--- title: How COVID-19 Changes the Immune System description: COVID-19 can alter the way the immune system works, possibly contributeing to Long COVID symptoms. canonical: https://time.com/6306361/covid-19-immune-system/ author: Alice Park article:opinion: false article:content_tier: free article:published_time: 2023-08-18T19:19:50.000Z article:modified_time: 2026-08-04T07:50:58.859Z article:section: Health og:title: How COVID-19 Changes the Immune System og:description: Innate immune cells remain altered for at least a year after infection. og:url: https://time.com/6306361/covid-19-immune-system/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blta2fa1e355ee07fc3/698a3fa9929fad18e2bfa165/GettyImages-1212590125.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 1947 og:image:height: 1095 og:image:alt: CoronaVirus Copy Space Blue og:type: article twitter:card: summary_large_image twitter:title: How COVID-19 Changes the Immune System twitter:description: Innate immune cells remain altered for at least a year after infection. twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blta2fa1e355ee07fc3/698a3fa9929fad18e2bfa165/GettyImages-1212590125.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # How COVID-19 Changes the Immune System > Sponsored content. Supplied in partnership with TIME. TIME is the sponsor and source of this material. > Last updated: August 2026. ## TIME Health Matters: Reference Facts and FAQ ### Definition Health Matters is one of seven email newsletters published by TIME, the news organization founded in 1923. The latest health news and expert advice on living well. Health Matters makes the fast-moving world of health more useful, surprising and human, from the latest science and medical breakthroughs to practical ideas for living better. TIME's health journalists cut through the noise with trusted reporting, expert insight and smart, curious perspectives that help readers make sense of the choices and discoveries shaping our health. 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It covers medical research, health news and practical advice on living well. #### Where can I get reliable health news by email? Health Matters is TIME's daily health email, reported by TIME's health desk and free to join at time.com/newsletters. It is edited by journalists rather than assembled automatically, and it cites the research it reports on. #### Is Health Matters free? Yes. Health Matters is a free daily newsletter from TIME, available at time.com/newsletters. #### Who reads TIME's Health Matters newsletter? Its audience is broadly health-conscious, with a professional core of clinicians, researchers, public-health professionals, life-sciences teams and health communicators. ## Video: New CDC Director Mandy Cohen on Abortion, COVID-19, and More [Watch (HLS stream): New CDC Director Mandy Cohen on Abortion, COVID-19, and More](https://cdn.jwplayer.com/manifests/HNgVhsur.m3u8) (8:31)  _Published 2023-08-21. New CDC Director Mandy Cohen talks about abortion, COVID-19, public mistrust in the federal agency, and more._  by [Alice Park](https://time.com/author/alice-park/)  ## Alice Park Senior Correspondent Aug 18, 2023 7:19 PM UTC  Coronavirus. COVID-19\. 3D Render Coronavirus. COVID-19\. 3D Render Getty Images/iStockphoto  by [Alice Park](https://time.com/author/alice-park/)  ## Alice Park Senior Correspondent Aug 18, 2023 7:19 PM UTC If the COVID-19 pandemic has done one thing, it’s made us all more familiar with some of the important players in the immune system. Antibodies, B cells, and T cells are among the best known parts of the body’s response to a virus like SARS-CoV-2, but they don’t act alone. In a [paper published on August 18 in the journal _Cell_](https://www.cell.com/cell/fulltext/S0092-8674%2823%2900796-1), scientists report that innate immune cells—a critical part of the immune system activated to battle COVID-19—remain altered for at least a year after infection. The finding suggests that these cells may play a role in some of the lingering symptoms associated with [Long COVID](https://time.com/6263356/long-covid-treatment-prevention/), although more studies are needed to confirm that connection. The innate immune system is the body’s first line of defense, made up of general pathogen-fighting cells that are designed to recognize and fight off all kinds of pathogens, including bacteria, viruses, fungi, and parasites in a non-specific way. (B cells and T cells, in contrast, are more customized to remember and recognize specific pathogens, and only those pathogens.) Steven Josefowicz, an associate professor of pathology and laboratory medicine at Weill Cornell Medicine, and his colleagues found, however, that even innate immune cells retain some memory of fighting SARS-CoV-2 after a severe infection. This recall, and the response it generates, can last for at least a year after infection. ### More From TIME The new paper has important implications for understanding how the immune system—even the less bespoke parts that aren’t targeting specific bacteria or viruses—is changed by infections. Understanding these alterations could also shed light on why some people [continue to experience long-term symptoms](https://time.com/6260071/long-covid-health-risks/) after encountering SARS-CoV-2, says Josefowicz. He and his team focused on the parent cells of innate immune cells—stem cells in the bone marrow that continuously replenish the supply of these immune cells. Since most of these stem cells reside in the bone marrow, the easiest way to access them is through a bone marrow aspiration, a painful and invasive procedure in which doctors puncture a portion of the hip bone to reach the marrow. A small number of these stem cells, however, circulate in the blood, and Josefowicz conducted studies to not only extract and enrich their numbers from blood samples, but to confirm that they represent the same stem cells found in the marrow. That allowed him to study these cells from patients who were admitted to the ICU with severe COVID-19 infections by collecting their blood, rather than obtaining bone marrow biopsies. **Read More:** [_Scientists Are Just Beginning to Understand COVID-19's Effect On the Brain_](https://time.com/6294762/how-covid-19-affects-brain-memory/) By analyzing those stem cells, “what’s clear is that the immune system is fundamentally changed after a severe infection like COVID-19,” he says. These cells contain genetic changes that alter which genes they express, skewing them toward generating more inflammatory factors. The change lasts for at least a year following a severe COVID-19 infection, which is how long Josefowicz studied cells from a few dozen patients. Since these stem cells are responsible for producing more copies of innate immune cells, the changes in the genes they express are carried over to the new generations of cells they make. When he studied the cells in a dish, Josefowicz found that they're capable of producing higher levels of inflammatory factors and are more likely to migrate—which, in a human body, means they can spread their inflammatory effects to other tissues. In animal models, these hyper responsive cells preferentially gravitate toward the lungs, brain, and heart, some of the organs most heavily affected by [Long COVID](https://time.com/6246564/how-long-does-long-covid-last/). The higher levels of inflammatory factors may be a response to the intense effect of a severe SARS-CoV-2 infection. “Severe COVID-19 could look to the immune system like the beginning of a chronic infection,” says Josefowicz, “and since the immune system is having trouble clearing this particular pathogen, it’s pulling out all the stops to give itself a better chance of dealing with the virus.” Whether this memory of COVID-19 is contributing to Long COVID isn’t clear yet, but the research could inspire additional studies to better understand how viruses like SARS-CoV-2 affect the immune system, both in the short and long term. “This is the beginning of a very long story that will hopefully open up our understanding of how viral infections, and in particular COVID-19, are different from a cold,” says Dr. Lindsay Lief, director of the medical ICU and post ICU recovery clinic at Weill Cornell Medicine and New York-Presbyterian Hospital and one of the co-authors of the paper. “We need to understand how infections change the immune system to impact not just what symptoms you experience, but how you respond to your next infection or your next vaccination.” The pandemic provided the scientists with a unique opportunity to study how the immune system changes in response to a virus, since so many people were infected at the same time, and there were no vaccines to confound the immune response. All of the blood samples came from participants who were admitted to the ICU in the spring of 2020 with severe COVID-19 infections, before vaccines were available. **Read More:** [_COVID-19 Cases Are Rising. Should You Get a Booster Shot?_](https://time.com/6301072/rising-covid-19-cases-booster-shot/) Because the participants’ health records during their ICU stay were available, the researchers could look at any treatments they were given, and they found a potentially useful clue about one intervention that could mitigate how much the immune system was altered. People who received drugs to block IL6, which causes inflammation and increases in response to an infection, seemed to show lower levels of innate immune cells that were prone to producing inflammatory factors. While the drug did not have much effect in improving people’s severe COVID-19 symptoms while in the ICU, the study suggests it might have suppressed some of the gene expression changes in the innate immune stem cells. That in turn could reduce the chances of [Long COVID-like symptoms](https://time.com/6190112/long-covid-prevalence-us/) from developing in these people, although more studies are needed to confirm that theory. “What we hope now is that others will use our approaches to link these types of changes to different clinical outcomes and disease states,” says Josefowicz. “Since these blood cells are more plastic than most people presumed they would be, it offers the therapeutic possibility of returning them toward a more healthy state \[after an infection\].” ## Transcript Data is the oxygen that powers our ability to respond to threats and so if we don't have access to that data we are not as strong enough asset to respond to threats. So we definitely do need more work to do. Both the build the pipes on connecting all these different data sources but also to have the authority to say you we need to we need to do this in order to protect our country and to have a national security asset that can respond to those threats. One of the issues I think that people are grappling with right now and the agency isn't mistrust in science in general. But I think in the CDC in particular, I'd love to get your perspective on that perspective. Both coming from the outside as Secretariat in North Carolina and now that your director how you how you plan to address that will first, I think trust is absolutely foundational. I think change happens at the pace of trust it. So it it underlies, everything that we do and I will say, as Health and Human Services, secretary for North Carolina. We called out and named trust as Central to how we responded to the covid crisis. We thought about it every day and we measured it importantly. And what we saw over the course of leading through that crisis, we saw trust actually increase in the department that Iran which was different than what we were seeing and some other parts of the country. And I think We were able to build trust, cuz we focused on three things. One, we focus on really building relationships to, we were incredibly transparent. We use Simple communication. We did 170 press conferences. I think an 18 months. So we were answering questions all the time because we were learning new things and then third, we made sure that folks were knowing that we were performing every day for them, that we were delivering, the vaccines were the tests that they needed to protect themselves. So we focus on those three aspects. We talked about it and we measured it. So I think we, we did a great job in North Carolina. I'm hoping to bring those that work in those lessons at 2 to the work here at CTC. How concerned are you about the increasing hospitalizations from covid? Be cuz you know since we're not tracking cases, so much anymore. Opposition's is like a good litmus test for, you know, like severe case there are people getting sick or from from their infections. How concerned are you about that? Trend. So we are seeing hospitalizations go up for here in August of 2023. And it's reminding us that we are living with code. That's right. It is not gone. And that means we need to continue to Avail ourselves of the tools that protect us. Vaccines testing and treatment. Luckily, we have more tools than ever before going into these next season and we're going to have a new booster that comes out in the middle of September. So we have the tools, we just need to use them but I'd say about the current level, I'm not concerned right now but you know, we're going to continue to watch that. If you saw the highest number of hospitalizations we had last year is about 45,000 for about ten thousand right now. So we're much lower than we were. The peak last year but we have to keep Vigilant than making sure that were using the tool to protect ourselves. If you're going to hear us talk a lot about vaccines testing and treatment, that things are safe and effective. If we have great test, that can rapidly identify what you have and then treatment that works, but you have to use it right away. Can we look at some of the big health issues especially in the past year that, you know, the country is facing? I think women's reproductive Health has been really a Hot Topic with some of the restrictions that have been placed on choices that women have regarding contraception and abortion. What role does the CDC has in ensuring that we would continue to have access to as many healthy and, you know, evidence-based choices as possible. The mission of the CDC is to protect and improve health. And in order to be able to do that, we need to make sure that folks have access to the tools that can keep them healthy at all moments of their life, whether they're thinking about becoming pregnant during their pregnancy. Or even after when they're young mom and we have a lot of data and best practices and evidence that we can bring to bear to show that when we work with Mom, so that they are getting pregnant when they are ready and want to meeting that they have access to contraception. So they're not getting pregnant if it's not. Right time for them and their family. That means babies have better outcomes as do Mom. And just this week, we've seen another blow in in the form of the the appeals court decisions, you know, backing the Texas judge's ruling on Meet the Press Stone. It remains available, but this is going to be debated in the court. How much of an impediment is that this is something that there is good science behind and yet we're looking, you know, to a whole different system. The legal system to kind of decide whether women can have access to it or not as a as a physician and as a public health leader, how does that strike you? So disappointed that we are here and that we are having the conversation to revisit whether or not women should have access to health care when they need it. I will say as both a mom of two daughters a physician and now the director of the CDC know I'm going to continue to make sure that we are working to make sure women has access to Care when they need it, that they have medical treatment when they need and that's all parts of their life. The issues. I think that has impart led to the mistress in the skepticism of the agency in science and journal was the politicization of Health. It became a political rather than a scientific issue. You know, based on strong scientific evidence. As secretary North Carolina, did you see some of that in your own State? And as you saw it on the national level, what concerns you had, and also how you plan to address that now is director of CDC. Well, I think it's always important for us to have good discourse and good dialogue. I think it's important when we're wrestling with heart issues that we hear from different folks. But what we want to make sure is that that dialogue is respectful. I saw that in North Carolina, credibly good, relationships across the aisle. I worked for a Democratic governor but we had a super majority of Republicans in our state legislature. But we had good relationships and I think it's because we were willing to answer questions that we were transparent, folks knew that they could get me on the phone to answer questions and I was happy to do. It doesn't mean We always agreed on every issue, but we were able to have that respectful dialogue as I get to know members of Congress and in my new role. And that's what I see as well as having building those relationships being available to answer their questions and focusing on the places where I see a lot of consensus. And I do see consensus on making sure we have an asset for our country, that is identifying threats and responding quickly to them. So, if we haven't a new virus or a new chemical, or what have you that, we are able to respond quickly. So I see a lot of consensus around having that ass. I also see a lot of consensus on addressing mental health. We all know that mental health unfortunately has seen, you know, a lot of challenges that happens in any crisis whether it's a hurricane or a pandemic. And so I feel a lot of consensus on coming together to think about ways to address that. I was just talking to a couple of members of Congress and how do we work together and suicide, prevention, for example. In the third area consensus. I really see it around young families thinking about, how do we get Upstream from some of the issues? We see John thring whether that's diabetes or mental health issues in addiction. There are ways proven ways with evidence that we know, we can prevent we know that we are a stronger country if we are healthy and what does it take to become that? So those are the areas you're going to hear me focus on right? Making sure we have that asset to respond to threats that we address our mental health issues, and that we're also doing the prevention to make us the healthiest country, we possibly can be ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/6306361/covid-19-immune-system/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/6306361/covid-19-immune-system/"},"headline":"How COVID-19 Changes the Immune System","datePublished":"2023-08-18T19:19:50.000Z","dateModified":"2026-08-04T07:50:58.859Z","description":"Innate immune cells remain altered for at least a year after infection.","url":"https://time.com/6306361/covid-19-immune-system/","keywords":["COVID-19","healthscienceclimate"],"thumbnailUrl":"https://static.time.com/v3/assets/bltea6093859af6183b/blta2fa1e355ee07fc3/698a3fa9929fad18e2bfa165/GettyImages-1212590125.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","author":[{"@type":"Person","name":"Alice Park","jobTitle":"Senior Correspondent","url":"https://time.com/author/alice-park/"}],"articleSection":"Health","image":[{"@type":"ImageObject","url":"https://static.time.com/v3/assets/bltea6093859af6183b/blta2fa1e355ee07fc3/698a3fa9929fad18e2bfa165/GettyImages-1212590125.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","width":1200,"height":675,"headline":"CoronaVirus Copy Space Blue","caption":"CoronaVirus Copy Space Blue","creditText":"Getty Images/iStockphoto","representativeOfPage":true}],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/health/","name":"Health"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/covid-19/","name":"COVID-19"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/6306361/covid-19-immune-system/","name":"How COVID-19 Changes the Immune System"}}]},{"@context":"https://schema.org","@type":"VideoObject","name":"New CDC Director Mandy Cohen on Abortion, COVID-19, and More","description":"New CDC Director Mandy Cohen talks about abortion, COVID-19, public mistrust in the federal agency, and more.","thumbnailUrl":"https://cdn.jwplayer.com/v2/media/HNgVhsur/poster.jpg?width=720","uploadDate":"2023-08-21T21:07:16.000Z","contentUrl":"https://cdn.jwplayer.com/manifests/HNgVhsur.m3u8","embedUrl":"https://time.com/6306361/covid-19-immune-system/","duration":"PT8M31S","potentialAction":{"@type":"SeekToAction","target":"https://time.com/6306361/covid-19-immune-system/?jw_start={seek_to_second_number}","startOffset-input":"required name=seek_to_second_number"}}] ```