The study aims to determine whether the early administration of adjuvant corticosteroids in addition to high dose oral Co-trimoxazole reduces mortality amongst infants aged 2-6 months with vertically acquired HIV and clinically diagnosed Pneumocystis jiroveci pneumonia. Infants will be randomized to receive either a steroid regime of oral prednisolone at 2 mg/kg for 7 days, then 1 mg/kg for 7 days, then 0.5mg/kg for 7 days for a total of 21 days or placebo.