A free whooping cough vaccine for WA parents of young babies has been extended until the end of the year amid concerns the epidemic has not eased.

It is the third time the State Government has extended the program, which was due to end next month, to try to curb the potentially deadly respiratory disease.

There have been 1852 cases in WA this year, compared with 657 at the same time last year and 289 in 2010.

Health Minister Kim Hames encouraged parents, grandparents and household carers of newborns to take advantage of the free vaccine to help prevent the spread of whooping cough, which can cause pneumonia, seizures, permanent disability and death.

It would protect parents and prevent passing the disease to babies.

Toni McCaffery, whose baby daughter Dana died of whooping cough in NSW in 2009, welcomed the decision to extend the vaccination program in WA.