Infection occurs when a virus enters into the body's cells and replicates itself.
You can think of the virus as an enemy, and the cells - a shield.
And vaccines are designed to train the body to fight and defeat that particular enemy.
They intentionally expose the body to an inactive form of the virus or pieces of one, which triggers the immune system and produces antibodies.
Antibodies are like a weapon, that will offer protection when the body encounters the real thing.
But a vaccine's effectiveness can wane over time, and there are some people who cannot get them due to medical reasons.
That's why treatments are needed.
One way to produce them is by using antibodies.
The Y-shaped proteins bind to the virus' spike proteins,.. blocking them from piercing into the body's cells.
If vaccines help the body develop the weapon on its own an antibody treatment is basically injecting it directly into the body.
There's also a treatment that directly targets the virus antiviral drugs.
The chemical compound makes it difficult for the virus to survive, during its replication cycle.
The virus uses certain enzymes of the host cells to replicate itself.
And, an antiviral drug can be made to affect those particular enzymes.
Because antibody treatments block the virus from penetrating into new cells and inhibits its spread, they prevent patients from becoming severely ill.
The ones made by U.S. drugmaker Regeneron or South Korea's Celltrion use this method.
Meanwhile, antiviral drugs like the pills from both Merck and Pfizer can target the virus in already infected cells and help relieve the symptoms of severely ill patients.
The two types of treatments complement each other. but both have their pros and cons.
"Antibodies are protein,that can be derived from an infected person. So the initial development is relatively easy but it's very expensive to mass produce them in the lab.
Antivirals on the other hand are just chemicals. They're harder to initially develop, but are much easier and cheaper to mass produce and store."
Experts hope these drugs could help us treat COVID-19, in a similar way to how we treat flu using over-the-counter medicines like Tamiflu.
Lee Kyung-eun, Arirang News.