I have an update. There has been quite a bit happening around this, and the first publication, a pre-print, has landed a preclinical study from Brazil:
To rapidly respond to an unfolded pandemics, it is pivotal to catalogue preclinical data on the susceptibility of SARS-CoV-2 to clinically approved drugs, as an attempt to trigger clinical trials with promising products (4). We used this approach during ZIKV, YFV, and CHIKV outbreak in Brazil, when we showed the susceptibility of these viruses to SFV (15– 18, 32). SFV and dacaltasvir are considered safe anti-HCV therapy with potential to be used with broader antiviral activity. Here, we demonstrated that SARS-CoV-2 is susceptible to daclatasvir, across different cell types tested, and to SFV, in a cell-dependent manner. In line with their activity against HCV, these drugs impaired SARS-CoV-2 RNA synthesis.
There are also clinical trials in progress, and it seems that the original data from Iran is to be published in a peer-reviewed journal article. So more news is forthcoming.
A personal update: After a delay of two years, largely because of the pandemic, I have finally retired and relocated to New Zealand permanently. Now to work out how to join the NZ health system and get a booster! (I was vaccinated in Japan, but administration was left up to local municipalities, and annoyingly, my city-issued "vaccination passport" is not recognised as valid here.)
There's now a publication in the Iranian trial, dated Feb 2022. It's negative (and this trial is, I think, bigger than all the positive trials combined):
"Between July and October 2020, 1083 patients were randomized to either the sofosbuvir/daclatasvir arm (n = 541) or the placebo arm (n = 542). No significant difference was observed in the primary outcome of hospital discharge within 10 days, which was achieved by 415/541 (77%) in the sofosbuvir/daclatasvir arm and 411/542 (76%) in the placebo arm [risk ratio (RR) 1.01, 95% CI 0.95-1.08, P = 0.734]. In-hospital mortality was 60/541 (11%) in the sofosbuvir/daclatasvir arm versus 55/542 (10%) in the placebo arm (RR 1.09, 95% CI 0.77-1.54, P = 0.615). No differences were observed in time to hospital discharge or time to in-hospital mortality."