As states and territories begin the first stage of relaxing lockdown measures some Australians have chosen to flout the rules and head out to party.

A resident of Princes Hill in Melbourne’s north told The New Daily she had seen two large groups partying in Princes Park, a popular spot for locals, on Friday night.

“I was walking through the park with my dog and saw a group of at least 30 teenagers drinking together in the park,” she said.

Victorians are only meant to socialise in small groups of no more than five guests to a home.

Queenslanders play football with friends as they picnic at the Kangaroo Point. Photo: AAP

Later on her way to the supermarket, the resident saw another group of about 15 adults standing around and drinking.

“It was outrageous and disheartening considering all the efforts we have been making to practice social distancing over the last few months.”

• Related: Worrying sleeper cases detected as Australians come out to play

On Saturday, Victoria recorded 11 new COVID-19 cases, while the number connected to an abattoir in Melbourne’s west grew to almost 100.

As many Australians get to sit in pubs and socialise with mates for the first time in months, infectious disease experts are warning us to be careful.

“We need to be careful because the virus is still around,” Australian National University infectious disease physician and microbiologist professor Peter Collignon said.

“The basic things we need to do to stop the droplets spreading are keeping up the 1.5-metre distancing, washing our hands and avoiding crowds, whether that’s of five people, 10 or 20 will change depending on the rate of transmission.

“Those fundamental principles we have to maintain for the next five, six months, but maybe even a couple years. This virus is still around.”

To avoid a second wave, we all need to be vigilant, he said.

“We don’t all need to be hermits in our houses, but we have to accept this virus is still around and therefore we have to do everything we can to decrease the risk.

Simon Smith and Tanja Wii are seen taking part in an online class. Photo: AAP

“What we want is physical distancing, not social distancing.”

Part of the concern is that whenever restrictions are lifted, we won’t see if it has caused an outbreak until weeks later, he said.

“Well, basically the average incubation period is five days, so whenever you change anything it takes five to 10 days to see the effects of that.

“I’m all for not having people in lockdown in their houses and we don’t have to do that, but by the same token getting out means you have to keep up the basic rules. Winter is the next danger.”

Cooped-up Australians were quick to seize on the relaxation.

In Queensland and New South Wales cafes, parks and playgrounds were buzzing with activity.

The eased restrictions saw exercise classes returning to Brisbane’s New Farm Park, where fitness trainer Chris Tuck coached his first group in 10 weeks.

“It’s awesome to be back together again, feeding off each other’s energy,” he said of the six people he had just finished training.

Many families were out and about as children clambered into playgrounds that had been closed to control the spread of the virus.

“She is loving it,” mother-of-two Jo Williams said as she pushed her four-year-old Hannah on a swing in the same park.

“Both the kids have missed the outdoor activity and interacting with children.”

In Sydney’s inner west, Shannah Baichoo was among the first to return to popular Summer Hill bar The Rio, resuming what was once a regular Friday night ritual with her husband.

“It’s like a signifier of life becoming normal again. It feels amazing,” Ms Baichoo said.

For The Rio’s operational manager, Fabrizio Culici, pouring his first beer into a glass pint felt “phenomenal” after weeks of takeaways and deliveries.

“The sense of relief is just fantastic,” Mr Culici said.

“We just hope … that this is certainly not going to be a short-lived thing and we go back to deliveries because it’s going to be very hard to survive if that happens.”

-With AAP