There are several key points for why we don’t have exact medicines for viral diseases:

1. It is challenging to target viruses without endangering our own cells since they use our own cells as a means of replication. Because they take advantage of the distinctions between bacterial and human cells, antibiotics can target certain types of germs. However, since viruses make use of our own biological machinery, developing medications that can eradicate viruses without destroying our own cells is difficult.
2. More quickly than bacteria may adapt and become resistant to antibiotics, viruses can change and develop resistance to antiviral medications. This poses a challenge in the development of widely applicable antiviral medications.
3. Compared to the many more potential targets in bacteria, there are only a small number of distinct viral targets and processes that can be used for the creation of antiviral drugs.
4. Although vaccinations have the potential to prevent viral infections, it is more difficult to create effective treatments for viral illnesses that are already active. Immune system stimulation is how vaccines function, yet certain viruses, such as HIV, can avoid the body’s defenses.
5. It is challenging to create medications that can efficiently target many viruses due to their fast rate of mutation, such as the viruses that cause the common cold. The variety of viruses also makes it difficult to develop antiviral medications that work for everyone.

In summary, the primary reasons we have fewer precise treatments for viral diseases than bacterial, fungal, and protozoal infections are the basic biological distinctions between viruses and other pathogens, as well as the ability of viruses to quickly evolve resistance. The development of antiviral medications that are widely effective is still a challenge for medical research.