How Do Viral Infections Work?

Every cell in your body contains a mechanism for manufacturing the proteins and other substances that the cell needs to manufacture during its interphase. Review yesterday’s post for an explanation of interphase. Again, for those who know the details, please excuse the fact that I am simplifying a terribly complex system. This is years of schooling condensed down into a blog post. I can’t be comprehensive here.

There are different types of infections, and a virus is but one of them. What is a virus? It’s a segment of genetic material that enters its target cell, takes over that manufacturing center, and instructs that cell to begin manufacturing copies of the virus. The cell will do that until the interior of the cell is filled with copies of the virus, then the cell bursts open and releases them. Since a virus can’t reproduce by itself, it is not technically alive. Since viruses aren’t alive, antibiotics don’t work on viral infections.

When a person gets a viral infection, there are no magic treatments. The way that these infections have been treated is to suppress symptoms and support the patient until their own immune system can rally and defeat the infection. For example, when you get a cold or the flu, we give you Tylenol for fever, cough medicine to suppress a cough, decongestants, etc.

So how does your immune system work to do this? There are two parts to your immune system: the innate, and the adaptive. The innate system is a number of general responses that fight the infection until the adaptive system can analyze the infection, develop a counter to it, and manufacture that counter. Once the adaptive immune system develops a counter to a particular illness, it will remember that, and you won’t get sick from it again (with some exceptions).

All of those symptoms that you get from an infection (fever, congestion, etc) are caused by your immune system creating what’s called inflammation. The inflammatory response (inflammation) occurs when tissues are injured by infections, trauma, toxins, heat, or any other cause. The damaged cells (that broke open when filled by viruses) release chemicals including histamine, bradykinin, chemokines, interferons, interleukins, lymphokines, tumor necrosis factor, and prostaglandins. Many of these chemicals are referred to as cytokines. When released, they signal the immune system to do its job.

Cytokines are responsible for all sorts of things- runny nose, mucous in the airway, fever, cough, fatigue, all of the symptoms we normally associate with symptoms of being sick. Some infections, and COVID is among them, cause too many cytokines to be released in some people, and the result is caused a cytokine storm. A cytokine storm causes an extreme overreaction of the body to the infection. The immune system actually begins to attack the patient’s own body. This appears to happen to as many as 15% of the patients infected by the original version of SARS-CoV-2, the virus that causes COVID. In some of these patients, and no one yet knows why, the cytokine storm is enough to cause a deadly pneumonia. The only thing that IS known is that having certain preexisting conditions that are already creating inflammation increases the risk of this happening. Things that create inflammation are numerous and varied: diabetes, obesity, asthma, smoking, etc. That’s why there are so many risk factors for COVID being serious.

In these patients, it is cytokines called Interleukins, such as interleukin-6 (1L-6), interleukin-1 (IL-1), interleukin-17 (IL-17), and tumor necrosis factor-alpha (TNF-α) that play a significant role in lung damage in ARDS patients through attacking the tissues of the lungs. A pneumonia develops which requires hospitalization.

Normally, if a patient’s immune system is attacking them, we just give them antihistamines and steroids, which combine to shut down the immune system. That’s what we do to asthmatics, for example. We can’t do that in the presence of an infection, because the immune system is what we are expecting to fight the infection and shutting it down would be a bad idea.

When a patient comes into the emergency room with a suspected infection, there are things that we look for that indicate that the patient has too much inflammation going on. They are called SIRS criteria. (Systemic Inflammatory Response Syndrome). When a patient meets those criteria, there are a set of orders that the nurse implements without consulting the doctor. IV Fluids, chest Xray, drawing blood cultures and other labs, etc. Testing for a host of respiratory viruses is done (Influenza, RSV, COVID, and others). Urine is tested for signs of a UTI. We then give Ofirmev (IV Tylenol) and oxygen as needed. We also give precautionary antibiotics. All of this must be done within 90 minutes of the patient arriving at the ED door, per hospital policy. I average about 55 minutes for getting it all done if I am uninterrupted. It’s a lot of work.

If the patient comes back positive for COVID, they are usually sent home with instructions to return if the symptoms get worse, but if they are one of the unlucky ones who have ARDS, they get admitted. This means that about 90% or so of our COVID patients are discharged home.

The ones who do get admitted are usually fairly sick. I wasn’t here during the early days of COVID in 2020, but I did work in the COVID units in 2021. Many of them were in septic shock, had coagulopathies, and were in pretty bad shape. About one in ten of the patients admitted for COVID died. I really do think that the disease is less lethal than it once was, because in the past two years I can count on the fingers of one hand the patients I have seen die from COVID, with at least two of them having cancer and one of them refusing all treatment because he didn’t believe that COVID was real. Right up until he died, he insisted that we were making it up and purposely making him sick so we could make more money. Just two weeks ago, I had a patient telling me that COVID wasn’t real, and it was all a conspiracy that the doctors were using to make more money. I told him, “OK, well, you have COVID and we are discharging you home. If you feel worse, come back in. Other than that, drink lots of fluids and get some rest. Here are your discharge papers. I hope you get better soon.”

To be honest, that’s all you can say to people who won’t listen to reason.

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As a related note, I want to take a minute to describe and explain Remdesivir.

I already said that viral replication uses the cell’s own manufacturing system to make copies of the virus. The virus in this case is a segment of RNA. How Remdesivir works is that it terminates the RNA transcription that SARS-CoV-2 requires in order to replicate itself.

In late August of 2020, patients who received Remdesivir made a high number of reports of liver and kidney problems. This was due to the government not testing this drug in clinical trials, upending decades of precedent in approving medications. For that reason, many hospitals required patients to sign a statement of informed consent following a full disclosure of the risks and benefits of receiving Remdesivir. At least at my hospital, all patients who received the drug after October of 2020 or so had to sign this consent form.

Now you know.