The medicine you're giving your virus isn't working? Let's talk about Antiviral Resistance!

"Oh my God, doctor, this flu medicine doesn't seem to be working right now..." Maybe you've thought that too, right? Or maybe you've heard a friend or relative say that. There are some viral infections, and after a while the medicine given for them becomes ineffective. Today we're going to talk about something called antiviral resistance . This may seem like a complicated word, but it's simple to understand.

What is Antiviral Resistance?

Simply put, antiviral resistance is when a virus stops responding to an antiviral medication that we give it. Think of it like a naughty child who doesn't listen to the medicine. What happens is that the virus changes its nature. Then the medicine that worked before can no longer control the virus, or its effect is greatly reduced. It is very difficult to treat a virus that has evolved to be resistant to this medicine.

This antiviral resistance is part of a larger topic. That is antimicrobial resistance . It means that not only viruses, but also bacteria, parasites, fungi, etc., start to not respond to the drugs designed to treat them. It's like an enemy hiding from a weapon that's trying to kill them and finding new ways to protect itself.

What are antiviral medications? How do they work?

Now you may be wondering, what are these antiviral medications ? These are the types of medications we use to treat diseases and infections caused by certain infectious viruses. Here are a few examples:

• Influenza, or as we commonly call it, the flu.
• Genital herpes.
• Human Immunodeficiency Virus, or HIV .

In some viruses, such as HIV and herpes, these antiviral medications reduce the chance of spreading the infection to others. Also, sometimes if you suspect or know for sure that you have been exposed to a virus, you can take these antiviral medications even if you are not sick.

Okay, now let's see how this medicine works.

When a virus enters our body, it goes inside our healthy cells and uses those cells to make copies of itself, which means more virus particles. We call this the virus replicating . Antiviral medications work by stopping the virus from making copies of itself.

One way these drugs fight viruses is by blocking the virus's ability to enter our cells, or to attach to a cell. Think about it, a virus needs a 'house' to live and infect. That house is our cells. So, if it can't enter that house, the virus can't multiply.

Why do these viruses become resistant to drugs?

This is the most important point. Antiviral drugs reduce the amount of virus in our body, that is, the viral load . However, most of the time the virus does not completely disappear, it remains in the body. So, if you do not take the medicine exactly as prescribed by the doctor, for example, if you miss the medication on some days, or if you stop taking the medicine before the doctor told you to, what happens? The virus starts multiplying again.

As the virus replicates, changes can occur in the virus's genetic makeup . We call this mutating . It's like someone changing their appearance.

If the virus changes too much in that way, the previously used antiviral medicine will not be able to recognize this new virus variety, that is, the virus variant . That is when the virus becomes resistant to the medicine. After that, the medicine will not be able to stop the virus from infecting it.

Sometimes, for no apparent reason, a virus can become unresponsive to drugs that previously worked well. This is called spontaneous resistance . It's as if the virus suddenly decides, "I'm not going to get this drug."

Who is more at risk?

This risk is not the same for everyone. Some people are at higher risk of developing antiviral resistance .

• People with chronic viral infections , such as HIV, genital herpes, hepatitis B, or hepatitis C, are at higher risk because they take antiviral medications for a long time. Remember, when you keep taking the same medication, the virus has more time to adapt to it and find ways to fight it.
• Also, people with compromised immune systems . For example, people with autoimmune diseases , those who have had organ transplants , or those who are receiving cancer treatments such as chemotherapy are at higher risk. Because their bodies' natural ability to fight disease is reduced, the virus can more easily mutate and become resistant to the drugs.

Are drug-resistant viruses contagious?

Yes, unfortunately, this is true. Antiviral-resistant viruses can be transmitted from one person to another. We call this condition transmitted drug resistance . Imagine that someone has already developed a strain of the virus that is resistant to a drug. They can transmit that virus to another person through the exchange of bodily fluids such as semen, saliva, and blood. If you are pregnant, your baby can also be infected with these drug-resistant viruses during childbirth.

The problem with this transmitted resistance is that even if you have never used the antiviral drug in question, the virus can still be resistant to that drug when you are infected. If that happens, your doctor will have to try other antiviral drugs.

How do you identify viruses like this?

If you have an infection like HIV, you can have a blood test to see if you have antiviral resistance . There are two main types:

• Genotypic antiretroviral resistance test (GART): This looks for changes in the HIV genes that make it resistant to drugs. It's like examining the DNA of the virus to see if there are any 'drug-resistant' changes in it.
• Phenotypic antiretroviral resistance test: This measures how the HIV strain responds to different concentrations of antiviral drugs. That is, it looks at how resistant the virus is to each dose of the drug.

Not only this, but organizations like the World Health Organization (WHO) and the Centers for Disease Control (CDC) are also using blood tests to see if viruses like the flu and COVID-19 are becoming resistant to drugs.

How do you treat drug-resistant viruses?

If a virus shows signs of resistance to the medication, your doctor may increase the dose or switch you to a different antiviral medication. However, there are limited approved treatments for some viruses.

Some people with chronic viral infections , such as HIV, that can be life-threatening, take two antiviral medications at the same time. This is called combination therapy . This is done because it is much less likely that a virus will develop resistance to both medications at the same time. Then, one medication can help keep the virus under control.

Can we protect ourselves from this situation?

Yes, the best way to prevent antiviral resistance is to take the medication exactly as prescribed by your doctor, on time, and for the full duration. This is very important.

You can set a reminder on your phone to remind you to take your medicine at the same time every day. Ask your doctor what to do if you miss a dose. You may need to take it as soon as you remember.

Antiviral medications are one of the main tools we have to control potentially life-threatening viral infections. These drugs stop the virus from multiplying and causing symptoms.

So, if you don't take the medicine exactly as your doctor tells you, the virus can become active again and multiply. As it multiplies, the virus can change and the medicine you're taking may not work. If you develop antiviral resistance , your doctor may have to change the medicine or the dosage. So, it's important to follow your doctor's instructions exactly.

A few things to remember in short (Take-Home Message)

Okay, so let's summarize some of the most important points from what we've talked about so that you can remember them more easily:

• Antiviral resistance is when a virus becomes resistant to the drugs given to it.
• The main reason for this is not taking the medication exactly as prescribed by the doctor, for the full duration.
• This risk is higher for people with long-term infections such as HIV, herpes, and hepatitis, and for those with weakened immune systems.
• A drug-resistant virus can be transmitted from one person to another.
• The best way to prevent this is to follow your doctor's instructions exactly. It is essential to take the medication at the right time, in the right dosage, and for the right length of time.
• If you have any questions or doubts about medication, be sure to talk to your doctor.

I hope this information is useful to you. Stay healthy!

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