Why NSW's Covid-19 infections are on the rise

After months of declining cases, Covid infections are on the rise again in NSW.

NSW recorded 560 cases and three deaths on Saturday — its highest daily tally since October 9, two days before lockdown lifted.

Three of the new infections are the Omicron variant, bringing the total in the state to 45, with health authorities expecting genomic testing to soon identify more.

Health authorities are attributing festive social gatherings for the increase and are urging residents to be careful.

"Clearly we have seen a number of outbreaks recently across Sydney," NSW Health's Dr John Hall said on Saturday.

"That is why it's so important, as the festive season and Christmas approaches, that everyone remains vigilant when gathering to celebrate with friends, family and colleagues.

"We reiterate just how important it is for people to not attend social functions if they have any symptoms, even if mild."

Chief Health Officer Kerry Chant said this week that she has seen an increase in "transmission in larger social venues such as pubs, clubs and party settings".

La Niña contributing to Covid rise, expert says

Although end-of-year parties have been cited as a breeding ground for the virus, the La Niña weather event sweeping the Eastern states of Australia is also contributing to the spike in cases, an expert says.

Epidemiologist Angela Webster told the ABC a combination of more people gathering and being forced to hold events inside due to bad weather is a factor in the jump in infections.

"The impact of the weather of course is that people don't want to be outside and they close doors and windows," she explained.

"And so when people have been coming together to celebrate the end of the year, they've been doing more so in indoor environments that may not be well ventilated."

Authorities concerned about several events

NSW Health is already battling to contain several large transmission events.

A trivia night at a Sydney pub has sparked a new cluster of cases, with at least 46 patrons testing positive to the virus after attending the Oxford Tavern in Petersham on November 30.

Authorities are also concerned about 140 passengers who embarked on a Sydney Harbour cruise on Friday night. The event has so far resulted in five cases of the Omicron variant.

NSW Health has also issued alerts for the Golden Sheaf Hotel in Double Bay and the Albion Hotel in Parramatta.

Woody's Surf Shack Night Club in Byron Bay has also been linked to at least three cases, while an event at the Coorabell Hall on Saturday night has resulted in 16 cases so far.

There are 150 Covid-19 cases in hospital, with 25 people in intensive care.

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Victoria records 1193 cases, 13 deaths

Victoria reported a slight drop in case numbers on Saturday, recording 1193 cases and 13 deaths.

There are 323 people in hospital with the virus and 68 people in intensive care, with 92 per cent of the population over 12 fully vaccinated.

The state has also been hit by wet weather in the past week, with flood warnings issued for eastern Victoria on Thursday.

With AAP

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