Communist-run Cuba in a bid to develop its own Covid -19 vaccine has signed an agreement with Iran to transfer the technology for its most advanced coronavirus vaccine candidate and carry out last-stage clinical trials of the shot in the Islamic Republic. The allies are both under fierce U.S. sanctions that exempt medicine yet often put foreign pharmaceutical companies off trading with them and as such they seek to be self-reliant. Both are also strapped for cash. Iran launched human trials of its first domestic COVID-19 vaccine candidate late last month,...