A free vaccine will be introduced from April next year to protect Australian teenagers against four strains of the meningococcal infection.

Through the National Immunisation Program, the combined vaccine for the A, C, W and Y strains will be available at no extra cost to Australians aged 14 to 19.

With the deadly infection killing 28 Australians last year, over a million teenagers are expected to receive the free vaccine over the next four years.