All Australians should be immunised against pertussis to minimise the impact on all ages, says an expert.
Australia is “probably due” for a pertussis epidemic, but the covid pandemic has made it difficult to predict whether it will happen this year, an expert says.
Speaking at the Immunisation Coalition’s pertussis webinar last week, Melbourne GP Dr Andrew Baird said epidemics typically occurred in Australia every three to four years. The last one happened in 2018-19, “which means we’re probably due for one this year”.
“And two thirds of cases occur in spring or summer and that seems to be worldwide, so we’re entering the season for pertussis,” said Dr Baird, who has a special interest in medical education and rural general practice.
Later in the webinar, Dr Baird was asked whether Australia should be looking at a significant rise in cases this spring and summer, given that an expected surge in cases last spring and summer did not occur.
“The answer is we don’t know,” said Dr Baird. “And we don’t know, because the phenomenon of the pandemic and social distancing … that sort of throws all the statistics up in the air. I don’t think we can really make any definite conclusions.”
He went on to explain that the trend of three to four-yearly epidemics was based on the pre-covid pandemic phase. Lockdowns and covid prevention measures had limited the spread of other respiratory infections such as pertussis and influenza.
Dr Baird said it was difficult to know what the pattern would be from here, and that it would be a “watch this space” scenario.
In the meantime, he said there was much that still needed to be done to lift pertussis vaccination rates in older Australians and adults at risk of complications from the infection.
“Although we may consider that as this is a disease of infants, it’s a disease of all ages,” Dr Baird said.
Although cases in adults are often considered mild, they are still highly contagious and can easily be unknowingly passed on to others. Severe complications, which occur almost exclusively in unvaccinated people, include pneumonia, hypoxic encephalopathy and death.
Dr Baird said research had shown that although the severe morbidity from pertussis was highest in the youngest age group, adults could suffer serious complications with about 10% of those aged over 65 being hospitalised with pertussis and about 8% developing pneumonia.
“So it’s not just a cough and a sniffle,” he said.
“With increasing age there is the phenomenon of immunosuppression … And that lets us down and makes us more vulnerable, particularly when we have comorbidities such as cardiac and respiratory diseases or diabetes in particular.”
He said it was difficult to get an accurate picture of pertussis vaccination rates in older Australians, because records were not kept.
Pertussis vaccination is only free on the NIP for children and pregnant women, meaning all others have to pay for the vaccine – a cost of about $35.
“If we’re looking at older people, we do pretty well with influenza vaccine – eight out of 10 older people get the influenza vaccine, six out of 10 are getting the shingles vaccine, maybe four out of 10 are getting the pneumococcal vaccine, but we really don’t know about what’s happening with pertussis in Australia or overseas,” Dr Baird said.
He said all Australians should ideally have a pertussis vaccine every 10 years after childhood schedules were completed, no matter what their age. And more testing of older people with symptoms would help improve disease surveillance.
“This is the perfect storm,” said Dr Baird.
“It’s surveillance, monitoring and regular vaccination, which would seem to be a good way to go.
“Pertussis occurs in all age groups. It is underreported. Adults with underlying conditions are at increased risk from pertussis. Pertussis can exacerbate other disorders, asthma, COPD and cardiac disease.
“Adults with underlying conditions are at risk of serious complications from pertussis. And booster vaccination may be one of the ways of helping these older people to stay healthy.”
In the meantime, he said health professionals should advocate vaccination strongly to patients, and also to the government through lobby groups, associations and colleges to widen the availability of pertussis vaccine on the NIP.
“I think it’d be a great idea to get it onto the national immunisation program,” Dr Baird said.
“There are countries overseas that have done that, like Italy and there are others. So if others can do it, why can’t we?”