A comparison between the long-term recovery of COVID-19 and influenza patients suggests persistent symptoms are not unique to a specific virus.

The study by Queensland Health surveyed more than 2000 people diagnosed with the Omicron variant of COVID and 951 with influenza over a 12-week period last year.

Of those infected with Omicron, 21 per cent reported ongoing symptoms at the three month mark and four per cent said they had moderate to severe limitations in everyday life

Among the flu cases, 23 per cent reported ongoing symptoms and four per cent detailed moderate to severe functional limitations.

Vaccination rates in Queensland were high before the widespread circulation of COVID-19, the state's Chief Health Officer John Gerrard said.

"In that context, the study shows a longer-than-expected recovery after a viral illness is not unusual and occurs with other diseases like influenza," he said in a statement on Monday.

"Simply put, long term symptoms are not unique to COVID-19 when applied to Queensland's highly-vaccinated population."

The research comes after health authorities warned of an earlier than usual flu season and a jump in the circulation of COVID cases among Queenslanders.

"While getting vaccinated remains the best protection against COVID-19, the problem of waning immunity in older Queenslanders remains a concern," Dr Gerrard said.

"People over the age of 65 should seek another dose of COVID-19 vaccine if it has been more than six months since previous vaccination or natural infection."

The results will be presented at the European Congress of Clinical Microbiology and Infectious Diseases.

Long COVID symptoms are defined as persisting for more than three months and can include breathlessness, a cough, heart palpitations, headaches and severe fatigue.

More than 90 per cent of Queensland's population had been vaccinated against COVID before the first widespread transmission of the Omicron variant in 2022.