New research supports prompt treatment as Australia experiences a late-season influenza surge.
Antiviral therapy initiated within 48 hours of influenza symptom onset was associated with 81% lower odds of related hospitalisation in kids, a new study has reported.
The findings add to evidence that early antiviral treatment can reduce severe influenza outcomes in children during a time when Australia is experiencing a late flu surge and increased hospitalisations.
This multicentre, age- and season-matched, case-control study included 1492 paediatric outpatients with laboratory-confirmed influenza at major hospitals in northern Taiwan between 2020 and 2023. The cohort comprised 354 children who were subsequently hospitalised and 1138 nonhospitalised controls. The mean age was 7.1 years, 44% of patients were identified as female, and 86.7% of cases were influenza A.
Among the cohort, the 1206 children (80.8%) who received antiviral therapy within 48 hours of symptom onset had significantly lower rates of hospitalisation (16.1% vs 55.9%) and influenza-related severe illnesses (0.7% vs 3.1%) than those who received late or no antiviral therapy.
Early antiviral treatment was associated with 81% lower odds of hospitalisation across the cohort overall, with a similar association observed when analysed by age (adjusted odds ratio 0.19 in children five years or younger, aOR 0.15 in those older than five).
The two agents used were oseltamivir (Tamiflu, Roche Products), which is TGA approved for children from one year old and PBS-funded, and zanamivir (Relenza, GlaxoSmithKline) which is not approved for children under five years of age and not included in the PBS. The results were consistent across both antivirals.
Despite the availability of influenza antivirals, they are not widely prescribed in Australia. Associate Professor Paul Griffin, Director of Infectious Diseases at Mater Health Services in Brisbane, told Allergy & Respiratory Republic that practices should consider ways to streamline access to antivirals for some patients during this current flu surge.
“I think there’s a few important points [as to why antivirals aren’t widely used]. I think one of them is a bit of a lack of knowledge and a perception that they don’t do very much. There certainly has been some resistance, depending on some flu types, so we know that resistance is a little bit of an issue, and we know there’s been some studies that have suggested perhaps there’s not as big a benefit in some populations as we thought,” he said.
As a medication class that can only be prescribed by doctors, the biggest accessibility issue is the logistics of going through the diagnostic process and initiating antivirals within the period when they are most effective.
“If you start them late, they’re not going to do as much. And it’s logistically more challenging to confirm the diagnosis of flu and get back in to see your GP in time to get that prescription,” said Professor Griffin.
“You’ve got to be in contact with your GP, get a referral, go and have the test done, confirm the diagnosis, and then get back in touch with someone to prescribe it. To do that in the first 72 hours is actually quite challenging if there’s not been some work ahead of time to prepare.
“[However,] as the study highlights, if you do get them started early in the right patients, they’re very likely to confer a benefit, and I think it is important that people do understand they still have a role.
“I think some people have kind of forgotten a little bit about the importance of them and the impact they can have, and also some people have questioned how effective they are [and] whether they’re worthwhile. If we remind people [with] studies such as this one that if we do choose our patients right and we do get them in early, that there is still likely to be some benefit.”
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He suggested incorporating strategies into clinical practice for high-risk patients to access testing and antivirals more easily during periods of increased transmission like we’re currently experiencing.
“Whether there’s a way they can get a request form without needing to book a full appointment, for example, for the testing. Whether there’s a way [patients] can know how they can just be sent a prescription if the test is positive, rather than having to once again await a full appointment,” he explained.
“I think that’s certainly something to consider because we don’t want particularly high-risk people or people who are more unwell to miss out on the opportunity of having something that might prevent them getting worse.”
He said that rapid antigen tests that can be done at home do have some benefits and a positive result can streamline the process of initiating antivirals, but he highlighted their reduced sensitivity.
“Their sensitivity is far less than laboratory-based tests so… you can believe the positives but be sceptical about the negatives. If someone has a flu-like illness at the moment, has a negative rapid antigen test, it probably still is the flu. And we know, for example, a lot of those common rapid antigen tests sensitivity for flu B can be in the sort of 30 to 40% range, which means it’ll miss more than half,” he said.
“The other issue is a lot of people are pulling out rapid antigen tests that they might have bought during covid that have expired, and they’re probably not going to work anyway.”
This latest study also noted lower odds of hospitalisation associated with influenza vaccination (aOR 0.62) and Professor Griffin told ARR that it’s not too late to encourage flu jabs.
“Obviously, it’s much later than we would have liked ideally, but not too late that you still might not get some benefit. A lot of people are talking about why we are seeing this [surge in flu cases] now, and undoubtedly part of it is the fact that our vaccination uptake remains poor,” he said.
“It’s been an interesting flu season, and what we want to do is be a bit more proactive next year. It’d be great if we could use some of the commentary at the moment to build a platform upon which we get a boost in vaccine rates next year.”
