She is considered the patron goddess of fertility and health, particularly protection against smallpox, which is referred to as deviyange ledé ('the divine affliction') in the Sinhala language.
Goddess Pattini is the deification of Kannaki, who is the central character of the Tamil epic the Cilappatikaram of Ilango Adigal, written in South India after the 2nd century.
Historians attribute the introduction of goddess Pattini to the island to Gajabahu I, a Sinhalese king who ruled Sri Lanka from 113-135.
As per some historians, the Cilappatikaram mentions Gajabahu's presence at the consecration of a temple to Kannagi (identified as Pattini in this case) by the Chera king Cenkuttuvan.
[1] Pattini is honoured in annual fertility rites such as Sinhalese people believe that diseases like chickenpox and measles are punishments by God for frailty.