Here is the letter the CDC has posted on their website on therapeutic interventions for Covid-19.
https://www.cdc.gov/coronavirus/2019-ncov/hcp/therapeutic-options.html
It includes the following on HCQ:
ased upon limited in-vitro and anecdotal data, chloroquine or hydroxychloroquine are currently recommended for treatment of hospitalized COVID-19 patients in several countries. Both chloroquine and hydroxychloroquine have known safety profiles with the main concerns being cardiotoxicity (prolonged QT syndrome) with prolonged use in patients with hepatic or renal dysfunction and immunosuppression but have been reportedly well-tolerated in COVID-19 patients. Due to higher in-vitro activity against SARS-CoV-2 and its wider availability in the United States compared with chloroquine, hydroxychloroquine has been administered to hospitalized COVID-19 patients on an uncontrolled basis in multiple countries, including in the United States.
One small study reported that hydroxychloroquine alone or in combination with azithromycin reduced detection of SARS-CoV-2 RNA in upper respiratory tract specimens compared with a non-randomized control group but did not assess clinical benefit
The easy-to-understand theory is that zinc is THE active agent, but zinc alone doesnt enter the cell. Hydroxychloroquine opens a channel for the zinc to enter and do its job. The AZ/zPack keeps lethal bacteria at bay that spread in a weakened immune system.