The Chloroquine for Influenza Prevention Trial

Inclusion Criteria: * Age 18 -65 * Have the ability to provide informed consent * If a woman of child-bearing potential, willing to use contraception for the period of the trial Exclusion Criteria: * Acute influenza-like illness at screening * History of psoriasis, porphyria cutanea tarda, epilepsy, myasthenia gravis, myopathy of any cause, cardiac arrhythmias, or serious hepatic or renal disease * Pregnancy or breast feeding * Current use of medication with known serious hepatotoxic effects * Current use of medication with known serious interaction with CQ: amiodarone, anticonvulsants, ciclosporin, digoxin, mefloquine, moxifloxacin * Current severe depression (as indicated by current use of antidepressant medication) * Known serious retinal disease * Current or recent (within the past 30 days) participation in any other clinical intervention trial. * Known G6PD deficiency * Vaccination for influenza (seasonal or H1N1 strain) within the 3 months prior to screening