Call to deploy antivirals in flu fight

While vaccination might be too late for many, health experts say antivirals should be used as a second line of defence.

---

With just a third of Australians vaccinated against influenza, health experts have called for reinforcements in the fight against this year’s “severe” flu season.

While vaccination remains the first line of defence against the flu, they say low vaccination rates in Australia mean the second line of defence – antivirals – should be deployed wherever possible.

According to immunisation data released by the Department of Health and Aged Care this week, 8.8 million Australians have received a flu vaccine this year. Last year that number reached almost 10.7 million. The bulk of flu vaccines (about 5.5 million) have been provided this year by GPs.

Infectious diseases expert and Immunisation Coalition board member, Professor Robert Booy, said antivirals such as oseltamivir (Tamiflu, Roche) had an important role to play in reducing the severity of the illness, potentially reducing the risk of a secondary bacterial infection, hospitalisation and death.

Reducing the viral load of a patient also helped to reduce transmission, he said. And he said waiting for a laboratory to confirm the diagnosis was not necessary, given the fact that the antivirals must be started within 48 hours of symptom onset to be effective.

“The flu has been quite severe this season and therefore it is truly worth catching it early,” he said.

“If it’s July and flu is clearly already predominant. You can give an antiviral without necessarily having to do a PCR test, which takes time to confirm.”

According to the National Communicable Disease Surveillance Dashboard, there have been 175,582 cases of influenza in Australia this year (as of 26 July).

The state/territory breakdown shows NSW has had the bulk of cases (63,542), followed by Queensland (53,374), Victoria (26,807), Western Australia (15,228), South Australia (10,607), Tasmania (2282), the ACT (1958) and the Northern Territory (1784).

More females (90,703) have had laboratory confirmed influenza so far this year than males (84,611). And more than half of the cases nationally have been in people aged from birth to 19 years (89,389). At the opposite end of the age spectrum (65 years and older), the case tally sits at 13,814.

The age group that has been hardest hit overall has been those aged five-to-nine, with a recorded 34,500 cases.

Professor Booy said that while the antivirals were not PBS-listed, they had an important role to play in minimising the serious effects of the flu.

“They are TGA-approved for their safety and effectiveness, so if you’re going to prescribe antivirals, this month is the time when it’s most relevant. By August, September, it may well be too late.

“While flu is peaking, or at very high levels, you can reasonably assume that someone with the symptoms of the flu actually has the flu and prescribe [antivirals] so that they get rapid antiviral treatment, on the same day if at all possible.”

There have been questions raised over the years about the efficacy of antivirals for flu, but in Australia they are approved by the TGA for anyone aged from two weeks old.

“The CDC in the United States cites evidence that Tamiflu use as an antiviral can reduce the length of illness can help to reduce hospitalisation and secondary bacterial infection,” said Professor Booy.

“This is an antiviral that for which there is some evidence that prevent secondary bacterial infections that prevents hospitalisation and may prevent fatal complication.”

Associate Professor Paul Griffin, director of infectious diseases at Mater Health Services in Brisbane, said he believed antivirals were being underutilised.

“I think we’ve lost sight a little bit of the fact that we do have antivirals for the flu,” the Associate Professor of Medicine at the University of Queensland told TMR.

“I think that’s multifactorial. I think the focus obviously has been on covid, and there’s been a little bit of variability of efficacy reported with flu antivirals over the years,” he said.

“They are a really important part of our strategy, particularly given our vaccine rates are low and the burden of influenza that we’ve seen recently.

Professor Griffin said people with severe disease or at high risk of developing severe disease were the main groups best suited for antivirals.

“They actually can be used fairly broadly, but how well they work is it is very much dependent on how quickly they get started,” he said.

Professor Booy said he believed more effort should go into improving vaccination rates earlier in the year before the flu season starts, although there was still time this year for people to take advantage of a flu vaccine.

“For those who haven’t had flu and have got the opportunity to get vaccinated, that group may well benefit from vaccination,” he said.

“But honestly, if we’re going to push vaccination, we should be doing it in April, May and June, not in July when it’s already peaking.”

Professor Bruce Thompson, head of the School of Health Sciences at the University of Melbourne, said preventive health measures like masks and social distancing were also important in keeping flu in check.

And he said while the focus had been on flu in recent weeks, people should not dismiss the risks of covid.

“It hasn’t gone away, it’s killing lots of people,” he said.

According to latest data from Covid Live, 22,157 Australians have died from covid since the start of the pandemic. In the seven days to 21 July there were 6251 new cases in Australia and 91 deaths.