HALIFAX -- CTV News Atlantic’s Heidi Petracek interviewed Dr. Lisa Barrett, clinician scientist and infectious disease physician at the Senescence, Aging, Infection and Immunity Laboratory at Dalhousie University and the Nova Scotia Health Authority, for a better understanding of COVID-19 and how it affects patients.

Here is that conversation:

In Nova Scotia, we have two cases where two men, around the same age, are being affected by COVID-19 in very different ways. One is in critical condition in intensive care. The other has been recovering well at home. Why is there such a difference?

Dr. Lisa Barrett: Many times, we have one particular virus or bacteria that causes infections, and what you’re referring to is what we call the “clinical spectrum of disease.” The same infection in one human might look very mild, not cause too much damage in the lungs, or wherever the infection is.

However, in another individual who seems to be the same age, with similar sort of health status before they get the infection, they would actually have a different response that might be quite a bit worse. Sometimes we know the reason why, and sometimes we don’t.

In this case, with COVID-19, it’s caused by a virus that we’ve known about for about three months. So three months is not a lot of time for us to understand how and why the virus causes trouble with your lungs.

That’s what we call “prognosis” – how do we predict what’s going to happen to someone?

The take-home message is: We’re not sure why some people get sick and some people don’t. We do know that people with lung problems before they get sick, as well as people with diabetes, or problems with their immune system … they may get more severe disease or may be more likely to get infected than some other people.

What is some of the research that is going on in Nova Scotia right now?

Dr. Lisa Barrett: Much of that research is going on around the world, but also here in Nova Scotia with Dalhousie University and the Nova Scotia Health Authority.

We’re just about to start doing studies to do what we call “surveillance” – [which is] when we look for the virus and understand what that person [who has it] is different of the same than other people. That’s a big study that’s going on out of the NSHA, Dalhousie, the Canadian Centre for Vaccinology with Dr. Shelly MacNeil, and we’re all a part of that.

We’re also studying whether some of the medications that are available on the market already may be useful in treating this disease, and also in predicting who would respond. We need to study these things by taking blood from people who are ill, or just before they’re ill. It’s really important that we do that work.

 What’s an example of a medication that already exists that is being investigated in terms of whether it could help in these cases?

Dr. Lisa Barrett: There are many trials … around the world that are going on. These trials include medications for HIV – there are some medications that inhibit the HIV virus, and now they’re being tried in the context of [COVID-19] to see if they work.

There’s a medication that’s used to dampen down your immune system in other inflammatory or rheumatology conditions called plaquenil, that one is being used as well. Some people may know it as hydroxychloroquine (not the malaria drug, but related to it). That one is also being used [in trials] to see, not if you can inhibit the virus so much, as to inhibit the inflammation that it causes. It may do a little bit of both, we don’t know.

And then the other medications that we’re going to be trying as well as some other people in the world are ones that dampen down your immune system. That’s important because the reason we think people get very sick with this virus and have difficulty breathing is that their lungs become very inflamed. And when their lungs are inflamed and damaged, it’s not possible to breathe well. That’s why they end up in an ICU and some people die.

Reducing your immune response sounds like a funny thing to do when you’ve got an infection, but at this point when people start to get sick, it may be very important to ramp down the inflammation, and allow your body to just “cool off” a little bit, instead of causing lung damage.

In the end, if a person doesn’t know how sick they would get, that must really add to the importance of staying home, because you just don’t know at this point.

Dr. Lisa Barrett: We definitely know that people with poor immune systems, underlying lung disease, maybe diabetes, maybe some other heart problems, are more at risk to get severe disease and end up in hospital. But there’s a lot of people in the hospital in the U.S. for example, who don’t have those problems. They’re between the ages of 25 and 40, so it’s not just older people.

Because we can’t predict exactly who is going to get sick, and maybe not recover, it is imperative for people’s own personal health … to stay at home right now, when you can, and that means almost always unless you’ve got to go out to be an essential service worker.

Wash your hands a lot, don’t touch your face, please, and disinfect the surfaces that are in your home. It is so important, and it can change the course of this whole epidemic, not just for the population but for each person.

We can’t predict who gets sick. You need to not get this virus. That’s not meant to panic people. It’s just meant to say, you’ve got an opportunity here. Use it to avoid the virus, as opposed to worrying a lot about who exactly is going to get sick or not.