Canberra's record number of influenza cases this year is due to the flu season starting a month earlier than normal, a leading health expert has said.

The president of the Australian Medical Association ACT, Stephen Robson, said the early start to the season caught many off guard, leading to fewer people receiving influenza vaccinations.

There have been more than 750 reported flu cases in the ACT since July. Credit:Paul Jeffers

"This catches many people by surprise and the people who hold off waiting [for vaccinations] get caught out because last year's vaccinations aren't up to date," he said.

"No doubt the flu season began a lot easier than it had in previous years, and certainly a lot more people have been affected, particularly older people in their 80s and children under 10.