Do I need a dengue vaccine for Sri Lanka.

There is absolutely no mandatory Dengue vaccine required to enter Sri Lanka, and the commercially available vaccines are generally only recommended for locals who have previously contracted the disease. The only effective prevention for tourists is rigorous bite avoidance. You must diligently apply strong mosquito repellent containing DEET every morning and evening, wear light colored long clothing after dusk, and ensure your hotel room is heavily air conditioned or features a secure mosquito net over the bed.