No published evidence shows that COVID-19 directly causes leukemia. No large epidemiological study has established SARS-CoV-2 as a trigger for any type of blood cancer, and the virus is not classified as an oncogenic (cancer-causing) pathogen. That said, research over the past few years has revealed that COVID-19 does affect the bone marrow and blood-forming cells in ways that raise legitimate scientific questions, and at least one documented case showed COVID-19 producing blood abnormalities so close to leukemia that clinicians initially could not tell the difference.
Why This Question Keeps Coming Up
The concern is not entirely baseless. SARS-CoV-2 is unusual among respiratory viruses in the breadth of its effects on the blood system. Severe COVID-19 frequently causes abnormal blood counts, destroys certain white blood cells, and triggers intense inflammatory cascades that reach deep into the bone marrow. Some patients develop changes in their blood work that look alarming on paper, even when no cancer is present. And a small number of case reports have described patients who were diagnosed with acute leukemia around the same time they tested positive for COVID-19, which understandably fueled speculation about a possible link.
To sort through whether COVID-19 could plausibly lead to leukemia, it helps to look at the specific biological mechanisms the virus engages with and how far each one falls from actually initiating a blood cancer.
What SARS-CoV-2 Does to Bone Marrow
Your bone marrow is the factory that produces all blood cells, including the white blood cells that go haywire in leukemia. COVID-19 disrupts this factory in several documented ways. Research has identified a cluster of mechanisms behind these disruptions: the massive release of inflammatory signaling molecules (sometimes called a cytokine storm), the virus directly interacting with bone marrow cells through various receptors, and the side effects of treatments like corticosteroids used to manage severe illness.1PubMed. Bone marrow alterations in COVID-19 infection: The root of hematological problems These factors can cause low blood cell counts across one or more cell lines, destruction of bone marrow tissue, and a phenomenon called hemophagocytosis, where immune cells start consuming other blood cells.
Laboratory work has also shown that the ACE2 receptor, the doorway SARS-CoV-2 uses to enter cells, is present on very early blood cell precursors found in umbilical cord blood. These tiny precursor cells can develop into both blood-forming stem cells and blood vessel-lining cells, meaning the virus has at least theoretical access to the seeds from which all blood cells grow.2Stem Cell Reviews and Reports. SARS-CoV-2 Entry Receptor ACE2 Is Expressed on Very Small CD45− Precursors of Hematopoietic and Endothelial Cells and in Response to Virus Spike Protein Activates the Nlrp3 Inflammasome Having access to a cell, though, is very different from transforming it into a cancer cell. No study has shown SARS-CoV-2 inserting itself into human DNA or hijacking the growth controls of these stem cells the way known cancer-causing viruses do.
DNA Damage Without Cancer
One of the more striking findings in recent virology research is that SARS-CoV-2 does appear to damage cellular DNA. Infected cells show signs of genetic harm: small fragments of chromosomes budding off into separate compartments (called micronuclei), activation of DNA repair systems, and measurable breaks in DNA strands.3PubMed Central. SARS-CoV-2 and the DNA damage response This sounds alarming, and it should be taken seriously by researchers, but DNA damage by itself is not cancer. Your cells sustain thousands of DNA-damaging events every day from normal metabolism, ultraviolet light, and other routine exposures, and the vast majority are repaired without consequence.
What matters for cancer is whether DNA damage accumulates in the right genes, escapes repair, and occurs in cells that continue dividing. SARS-CoV-2 does not integrate its genetic material into your chromosomes (it is an RNA virus that replicates without a DNA phase in the nucleus), and there is no evidence it selectively damages the specific genes known to drive leukemia. The DNA damage observed so far appears to be a byproduct of the intense cellular stress caused by the infection, not a targeted attack on growth-regulating genes. Researchers are still studying the long-term implications, but characterizing this as a cancer-initiating event would be a stretch given current data.
Clonal Hematopoiesis and Severe COVID
A more nuanced piece of this puzzle involves something called clonal hematopoiesis of indeterminate potential, or CHIP. This is a condition where a small population of blood stem cells in the bone marrow acquires a genetic mutation and begins producing a disproportionate share of blood cells. CHIP is common in older adults and is associated with a slightly elevated risk of developing blood cancers over many years, though most people with CHIP never develop cancer at all.
Research found that hospitalized COVID-19 patients had a higher prevalence of CHIP compared to what you would expect in the general population, and that CHIP was linked to a more severe course of infection with a distinctly altered immune response.4PubMed Central. Increased prevalence of clonal hematopoiesis of indeterminate potential in hospitalized patients with COVID-19 The important detail here is the direction of the relationship. The findings suggest that people who already had CHIP were more likely to end up hospitalized with COVID, not that COVID caused CHIP. People with pre-existing CHIP may have a dysregulated inflammatory response that makes them more vulnerable to severe infection. Whether severe COVID-19 can accelerate the expansion of existing CHIP clones or create new ones is still an open question, but no study has yet shown that COVID-19 initiates CHIP where none existed before.
When COVID Mimics Leukemia
Perhaps the most unnerving phenomenon documented in the medical literature is COVID-19 producing blood findings that look almost identical to acute leukemia. At least one published case report describes a patient whose blood work after COVID-19 showed a surge in blast cells, the immature white blood cells that define leukemia. The initial interpretation pointed toward acute leukemia. But the blasts resolved on their own without any cancer treatment, revealing the episode to be a transient reaction to the viral infection rather than a true malignancy.5International Journal of Laboratory Hematology. Transient increase in blast count following COVID‐19 infection mimicking acute leukemia
This is a genuinely important finding for patients and clinicians alike. If you have abnormal blood counts discovered around the time of a COVID-19 infection, there is a real possibility that those counts are reactive rather than cancerous. That does not mean leukemia should be dismissed, but it does mean that careful follow-up and repeat testing after recovery from the infection are crucial before jumping to a cancer diagnosis. The immune system under extreme viral stress can produce cells that look dangerous under a microscope but are actually doing what they are supposed to do in an emergency.
Case Reports of Simultaneous Diagnosis
Several published case reports describe patients who were diagnosed with acute myeloid leukemia (AML) and COVID-19 at the same time. In one case, a 57-year-old woman was found to have both severe COVID-19 pneumonia and AML concurrently, and her leukemia treatment had to be delayed so the pneumonia could be addressed first.6PubMed Central. Concurrent Diagnosis of Acute Myeloid Leukemia and Symptomatic COVID-19 Infection: a Case Report Successfully Treated with Azacitidine-Venetoclax Combination In another, a 41-year-old man presented with fever and abnormal bleeding, and testing revealed both AML and a positive COVID-19 test. He was treated for the virus first and then started chemotherapy once his viral test came back negative.7PubMed Central. Concurrent Diagnosis of Acute Myeloid Leukemia and COVID-19: A Management Challenge
These cases understandably feed the worry that COVID-19 somehow triggered the leukemia. But the timing of a diagnosis is not the same as the timing of disease onset. Leukemia develops over weeks to months before it produces symptoms severe enough to send someone to the hospital. The most likely explanation in these cases is that leukemia was already developing silently and the immune suppression it caused made the patient more vulnerable to catching COVID-19, or the symptoms from one condition simply led to the discovery of the other. A person who goes to the hospital for a respiratory virus and gets routine blood work is far more likely to have a pre-existing blood cancer detected incidentally than someone who never gets tested.
EBV Reactivation and Why It Matters
There is an indirect route by which COVID-19 could theoretically raise the risk of certain blood cancers, though it runs through a different virus entirely. Epstein-Barr virus (EBV) infects most people at some point in their lives and then stays dormant in the body permanently. Under conditions of immune suppression, EBV can reactivate and, in rare cases, contribute to the development of certain lymphomas. COVID-19, particularly severe cases, has been shown to reactivate EBV at a meaningful rate. One study of 185 COVID-19 patients found that among those who developed long COVID symptoms, roughly two-thirds showed signs of EBV reactivation.8PubMed Central. A case of Hemophagocytic syndrome due to reactivation of Epstein-Barr virus after novel coronavirus infection
This does not mean those patients went on to develop lymphoma. EBV reactivation is common in many stressful or immunosuppressive situations and rarely leads to cancer. But in at least one documented case, a patient developed a dangerous condition called hemophagocytic lymphohistiocytosis (HLH) after COVID-19, and the underlying trigger turned out to be an EBV-positive large B-cell lymphoma that had not been detected before. The researchers framed this as a “threshold model,” where compounding insults like a COVID-19 infection layered on top of an already-simmering EBV-driven lymphoma pushed the immune system past a breaking point.9PubMed Central. Unmasking Epstein-Barr Virus (EBV)-Positive Large B-Cell Lymphoma as an Underlying Trigger in a Post-COVID Hemophagocytic Lymphohistiocytosis Case In other words, COVID may have unmasked or accelerated an existing process rather than starting one from scratch.
What Happens When People With Leukemia Get COVID
A separate but related concern is how COVID-19 affects people who already have leukemia, since the immune system in these patients is compromised by both the disease and its treatment. The picture here has improved substantially since the early pandemic. A single-center survey of 30 patients with chronic myeloid leukemia (CML) found that about 57% had mild or no symptoms from COVID-19, about 23% had moderate symptoms that did not require hospitalization, and 20% had severe illness requiring intensive care. No one in the group died from the infection, though more than half temporarily stopped their cancer treatment while sick.10PubMed Central. Clinical Outcomes of Patients with Chronic Myeloid Leukemia and COVID-19 Infection-A Single Center Survey
For chronic lymphocytic leukemia (CLL), another common type, the picture was initially grimmer but also improved over time. During the Omicron wave, the overall fatality rate among CLL patients dropped to below 2%, though patients who were hospitalized for either CLL or COVID-19 and had impaired immune function faced a roughly 23% chance of dying within 30 days.11PubMed Central. Patients with CLL have a lower risk of death from COVID-19 in the Omicron era The takeaway for leukemia patients is that COVID-19 is a serious infection to avoid, but outcomes have improved with newer variants, vaccination, and antiviral treatments.
Long COVID and Lasting Blood Changes
Even after recovery from acute infection, some people experience persistent alterations in their blood that last for months. A review of the evidence found that long COVID is associated with sustained low lymphocyte counts, changes in red blood cells, anemia, and elevated levels of inflammatory markers.12PubMed Central. Hematological alterations associated with long COVID-19 These findings are concerning on their own terms because they suggest the bone marrow and blood system can remain in a state of stress well beyond the acute illness. But persistent inflammation and abnormal blood counts are not the same as pre-leukemia. Many chronic conditions cause similar blood patterns without any progression toward cancer.
What remains genuinely unknown is whether the bone marrow stress imposed by severe COVID-19 has any long-term consequences for cancer risk over a span of decades. The pandemic is still young enough that researchers simply do not have the follow-up data to answer that question. Population-level cancer registries will eventually reveal whether COVID-19 survivors develop blood cancers at higher rates than expected, but that analysis requires years of data collection and careful adjustment for confounders. For now, the honest answer is that no signal has emerged, but the surveillance period is still short.
How COVID-19 Compares to Viruses That Actually Cause Blood Cancer
A handful of viruses are established causes of blood cancers. HTLV-1, for instance, causes adult T-cell leukemia/lymphoma through a mechanism that involves integrating its genetic material directly into the host cell’s DNA and producing proteins that interfere with growth controls and DNA repair over many years. EBV contributes to certain lymphomas through similarly intimate and sustained interaction with infected cells. These are viruses that set up permanent residence in the cells they target and gradually corrupt the machinery that keeps cell growth in check.
SARS-CoV-2 does none of these things. It does not integrate into your DNA. It does not produce known oncoproteins. It does not establish a permanent latent infection in bone marrow stem cells. The damage it causes to the blood system appears to be inflammatory and transient rather than genetic and progressive. That does not rule out every theoretical pathway, particularly indirect routes like immune exhaustion enabling other oncogenic viruses to reactivate, but it places COVID-19 in a fundamentally different category from viruses with established roles in blood cancer.
Practical Guidance for Worried Patients
If you had COVID-19 and are now worried about leukemia, the most reassuring fact is that no population-level data links the two. Routine blood work abnormalities after COVID-19 are common and usually resolve within weeks to months. If your doctor flags unusual results after a recent infection, the most likely explanation is reactive changes from the virus itself. Repeat testing after recovery clears up most ambiguous findings.
If you have an existing blood cancer and are navigating COVID-19, the evidence suggests outcomes have improved substantially since the first pandemic waves. Vaccination, antiviral medications, and the generally milder nature of recent variants have all contributed to lower fatality rates. Interrupting cancer treatment during acute COVID-19 is sometimes necessary, and the available evidence shows that short pauses do not appear to have catastrophic effects on leukemia control, though any treatment changes should obviously happen in close coordination with your oncologist.
The broader lesson is one of proportion. COVID-19 affects the blood system in real and sometimes dramatic ways. It can mimic leukemia on lab tests, disrupt bone marrow function, damage DNA at a cellular level, and reactivate dormant viruses. Each of these findings is worth tracking in the years ahead. But the leap from “the virus stresses the blood system” to “the virus causes blood cancer” is enormous, and no evidence has bridged that gap.