West, on August 12 to take a COVID test as part of his employment requirements.

The next morning, the Brocklehurst 19-year-old warehouse storemen and delivery driver at Western Parcel Express, received a negative result.

However, according to police, Peters altered the negative result to say positive, and sent it to a group of friends on Snapchat saying "I'm positive".

One of the recipients, however notified his workplace believing he was a close contact, causing the worksite at Dubbo City Welding to be suspended for the day, while everyone was told to get tested.

Peters was later interviewed by police, and explained he had tested negative, but altered the message and sent it to his friends as a joke.

Police said while Peters "appeared to be remorseful to some degree" he seemed to show little insight into the disruption that he had caused to a business "already hit by numerous difficulties".

"The accused showed no insight at all into how his behaviour impacted the NSW Police Force and NSW Health, and how it could have considerably hampered their management of the unfolding COVID-19 outbreak in the Dubbo LGA and other areas of western NSW districts," police said.

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In Dubbo Local Court on Monday, defence lawyer Geraldyne Keen, on behalf of Peters, pleaded guilty to false representation resulting in a police investigation.

The court heard the penalty for this offence was a $5500 fine, however Ms Keen said he had since understood it was a "silly decision by him".

"He instructs me he was joking around. Only a number of friends received the image, one of them took it very seriously and took it to his employer," she said.

"He's now had the benefit of time to consider how inappropriate his actions were."

Magistrate Theresa Hamilton however had concerns about the format of the charge and wording of the indictment.

"He made [the statement] to his friends, not police," she said.

"I don't know why this statement would have called for a police investigation. It's not a matter that would normally call for a police investigation."

Due to his limited criminal history, young age and his early plea of guilt, Magistrate Hamilton dismissed the charge.

"He's obviously taken a joke too far, and done something stupid. But it seems to me he shouldn't be convicted for this matter," she said.

"I'm sure he's learned a lesson about the dangers of making these types of jokes."