你是一个从未患过COVID的人吗？ Science Has Some Clues Why
BU expert says researchers are working to understand why some people have avoided the virus or showed no symptoms when infected
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Are You a Novid, or COVID Super-Dodger—Someone Who’s Never Had COVID? Science Has Some Clues Why
BU infectious diseases expert Sabrina Assoumou says researchers are working to understand why some people have avoided the virus or showed no symptoms when infected
All summer long, we’ll be reposting stories that originally published during the 2022–2023 academic year—stories about research, BU classes, food, alumni and student profiles, and more.
If you haven’t had COVID-19 yet, explain yourself, please.
How is that possible? Globally, there have been more than 663 million cases of COVID since the virus first began circulating. Your family has probably had it. Your colleagues. Your neighbors. Your mailman, manicurist, and hair stylist. Your dog probably even had it. Stories of those who’ve somehow avoided the virus seem impossible to fathom now that three years have passed since it first started spreading around the world in early 2020.
But for scientists, these so-called “super-dodgers,” or Novids, or COVID virgins, as some are calling them, are important research subjects. If scientists can determine whether they have some unknown antibody, or genetic code, or mysterious cell makeup that has helped them ward off COVID the way Superman deflects bullets, then perhaps that knowledge could be used to create better vaccines or treatments for everyone.
According to one recent study on this subject: “Despite some inconsistent reporting of symptoms, studies have demonstrated that at least 20 percent of individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) will remain asymptomatic.” The study says that while most global research has focused on understanding why some people get severely ill, or die, from COVID, it’s also vital to understand why a small population doesn’t get it at all, or shows no symptoms when infected.
BU Today wanted to understand this better, so we turned to Sabrina Assoumou, a BU Chobanian & Avedisian School of Medicine assistant professor of medicine and the inaugural Louis W. Sullivan Professor of Medicine. She is also an attending physician in infectious diseases at Boston Medical Center, BU’s teaching hospital, and has been studying SARS-CoV-2 since its earliest days.
This interview has been edited and condensed for clarity.
Q&A
with Sabrina Assoumou
BU Today: Let’s start with this: why haven’t some people gotten COVID? Luck? Genetics? Cautiousness? Or a combination of these?
Assoumou: It is likely a combination of many factors. Vaccination is the number-one reason I would say. That’s the major factor. Cautious behavior is big. Wearing masks on public transportation and other crowded settings matters. We know that masks work and provide another layer of protection. But socioeconomic status is another factor. If you can work from home as opposed to working on the front line, that matters. Even if you’re vaccinated and masked, but you’re working in a crowded bar area, infection might be hard to avoid. And then there is luck. If you happen to be sitting for a prolonged period of time next to someone who is infected, it might be difficult to avoid infection.
BU Today: Are scientists still interested in these people, even now, three years into the virus?
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BU Today: What are the challenges for scientists?
Assoumou: It’s hard right now because many people have been infected. Omicron is very transmissible, so many people got infected. It therefore became harder to find people who haven’t been infected, to find what genes could be impacted. It made the task a lot harder.
But earlier in the pandemic, there was a study that was done where they looked at something called HLA, which is the human leukocyte antigen, which signals the immune system. They found that some people who had a mutation in the genes coding for HLA seemed to be less likely to have symptomatic infection. [According to one scientist on the research, “Not even a sniffle, not a scratchy throat, entirely asymptomatic.”] Patients seemed more likely to have asymptomatic infections.
We haven’t yet identified something as clearly helpful as what we saw with HIV. For SARS-CoV-2, we have seen mutations that make you more likely to have less severe complications or be asymptomatic.
BU Today: I’ve also read about how some people who have certain T-cell levels might be better protected against severe COVID than others. Can you talk about that?
Assoumou: In samples from people who have not yet been exposed to SARS-CoV-2, scientists found that individuals who had been exposed to other coronaviruses [but not SARS-CoV-2] seemed to have T cells that were also primed to target SARS-CoV-2 along with other coronaviruses. So when you are exposed, your immune system responds quickly because it is ready, and you’re more likely to have milder disease.
BU Today: Is it possible that those people who believe they’ve never had COVID actually did have it? But their symptoms were so minor they never bothered testing and therefore never realized they had it?
Assoumou: Yes, that is correct. There are studies that show that some individuals who didn’t think that they had been infected were in fact found to have had COVID in the past when they were tested. We know this because there are tests that can identify people who have previously been exposed to the virus.
BU Today: That would seem most likely with families or colleagues in close proximity at work. We hear these stories of entire families getting sick with COVID, but one family member not getting it. Has that been studied or explained?
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BU Today: As scientists learn more about this virus, where can they go next with their findings?
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BU Today: But it sounds like there is still a lot to learn.
Assoumou: We are building the airplane as we fly it. For example, we started out thinking that reinfections might not be common. Now we are seeing more reinfections. If you have had it, that protection is often very temporary. We are learning.
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