A sellout crowd watches the 2021 Toyota AFL Grand Final match between the Melbourne Demons and the Western Bulldogs at Optus Stadium on September 25 in Perth, Australia, with millions more tuning in on TV.
CNN  — 

Fans who gathered to watch two Victoria-based rivals play in one of Australia’s top sporting events are partly to blame for a more than 50% increase in the state’s daily reported Covid-19 cases, local officials said Thursday.

Victoria reported 1,438 new infections Thursday, up from 948 the previous day – a surge the state’s pandemic response head said was the result of “significant numbers of social gatherings” that coincided with the Australian Football League (AFL) championship match between Melbourne Demons and the Western Bulldogs on Saturday.

“(We’ve seen) grand final parties, other social gatherings, barbeques, backyard visits – and all of this has generated significant additional caseload,” Jeroen Weimar said at a news conference. Up to a third of the new cases could be attributed directly to the gatherings, he added.

The AFL grand final is a significant event in Australia – especially in Victoria, where the sport originated and which celebrates the Friday before the game as an official public holiday.

However, with Victoria in hard lockdown since August as the state attempts to bring a local outbreak of the highly contagious Delta variant under control, the final was moved to Perth, Western Australia.

The championship match is the Aussie rules football equivalent of the NFL Superbowl, with almost 3 million people tuning in across Australia to watch on September 25 – about 12% of the population.

Thursday’s rise in case numbers is a “significant setback,” Weimar said, as demographics of those infected indicate the virus has spread further than usual. About 55% of the new cases were reported among men, many of whom were disproportionately younger, he said.

People had “dropped their guard” over the weekend, Weimar added.

“(They) decided now it’s a grand final weekend, it’s a long weekend, we deserve a bit of a payback. And that has now translated into at least 500 additional cases,” he said.

The Melbourne Demons won the grand final, ending the club’s 57-year wait for the championship.

The Victorian government has said it will relax restrictions on people’s movement once 70% of its population has been fully vaccinated, but the state has recently seen violent demonstrations by groups opposed to the lockdown.

As of Thursday, almost 50% of Victoria’s population had received two doses of a Covid-19 vaccine.

Speaking at the news briefing Thursday, Victoria Premier Daniel Andrews said the fresh wave of cases was “completely avoidable” but ruled out a link between the surge and protests last week due to a lack of evidence.

CNN’s Wayne Chang contributed reporting.