- Written or signed informed consent obtained from the parent(s)/ legally acceptable representative(s) of the child. Where parent(s)/ legally acceptable representatives are illiterate, the consent form will be countersigned by an impartial witness. Prior to enrollment of the subject into the post-marketing surveillance, the subject's parents/legally acceptable representatives will be requested to provide information regarding the enrollment of their child in a same/similar study previously. And prior to obtaining informed consent form, the investigator will check whether the subject is eligible for vaccination.