The 18-year-old was last seen at her Damien Court home at around 10:00 am on Saturday, February 29.
She left home to attend a public event in Mordialloc.
Gallo was driving a black Holden Astra, registration XGH 389.
Police and family have concerns for the teen as her disappearance is out of character.
She is described as of Caucasian appearance, 162 centimetres tall, medium build with long brown curly hair.
Investigators have released an image of Gallo in the hope someone recognises her and can provide information regarding her current whereabouts.
Anyone with information about Jaina is urged to contact Fawkner Police Station on (03) 9355 6000.
