Viruses are not alive, so they cannot die. However, the protein coat can be denatured (like egg white which is permanently changed in a heated frying pan), rendering it inactive. Viruses enter a cell and take over the replication machinery to make more copies of themselves, in addition to certain proteins. They then pass on to other cells, repeating the process.

 

One big problem with viruses is that they mutate at a very quick pace. RNA viruses (which corona viruses are), replicate without proofreading activity (like DNA viruses carry out), and as a result, errors in genetic coding occur. It is these errors that allow RNA viruses, such as influenza and HIV, to mutate rapidly, and make it difficult for vaccines and natural immunities to keep up. When you look at all the different viruses associated with people and many different animals, there is a lot of room for quick change in the viral world. That is why new influenza vaccines are made each year. The top 3-4 most likely choices of flu's coming out of Asia, are made into a vaccine which is offered to the public, to prevent the flu. Unfortunately, the guess is not always correct, and vaccines are sometimes ridiculously ineffective (like 80%). I am not a big fan of flu vaccines, but for different reasons (more later on this).