Night Runner by Max Turner
Zack Thomson is 15 years old and lives in the pschychiatric ward of a hospital in Barrie. He's not mentally disturbed although he certainly has some unusual problems. For instance, he has a severe allergy to sunlight which means that he can only go outside at night. And he can't tolerate any solid food - he only drinks a frothy red beverage that Nurse Ophelia whips up for him every night.
His monotonous life, enlivened only by visits from his friend Charlie, changes abruptly when an elderly man on a motorcycle crashes into the lounge room of the ward. From him, Zack learns that his condition is vampirism, and further, that another vampire is out to kill him.
Zack bolts from the hospital, and with an unknown person (thing?) on his heels ends up at Charlie's family cottage in the Muskokas. Here, his would-be killer is still on his heels, but at least he gets to do some late-night partying with other teens and a tiny bit of a romance before the action heats up again for him.
Short chapters, lots of action, humorous dialogue make this a fast and absorbing read even for the reluctant reader.