Earlier this week, there were six confirmed cases of coronavirus among guests who attended the wedding at Tumbling Waters Retreat on March 6.

That number has since risen to 31, with a further four people who were close contacts of the wedding guests also diagnosed with COVID-19.

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The cases are potentially linked to travel from the US.

"To midday on March 19, there have been 26 NSW residents who attended the wedding who have been diagnosed with COVID-19," NSW Health said in a statement.

"There are another four NSW residents with COVID-19 who are close contacts of wedding attendees with COVID.

"NSW Health is aware of another five people with COVID-19 who attended the wedding but live interstate."

NSW Health is working with other states and territories to notify attendees at the wedding of their potential exposure to COVID-19 and the need to quarantine themselves until March 20, including Tumbling Waters Retreat staff.

Tumbling Waters Retreat posted an announcement about the staff quarantine to its Facebook page on March 17.

"At 4pm today I have been advised by NSW Health Department-the staff that worked front of house on the 6th March Wedding need to self isolate as a matter of caution until the 20th March 2020 ...and this is exactly what we are doing. No other guests, staff/ suppliers that were not in close contact with the wedding guests need to worry," the post reads.

"Our manager Karen Hart and the rest of the team that did not work at the wedding are not required to self isolate, it is business as usual.... along with the new added industry operational precautions.

"I am truly sorry the angst this may have caused some of our guests and on behalf of all our team we are trying our very best to keep you updated, informed and safe during these terrible times. Let's hope a vaccine is found soon."