Study aim: The effect of prophylaxis treatment with hydroxychloroquine on the incidence of severe forms of covid-19 virus Design: Randomized controlled trial study; double-blind; parallel groups; on 1000 people; randomization using balanced blocks Settings and conduct: Using balanced blocked randomization people are randomly assigned to one of the two control and intervention groups. The computerization process is done by an epidemiologist and a statistician. For the drug under study, placebo is made by a pharmaceutical company, and participants in the study are blind to receive actual medication. People who measure variables during research are also blind about how people belong to groups. (Two-way blinding) Both intervention and control groups are followed for 10 weeks. Participants/Inclusion and exclusion criteria: Men and women 65-18 years wish to participate in the study have no suspicious symptoms of covid-19 disease Do not have positive test Intervention groups: Intervention Group is500 people and Control Group is 500 people and they are under intervention and follow-up for 10 weeks. Main outcome variables: - COVID-19 Mild type (fever - cough - shortness of breath and positive PCR test) - severe (severe dyspnea - chest pain or constant pressure - decreased level of consciousness - bruising of lips and face and positive PCR test) based on CDC definition