Chief executive of the Burnet Institute Professor Brendan Crabb told a parliamentary inquiry that future responses in how the country deals with Covid should take into account those who have been dealing with long Covid.

Long Covid is defined where patients are still reporting symptoms or contracting new symptoms several months after their initial Covid infection.

“The ones who are suffering, we don’t know the exact numbers … but the numbers are big, and of course they vary widely in severity” Crabb told the inquiry on Monday.

“This is a group who feel left out of the discussion. Australia’s policy is largely based around acute Covid, with trying to protect the vulnerable.”

Monday marks the start of the rollout for the fifth dose of the Covid vaccine.

All adults who have not had a booster or an infection of Covid in the past six months will be eligible for an additional dose protecting them from the virus.

Crabb said an uptake of vaccine intake was needed in order to reduce the severity of Covid among patients, along with reducing the impact of long Covid.

“A fifth dose doesn’t help those who haven’t had their third,” he said.

“The message isn’t getting through that for the first time in the best part of 50 to 70 years, life expectancy is going to decrease in Australia because of Covid, that is how significant is.”

The institute’s head also called for an increase to measures improving air quality in enclosed spaces as a way of lessening the spread of Covid.

Crabb said the messaging surrounding Covid needed to change in order to account for those with long Covid.

“Subliminally at least, it’s very hard (for long Covid) be taken seriously, for employers to take it seriously for example, let alone health professionals,” he said.

“There’s a lot to learn, it’s a mysterious brain fog. It sounds like it’s in your head (but) it’s actually brain damage. We know what brain fog is to a large extent, and we should probably use some words like that.”

Epidemiology chair at Deakin University Professor Catherine Bennett told the committee there was a need for further research to better understand long Covid.

“We do have a concern about our investment in research, the quality, quantity and in particular the coordination of research that’s being done,” she said.

“Long Covid still needs to be well understood, and it affects the ability to generalise results from trials or real-world data analysis of risk factors for long Covid.”

Bennett said research into the area also needed to examine groups that may be more at risk of developing long Covid.

While there is still debate on how health experts will define long Covid, Bennett said broad definitions worked well in early stages, but could be narrowed once more is known.

She said broadly defining long Covid risked including too many overlapping conditions.

“Then you aren’t getting the best benefit of that register or that collected information to understand what’s going on.”