Eligible participants (cohabitants of a recently confirmed COVID19 case) residing in Buenos Aires City will be identified by the Ministry of Health and contacted with the investigators, who will visit them at home and offer to participate. For consenting individuals, a rapid serological test and a nasopharyngeal PCR sample for SARS-CoV-2 will be performed and participants will be then randomized to NTZ or placebo to be taken during 7 days.~SARS-CoV-2 PCR will be repeated on day 14th and the serologic rapid test repeated on day 28th.~Clinical status of participants will be assessed daily by phone. Individuals meeting case definition will be evaluated at home and a PCR will be performed. Those with confirmed COVID19 case will discontinue study medication and followed until symptoms resolution.
The primary objective of this study is to evaluate the efficacy of the drug nitazoxanide 500 mg, administered three times a day, in relation to placebo in preventing the development of COVID-19 in household contacts of patients diagnosed with the disease.