About 3,500 people on Rarotonga have received treatment for chlamydia through a Cook Islands government-organised mass treatment programme.
The Ministry of Health dispensed the drug for free through its outpatient clinics during the final two weeks of August.
The programme, which relied on drugs supplied by the Secretariat of the Pacific Community, has been extended to all other 14 islands in the country.
Six of the outer islands have completed the programme, and seven are continuing to distribute the medication.
Before the mass treatment programme, the Cook Islands government estimated about one in four Cook Islanders were infected with chlamydia and as many as two in five people aged between 15 and 19 had the disease.