<qa>  How many arms will the trial enrol 900 girls in?The trial will enrol 900 girls who are resident in Mwanza into an un-blinded, individually-randomised trial with 6 arms. Arm A will comprise participants randomised to receive 3 doses of the 2-valent vaccine, Arm B those randomised to receive 2 doses of the 2-valent vaccine and Arm C those randomised to receive 1 dose of the 2-valent vaccine. Arms D, E and F will be those participants randomised to receive 3, 2 or 1 dose of the 9-valent vaccine, respectively. 