Older Australians are being warned to not double up on flu shots amid fears the over-65s vaccine won't protect them against a deadly strain of the virus.
The calls from health authorities follow reports of older people rushing out to get a second flu shot, concerned that the federal government's free vaccine for over 65s doesn't include the Brisbane B strain.
Originating in Brisbane, the virus was named the deadliest in the world by the World Health Organisation last year and is included in this year's four-strain vaccination designed for those under 65, along with two A strains and another B strain.
Over-65s have been receiving a three-strain trivalent vaccination that doesn't cover Brisbane B.
During last year's brutal flu season, 90 per cent of the 1100 influenza-associated deaths recorded were in the elderly.
But health experts say there is no need for seniors to double up on jabs.
Australian Medical Association president Tony Bartone said the over-65s jab remains the best protection for older people.
"The advice of experts such as the peak national clinical advisory group - the Australian Technical Advisory Group on Immunisation - is quite clear and specific," Dr Bartone said, "and there is no data suggesting people over 65 need to take both vaccines."
Dr Bartone said as well being unnecessary, doubling up could threaten vaccine supply.
"There have been multiple reports of vaccines running out," he said. "We really need to be very judicious in our use of resources and make sure we have adequate supplies."
The unprecedented demand for the seasonal vaccines has almost exhausted current flu vaccines available through the National Immunisation Program following concerted state and national campaigns to lift flu immunisation rates.
Dr Bartone said the timing of the immunisation rollout was critical, with the peak flu season expected between July and September. Any shortfall in available vaccines could delay the process.
"Anything which interferes with this timely vaccination program is singularly unhelpful," he said. "We have an opportunity and often don't get a second bite of the cherry to immunise the community."
Australian Chief Medical Officer, Professor Brendan Murphy, described getting another jab that includes the Brisbane B virus as "pointless". He said it would not give any better protection.
"Unfortunately there seems to have been confusion in the minds of some people in Queensland due to the name of the virus," Dr Murphy said. "It has nothing to do with what is happening in Brisbane but was named in 2008 when the virus was first identified."
Australian Chief Medical Officer Professor Brendan Murphy
He said the decision to leave the Brisbane B virus out of the over-65s vaccine was "very deliberate".
"The super-powerful vaccine for the over-65s comes only in three strains and it doesn't really matter as most elderly people only get the A strain and it is unlikely the Brisbane strain - the least important of all the strains - will be a particular problem in the Oceania region."
Dr Murphy said if it was, it was more likely to be in younger people.
Queensland Health's medical director of the immunisation program, Dr Alun Richards, echoed the AMA's reassurances, saying global experts recommended the trivalent vaccine for over-65s for a number of reasons.
He said older people do not respond as well to standard flu vaccine as the immune system response to flu vaccine decreases with age.
"The enhanced vaccine is designed specifically to increase the immune system's response to vaccine, especially against influenza A (H3N2) strain, which is more common and severe in people aged 65 and older," he said.
Dr Richards said the enhanced vaccine provides a stronger defence against two A strains and one B strain.
"Australian surveillance data shows those aged 65 and older are affected more by A strains that are circulating in the community, than they are by B strains," he said.
"Research also shows that older people tend to have a level of immunity to B strains because of exposure to these strains in previous seasons.
"Although the enhanced vaccine contains one less B strain virus, the benefits of better and broader protection against the strains included will outweigh any potential loss of protection against the missing alternative B strain virus."
Dr Richards said while Queensland Health does not recommend obtaining the two vaccines, there were no serious safety concerns for anyone who has already received both.
What you need to know
The National Immunisation Program provides free flu vaccines for the elderly, as well as other high-risk groups including pregnant women, people with chronic diseases and Indigenous Australians.
There are two free vaccines for over-65s which work in different ways - FluZone High Dose, a high dose version; and Fluad, a "super-boosting" jab with an extra ingredient to boost its effectiveness. Both contain three strains.
Anyone aged 65 and over who hasn't received their flu vaccination is advised to book an appointment with their GP.
Dr Richards said over-65s are at greater risk of serious complications from influenza infection, and have the highest influenza-associated death rates each year.
This story first appeared on www.thesenior.com.au