It usually takes years to develop and approve new antiviral drugs because the discovery process is extremely difficult. This 
process involves identifying compounds that target viruses and then testing them for effectiveness and safety. Broad-spectrum
antibiotics can be used to treat many bacterial infections, but the difference is that drugs that are effective against one virus are
rarely effective against other viruses. For example, Remdesivir, which was originally developed to treat hepatitis C, was once
recommended for the treatment of the new coronavirus, but clinical trials have shown that it has limited effect on this 
coronavirus. There are few effective broad-spectrum antiviral drugs because viruses are much more diverse than bacteria, 
including the way they store genetic information (some in the form of DNA, some in the form of RNA). Unlike bacteria, the virus
itself has fewer protein building blocks that can be targeted by drugs.
For a drug to work, it must achieve its goal. This is especially difficult for viruses, because they replicate in human cells by 
hijacking our cellular machinery. The drug needs to enter these infected cells and act on the processes necessary for the 
normal function of the body. Unsurprisingly, this usually leads to collateral damage to human cells, namely side effects.
For viruses outside the cell, it is possible to prevent them from gaining a foothold before they replicate, but it is also very 
difficult. Because the outer shell of the virus is very strong, it can resist the negative impact of the environment on its host. 
Only when the virus reaches the target, its outer shell will decompose or eject substances containing its genetic information.
This process may be a weakness in the life cycle of the virus, but the conditions for controlled release are very specific. 
Although drugs targeting the virus shell sound attractive, some drugs may be toxic to humans.
Although we are only just beginning to understand the life cycle of coronaviruses, there are signs that they can last longer, 
especially in patients with weakened immunity, leading to another problem of the production of more drug-resistant virus strains.
Research to understand how the coronavirus works has made progress in a short period of time, but there are still many 
problems to be solved in the development of antiviral drugs.