PneuMum is a randomised controlled trial that aims to find out if pneumococcal vaccination for Australian Indigenous mothers, in the last few months of pregnancy or at delivery, can prevent ear disease in infants. Mothers will receive the 23 valent pneumococcal polysaccharide vaccine (23vPPV) either: a) during the third trimester of pregnancy; b) soon after child birth; or c) seven months after child birth (control group). The adult diphtheria, tetanus and acellular pertussis vaccine (dTpa) will be used as the control vaccine for the birth dose.

The study aims to recruit 210 Indigenous women aged 17-39 years who have an uncomplicated pregnancy. Following recruitment, subjects will be randomly assigned to one of the three groups.

Each mother and infant will be followed from pregnancy until the baby is seven months of age. All routinely recommended vaccinations on the standard vaccination schedule will continue to be offered by the subject's vaccine provider in accordance with current clinical practice.

The primary outcome will be prevalence of middle ear disease at seven months of age, defined as middle ear effusion or tympanic membrane perforation or acute otitis media. Pneumatic otoscopy, video-otoscopy and tympanometry will be used in the ear examinations. The primary analyses will be a direct comparison of the proportion of infants in the control group who have nasopharyngeal carriage of one or more vaccine type pneumococci at seven months of age compared to infants in each of the other two groups. A similar comparison of the proportion with middle ear disease will be undertaken between the control group and the respective intervention group.