COVID 19 Questions Answered

July 24, 2020
Dr. Nadig
Dr. Nadig

The head of MUSC’s COVID-19 antibody testing task force recently answered questions about immunity, the need for plasma donations and progress toward a vaccine.

MUSC transplant surgeon Satish Nadig, M.D., D. Phil., is medical director of the Center for Cellular Therapy and a researcher who studies immunology. In fall of 2019 he was part of a team that earned a patent for using nanoparticles to deliver anti-rejection drugs directly to a transplanted organ.

In April 2020, Nadig was tasked with building a team to start working on a new project: an in-house COVID-19 antibody test. That test has since been offered to all MUSC employees and first responders in the Charleston, Florence and Lancaster areas, and to anyone who gives blood through The BloodConnection.

Nadig answered the following questions during a video chat with the MUSC Office of Development and Alumni Affairs.

What have you learned about immunity from antibody testing?

That's a great question. Those are ongoing things. What we don't know is, when somebody has antibodies, how long are they immune for? Are they actively immune to it? We don't know those answers. We can assume that they have antibodies to SARS coV-2 and that if they just had the disease and they developed antibodies, it's probably to COVID and that they have confirmed some sort of immunity.

Some of the research we're doing is looking at a combination of cell mediated immunity and antibody immunity. So, your T cells and antibodies, and how they work together for you to be immune against COVID. But what we do don't know is how long that's for. Coronavirus immunity lasts on average about seven to nine months. And whether this acts the same way, we haven't had the disease around long enough to know.

We think that yes, it does confirm some amount of immunity. How much and how long – we're still in the process of figuring out. There's a lot of research around campus and around the country – around the world, frankly – to try to figure that out.

What we do know is that there is a type of antibody called neutralizing antibody. Those antibodies are the ones that actually neutralize the virus. Just because you have antibodies doesn't mean that you have that neutralizing antibody. We’ve bought kits to do neutralizing antibody testing on those who've had positive antibodies.

So, hopefully, we'll have some of that information as we move forward. There's a study out of China that suggests that people who are asymptomatic don’t keep their antibodies as long and don't have as many neutralizing antibodies.

So, these asymptomatic carriers can actually shed viral antigen or viral proteins for longer and they don't actually have antibodies for as long a period of time. So, they may not be as immune.

So, does that mean that people can catch the virus multiple times?

That's potentially the case. And does that mean that just because you're asymptomatic you can't spread it? That's a fallacy. You can spread it. And so that's why it's important for everybody to wear masks and physically distance, whether you're symptomatic or not.

Are certain blood types less likely to test positive for COVID-19?

It's not necessarily less likely to test positive, but less likely to get sick from the disease. But there's some truth to testing positive and it’s the A blood type.

So, that's also some data that has come out of our research from the Blood Connection, but also pretty well established out of mostly China is where a lot of people are doing these types of research.

What do you think of saliva testing for COVID-19 antibodies?

So that's like a game changer, right – a lot easier than giving blood. Clemson has been working on that.

Do you think we need another shut down to slow the rate of COVID-19 infections in South Carolina?

I get asked that question, not too infrequently. What should we do with schools and what should we do with work?

My personal opinion is that it's not a black or white thing. It's not on or off. I think that can hurt us actually. If we go – everything shut down, everything open up, everything shut down again – I think it economically cripples us too. So, I think we need to be fluid with this and watch the waves of prevalence not only in our state but within our own counties to figure out how to open in a more fluid manner. 

How important is plasma donation right now?

Well, I'll give you an example of how important plasma donation is. I had a 15-year-old transplant patient who needed convalescent plasma. We had to have him in a queue, because we didn't have enough plasma. That should answer that question.

He ended up getting it, but he had to wait. What, if he was really, really sick? What if he was on a ventilator? That would have been tough. I feel like we have enough people that can do enough good that can donate plasma that we shouldn't have to be in that that situation.

How close are we to a vaccine?

I think a couple of weeks ago there were about 125 potential vaccines in trials. The one that people think is the closest is the one out of Oxford that they say is coming this fall. They're already in phase II, but I think that's a bit ambitious. I personally think it's going to be sometime in spring of 2021.

 

Keywords: COVID-19