The current standard of care is observation and quarantine after exposure to COVID-19. There is no approved treatment or prophylaxis for COVID-19.~As of March 6, 2020, the CDC estimates that the transmission of SARS-CoV2 after a U.S. household close contract is 10.5% (95%CI, 2.9 to 31.4%). Among all close contacts, the SARS-CoV2 transmission rate is estimated at 0.45% (95%CI, 0.12 to 1.6%) by the CDC. These estimates are based on monitoring of travel-associated COVID19 cases. Conversely, in a setting with community transmission, the secondary attack rate in China was 35% (95%CI, 27-44%) based on 48 transmissions among 137 persons in 9 index patients.~Chloroquine or Hydroxychloroquine may have antiviral effects against SARS-COV2 which may prevent COVID-19 disease or reduce disease severity. It is not known at what dosing hydroxychloroquine may be effective for pre-exposure prophylaxis.
Objective: To determine if pre-exposure prophylaxis with hydroxychloroquine is effective for the prevention of COVID-19 disease.