Researchers say whooping cough bacteria could develop superbug strains

UNSW researchers say the whooping cough bacteria are becoming smarter at colonising and feeding off unwitting hosts.

The current vaccine, widely used since 2000, targets three antigens in the bacteria of the highly contagious respiratory disease, which can be fatal to infants.

All babies under six months old - in particular newborns not protected by maternal immunisation - are at risk of catching the disease because they are either too young to be vaccinated or have not yet completed the three-dose primary vaccine course.

Australia's whooping cough epidemic from 2008-2012 saw more than 140,000 cases and revealed the rise of evolving strains able to evade vaccine-generated immunity.

In a series of UNSW studies, researchers showed that the evolving strains made additional changes to better survive in their host, regardless of that person's vaccination status. They also identified new antigens as potential vaccine targets.

First author and microbiologist Dr Laurence Luu, who led the research team with Professor Ruiting Lan, said whooping cough's ability to adapt to vaccines and survive in humans could be the answer to its surprise resurgence despite Australia's high vaccination rates.

"Put simply, the bacteria that cause whooping cough are becoming better at hiding and better at feeding. They're morphing into a superbug," Dr Luu said.

Therefore it was possible for a vaccinated person to contract the disease without symptoms materialising.

"Another issue with the vaccine is that immunity wanes quickly, so we do need a new vaccine that can better protect against the evolving strains, stop the transmission of the disease and provide longer lasting immunity," Dr Luu said.

While he would like to see a new vaccine developed and introduced in the next five to 10 years, Professor Lan said the research team's discovery did not render Australia's whooping cough vaccine redundant.

"It is critical that people are vaccinated to prevent the spread of whooping cough - the current vaccine is still effective for protecting against the disease," he said.

The number of whooping cough cases has increased over the past decade, however the researchers said the number was nowhere near as high as it was before the introduction of vaccines.

They emphasised that vaccination is especially important for children, people who are in contact with children and pregnant women, who need the vaccine to produce antibodies to protect their newborns from developing whooping cough in the first few weeks of life.

As well as babies under six months, others most at risk of catching the disease are the elderly, people living with someone who has whooping cough and people who have not had a booster in the past 10 years.

Whooping cough is characterised by a "whooping" sound and sufferers find it difficult to breathe.

It is more common during spring and spreads when an infected person coughs or sneezes and other people breathe in the bacteria.

The latest UNSW study was published in Vaccine.

The Department of Health recommends whooping cough vaccination for:

CHILDREN aged 2 months, 4 months, 6 months, 18 months, four years, and between 10 and 15 years (at school), at no cost under the National Immunisation Program (NIP);

PREGNANT women in the third trimester, ideally between weeks 20 and 32 of every pregnancy, at no cost through the NIP;

HEALTHCARE workers, if they have not had a whooping cough vaccine in the past 10 years;

PEOPLE working in early childhood education and care, if they haven't had a whooping cough vaccine in the past 10 years;

ADULT household contacts and carers of babies under 6 months old;

PEOPLE who are travelling overseas, if they haven't had a whooping cough vaccine in the past 10 years.

ADULTS of any age who need a tetanus, diphtheria or polio dose (you can get a combination vaccine that includes whooping cough to increase protection).

PEOPLE aged 50, at the same time as they get their recommended tetanus and diphtheria vaccine.

PEOPLE aged 65 or over, if they have not had a whooping cough vaccine in the past 10 years.