The staff were friendly, the seafood fresh, and more than 80 people came from all over to celebrate with birthday boy Glen Wright – one guest had just flown back from a ski holiday in Aspen, Colorado.

Behind closed doors, the tables were packed with successful figures from Queensland business, finance and development, and their partners. For some, the weekend away was a welcome reprieve from their worries about the looming pandemic and economic crisis. Saturday, March 14 was a special day.

What Wright could not have known, nor possibly imagined at the time, is that his birthday bash would be the scene of a major COVID-19 outbreak, his guests taking the virus back home with them like a party favour. Contact-tracing continues, but it appears the coronavirus came from the US, mixed with the guests and restaurant staff, then spread to Brisbane – where it may have led to a private school closure – and regional centres like Warwick.

To date, more than 20 people have tested positive, including four staff who continued working some days after the party when they may have been contagious. All up, hundreds could potentially have been exposed.

On the weekend of the party, it was already dawning on members of Australia’s business community that their own had been exposed in Aspen. Indeed, on March 15, Australian Financial Review columnist Joe Aston reported on a cocktail party held two weeks earlier in Aspen, with Australian rich-listers, and how “one of the guests immediately returned to Australia, fell ill and tested positive for COVID-19. The news filtered back as if by messenger pigeon, and the soiree’s other attendees self-reported earlier this week”.

At the same time, The Age in Melbourne reported other high-profile Australians to be infected at the American ski resort, including Melbourne GP Chris Higgins, the father of Missy Higgins, who endured criticism he had put his Toorak patients at risk. Today, The Age reported there had been police complaints about another Melbourne couple who had refused to self-isolate since returning from Aspen, and had been seen out and about in the community.

But at the time of Wright’s birthday weekend, there were no such restrictions. On the following Monday, the 16th, returning overseas travellers were ordered to self-isolate for 14 days – too late to stop the infected party guest from Aspen attending Wright’s party. Restaurants have since been ordered to close down tables, and Sails voluntarily shut altogether on March 23 – too late to stop infected staff working afternoon and evening shifts on March 18 and 19, potentially putting other staff and patrons at risk.

Now, non-essential travel has also been banned, and people urged to stay home – too late for the party guests who unknowingly took the virus back to their homes far and wide, belatedly causing concern in their communities.

Since the party, the Warwick butchery of Wright’s brother Peter closed as a precaution, so too, briefly, his local bank, after news on March 20 he had tested positive. It would be several days before the outbreak was revealed, and even then only as a health alert due to the potential for restaurant staff to have subsequently infected other patrons.

Sunshine Coast public health physician Dr Roscoe Taylor said the restaurant had good personal hygiene practices, so the risk of transmission from infected staff to others was considered low. Taylor noted, however, that about 150 people had attended the restaurant on the two days of concern, and it was still unclear how many party guests had been infected. Only a few cases were Sunshine Coast locals.

Wright told The Australian newspaper his brother was “struggling a fair bit with the amount of backlash” over the outbreak.

“It’s hard to believe that one source could get to that many people in a room,” Peter Wright said.

Assumption College at nearby Killarney was also put on alert, reportedly over cases linked to the party, while there has been speculation the temporary closure of St Margaret’s Anglican Girls School in Brisbane this week was linked to another returning guest.

Today, Queensland Health issued further alerts for anyone who may have attended three other venues where a person had been with COVID-19: Land and Sea Brewery at Noosaville at lunchtime on March 13, Sum Young Guys Restaurant at Sunshine Beach around dinner time on March 13, and the Sunshine Beach Surf Life Saving Club on the afternoon of March 14 and around lunchtime on March 15. It was unclear whether this case was linked to the Sails Restaurant cluster.

As the Queensland government sought to restrict access to the state from NSW, enforce more business closures, and make contingency plans for students to stay home, Premier Annastacia Palaszczuk declared an end to holidays and entertaining people in public or even at home.

“This is how coronavirus can spread,” Palaszczuk said sternly, “we can no longer have parties”.

“It is a very clear signal to everyone that this is now not the time to socialise, it is the time to keep your distance.”

There have been another 50 cases of COVID-19 recorded overnight, taking the tally to 493, with a second Queenslander also dying from the disease.