Chemists are reporting a surge in WA pensioners and people with chronic illnesses such as asthma paying for the flu vaccine rather than waiting for free shots.
Private vaccination clinics say there is strong demand this year, with people paying $10 to $30 to have a flu shot, despite some being eligible for government-funded vaccines next month.
Commonwealth health authorities decided to delay the start of the national immunisation program until April 20 because manufacturers were scrambling to reformulate the planned vaccine to include two strains that had mutated since the composition was decided.
They are trying to avoid what has happened in the northern hemisphere winter, where vaccines performed poorly because of a mismatch with the circulating strains, so were only about 20 per cent effective.
The US Centres for Disease Control and Prevention reported the highest flu hospital admission rates in people aged 65 and over since it started collecting data 10 years ago.
While government stocks will not be ready until next month, there is no shortage of the revised vaccine in the private market.
Clinton Fonceca, clinical director of Nurse Practitioners Clinics Australia, which operates pharmacy-based clinics in Perth and Canning Vale, said he had seen many people aged 65 or over or people with a chronic condition who did not want to wait.
"There's actually a greater need for them to be vaccinated, so it's ironic that they're the ones who have to wait until April 20," Mr Fonceca said.
Reports of a bad flu season in older people overseas had made Australians nervous, he said.
His business supplied about 7000 vaccines last year and he expected it to be about 8500 this year.
He had two nurses booked flat out for the next six weeks.
Mr Fonceca said many more businesses and government departments were offering flu shots to their employees this year.