Flu spike points to an early season

More than 9500 cases of influenza have been reported already this year. See how your state is faring.

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With spiralling influenza cases pointing to an early start to the Australian flu season, children are once again proving to be particularly vulnerable.

Latest data from the Department of Health and Ageing shows there have been more than 100 times the number of flu cases so far in 2023 than in the first two months of 2022.

The National Notifiable Disease Surveillance System shows that as of 8 March there had been 9695 notifications of influenza this year – and more than 3000 of those cases are in children under 14.

Australia’s Chief Medical Officer Professor Paul Kelly has called on health professionals to help increase historically low uptake of vaccination in children under the age of five years.

The bulk of cases have been in NSW (3424), followed by Queensland (2372), Victoria (1822), Western Australia (874), the Northern Territory (582), South Australia (510), the ACT (78) and Tasmania (33).

Melbourne paediatrician Dr Daryl Cheng said children, particularly those aged under nine years, have been hospitalised at higher rates than other age groups. This was also seen in 2022.

“There has been increased testing, at least in the paediatric population,” he told The Medical Republic. “We test now when they do come to hospital for flu, RSV, and covid. So we’re getting numbers that are probably higher than what they would have been historically because we are doing more tests.

“The other component that has probably gone a little bit under the radar is that we have essentially had two-and-a-half years, if not three years, of kids who didn’t have the flu vaccination and didn’t have exposure to influenza in the community. So, they had no immunity at all.

“So that’s going to increase rates, definitely for those who are more vulnerable and susceptible to influenza.”

Dr Cheng said vaccination was the biggest protection against flu, and should be encouraged for children as well as adults. However he conceded the flu season may start in earnest this year before the vaccines are actually available, making preventive health measures like social distancing, isolating when sick and regular hand sanitisation important.

He said GPs could also play a key role in early detection of flu in children, particularly those with other health issues like asthma that could make them more vulnerable to severe complications from the virus. In serious cases hospitalisation is an absolute necessity.

“Often, they need ventilator support in terms of respiratory breathing support, or they have a secondary bacterial pneumonia,” Dr Cheng said.

“In some other kids we see complications of fluid so they get multi-organ failure that spreads into the brain, liver, and kidneys – so then they need rescue therapy to be able to keep them alive.

“Unfortunately, some of these complications do have long-lasting impacts. Even if they do survive the flu component acute phase, there can be long-term impacts which cause disability and significant morbidity for these patients.”

This can include permanent brain and other organ damage that patients never fully recover from, he said.

“These are rare but devastating impacts,” he said.

Australian hospitalisations due to flu impacted those aged under 16 most in 2022, with 2154 hospitalisations per 100,000 population (five to nine years); 1859 hospitalisations per 100,000 population (children under five years); and 1463 hospitalisations per 100,000 population (children aged 10 to 14 years).

In advice to healthcare providers, Professor Kelly called for an increase in the uptake of influenza vaccine among children as a priority this flu season. 

“I am particularly concerned about influenza in children aged six months to less than five years,” he wrote.

“Last year children aged younger than five years had the highest influenza notification rates, with only 32% of the cohort receiving a vaccine. This rate was even lower for First Nations children at 21.5%. Increasing vaccines in children should be a priority.”

The advice recommends annual influenza vaccination should occur from April to provide protection for the peak of the flu season, which is typically June to September in most parts of Australia.

However, Professor Kelly advised that vaccination could occur as soon as the stock was available.

Dr Cheng agreed.

“The timing for people with comorbidities is really important, they need to get on to it as soon as the flu vaccine is available, given that we could have early season again,” he said.

GPs should also be on alert for signs and symptoms of flu and RSV, particularly in children. If they had any doubt about diagnosis they should do a swab, he said.

There were two main things they could to treat children early and potentially keep them from severe complications and/or hospitalisation.

Supportive therapy, particularly for children with asthma or viral-induced wheeze, and ensuring fluids were kept up was also important.

“In some small populations, if started early enough, especially in the risk groups, there are some antivirals, which can help to reduce the duration of symptoms and potentially help to ameliorate some of the severity,” Dr Cheng said.

“But that’s not something that we would use across the board for every child that’s got influenza, but particularly for the for [those at] high risk or patients that are significantly unwell or have a significant comorbidity.”

Children who were struggling to breathe or becoming dehydrated should be referred to hospital, he said.

“In the younger ones, especially infants, for example, if they’re having less than 50%, of what they would normally take in terms of fluids across a 24-hour period, they definitely need to come to hospital for evaluation,” he said.