Why can’t viruses, such as Covid-19, be cured?
We all know that antibiotics cure bacteria, but our immune system is still largely on its own when it comes to viruses. Antibiotics are no help against the viruses that attack us.
The main reason for this is that viruses are not technically alive! Instead, they depend on our body’s cells in order to reproduce. Viruses have to have a host to reproduce; they can’t survive on their own. So scientists can’t use any agent to fight the virus that would hurt our own cells, where the viruses are hiding out.
Sometimes enzymes on the viruses can be targeted, which is how antiviral drugs work against HIV for example. But even then, the drugs don’t cure the virus, they just keep it under control.
Another reason that viruses are hard to treat is that there are many different types of viruses and they are not related to each other. Different viruses cause a huge range of diseases, such as common colds, chicken pox, SARS, Ebola, hepatitis, and Covid. Some of their genetic codes use RNA, others use DNA; some are surrounded by a protective envelope, others are not.
Bacteria on the other hand are all related to each other, and have common features such as having a cell wall. So it is easier to make antibiotics to fight them.
When a virus infects our body, each cell becomes a virus factory, with the virus taking over and replicating within the cell. Eventually the cell burst, releasing thousands of new viruses which then go on to infect other cells. Our body’s defense is to make antibodies to fight the disease. Our antibodies bind to the virus and then our white blood cells can destroy them.
Scientists have had many more years of experience in treating bacterial infections compared to viral infections. Bacteria were first seen under a microscope in 1683. But viruses were not discovered until 200 years later! We have only had antiviral drugs for the last few decades.
And the antiviral drugs we have do not always help. For example the medication for the Influenza A, Tamiflu, can help shorten the duration of the symptoms, but only if given early. It does not cure the disease. Scientists have made great strides in developing anti-viral medications, such as for hepatitis and HIV, but there is still a long ways in finding effective treatments for most viral infections.
Antibodies (blue) attacking a virus (green):