Inclusion Criteria:  This study will include volunteers household contact of COVID 19 confirmed cases who attend the triage clinic in the participating centers. Included persons should be > 18 years old and below 65 years, without any contraindications for Mefloquine usage.  Exclusion Criteria:  • People with history of previous confirmed COVID-19 infection.  Pregnant and lactating females. People with neuropsychiatric disorders: myasthenia gravis, epilepsy, psychotic disorder, schizophrenia, repeated episodes of anxiety, depression. People with liver cirrhosis or raised liver enzymes. People with arrhythmias or prolonged QT interval on EKG. People with a history of Quinidine-Quinine analogs allergy.