So the ban on cigarettes is because our government is of the opinion that people who smoke, generally share their cigarette with others, and the transfer of saliva between people is a direct way to spread the virus.
The ban on alcohol is mostly due to the same reason as cigarettes, but also because the consumption of alcohol causes more car accidents, which causes more patients going to hospitals. They are trying to prevent an overflow of patients at hospitals.
Yet, strangely enough, they sent all the doctors from Cuba back home, and there were over 5000 of them in South Africa...