covid-19 epidemic disease has killed thousands of people all over the world up to now
=>thousands of people.......... have been killed by the COVID-19 epidemic disease all over the world up to now...................................................................................
If you don't rest yourself you really will be ill
=>unless.............you rest yourself, you really will be ill.............................................

1.  Thousands of people have been killed by the COVID-19 epidemic disease all over the world up to now.
2.     Unless you rest yourself, you really will be ill.