THE Darling Downs has battled through its worse flu season in more than five years with reported cases quadrupling since 2016.
Darling Downs Hospital and Health Service figures show notifications of Influenza A and B have increased from 1559 in 2016 to 4867 this year.
Darling Downs Public Health Unit Director Dr Penny Hutchinson said changes to the virus meant people were more susceptible to falling ill and the flu vaccine was not as affective as in previous years.
"It was a particularly bad flu season,” Dr Hutchinson said.
"I think the main reason is the virus has changed slightly, the influenza virus often changes and sometimes they make very small changes... this may make the vaccination not as affective as in previous years.
Dr Hutchinson said the flu was a "serious disease” which should not be underestimated.
"People assume it's not that serious, it's 'I've just got the flu' but it is a serious disease and people can be very sick from it,” she said.
Dr Hutchinson said while it had been a longer than usual flu season the number of cases was declining and parents need not be concerned about children returning to school.
"We have had a decline in numbers, last week we had 258 notifications which fits but it has gone a little bit longer than usual.
"We have seen a lot of influenza this season in the schools... generally once school holidays are over we see a decline, we don't see a peak after school holidays,” she said.
Update your news preferences and get the latest news delivered to your inbox.