Influenza rates have risen by 70 per cent in Hunter New England in a week, health data shows.
COVID hospitalisations are falling and the latest wave appears to have peaked, but high levels of the virus are spreading.
Peter Murray, a public health physician, said "we've got the perfect storm at the moment unfortunately".
"We've got high levels of COVID and influenza, RSV and lots of pertussis [whooping cough] around," Dr Murray, of Hunter New England Health, said
Emergency department presentations for influenza-like illness had "rocketed up".
"Mycoplasma pneumoniae [which causes pneumonia] is circulating as well," he said.
Hunter New England recorded 1853 flu notifications in June to date, almost triple the previous month.
The district recorded 830 flu notifications in the week to June 22, compared to 489 the previous week.
These figures account for people unwell enough to take a PCR test.
Dr Murray urged people to "get your flu vaccine if you haven't had that already".
"We are tracking a little lower than last year, which is a concern for us," he said.
"It's still a good time to get vaccinated. We strongly encourage people to do that."
A fortnight ago there were 102 COVID hospitalisations in the district, with six in intensive care, and 35 aged-care facilities with COVID outbreaks.
There were now 60 COVID hospitalisations, with one in intensive care, and 38 respiratory outbreaks in aged-care - mostly due to COVID.
"This was a significant COVID wave. We had really high hospitalisations, but they are dropping now which is great," Dr Murray said.
"Hopefully we're over the peak of this COVID wave. The driver of this wave has been the KP.3 variant."
Like other recent waves, the "variants are very good at getting around the immune system - previous immunity from infection or vaccination".
"Fortunately the variants circulating now aren't more severe. We monitor that very closely."
Dr Murray said flu activity was on the "upward side of a wave".
"RSV [respiratory syncytial virus] looks like it's stabilising and perhaps dropping slightly."
He also urged people to "stay up to date with their recommended COVID booster dose".
"Staying home when you're sick can help reduce the spread in the community, workplaces and schools."
Those with symptoms who have to go out should wear a mask.
"For people at risk of severe COVID, have a plan with your GP to access PCR testing and antivirals."
The NSW Respiratory Surveillance Report, released on Thursday, said "pertussis and pneumonia continue to be unseasonably high in schoolchildren".
They can cause "persistent cough, wheezing and pneumonia".
"There have been unseasonably high presentations to emergency departments in NSW for children and young adults with pneumonia, particularly those aged 5 to 16," the report said.
"Mycoplasma pneumoniae is a common cause of pneumonia in schoolchildren and epidemics occur every three to five years."
The all-cause death rate per 100,000 people, which covers all ages and conditions, was below the baseline in NSW, the report said.
