The COVID-19 virus can persist in the blood and tissue of patients for more than a year after the acute phase of the illness has ended, according to new research from UC San Francisco that offers potential clues to why some people develop long COVID.
The scientists found pieces of SARS-CoV-2, referred to as COVID antigens, lingering in the blood up to 14 months after infection and for more than two years in tissue samples from people who had COVID.
"These two studies provide some of the strongest evidence so far that COVID antigens can persist in some people, even though we think they have normal immune responses," said Michael Peluso, MD, an infectious disease researcher in the UCSF School of Medicine, who led both studies.
The findings were presented at the Conference on Retroviruses and Opportunistic Infections (CROI), which was held March 3 to 6, 2024, in Denver.
Evidence of long-term infection
Early in the pandemic, COVID-19 was thought to be a transient illness. But a growing number of patients, even those who had previously been healthy, continued having symptoms, such as, brain fog, digestive problems, and vascular issues, for months or even years.
The researchers looked at blood samples from 171 people who had been infected with COVID. Using an ultra-sensitive test for the COVID "spike" protein, which helps the virus break into human cells, the scientists found the virus was still present up to 14 months later in some people.
Among those who were hospitalized for COVID, the likelihood of detecting the COVID antigens was about twice as high as it was for those who were not. It was also higher for those who reported being sicker, but were not hospitalized.
"As a clinician, these associations convince me that we are on to something, because it makes sense that someone who had been sicker with COVID would have more antigen that can stick around," Peluso said.
Virus persists for up to two years in tissue
Since the virus is believed to persist in the tissue reservoirs, the scientists turned to UCSF's Long COVID Tissue Bank, which contains samples donated by patients with and without long COVID.
They detected portions of viral RNA for up to two years after infection, although there was no evidence that the person had become reinfected. They found it in the connective tissue where immune cells are located, suggesting that the viral fragments were causing the immune system to attack. In some of the samples, the researchers found that the virus could be active.
Peluso said more research is needed to determine whether the persistence of these fragments drives long COVID and such associated risks as heart attack and stroke.
But, based on these findings, Peluso's team at UCSF is involved in multiple clinical trials that are testing whether monoclonal antibodies or antiviral drugs can remove the virus and improve the health of people with long COVID.
"There is a lot more work to be done, but I feel like we are making progress in really understanding the long-term consequences of this infection," Peluso said.
Meeting: Conference on Retroviruses and Opportunistic Infections (CROI)
The studies were supported by funding from the PolyBio Research Foundation to support UCSF's Long-Term Impact of Infection with Novel Coronavirus (LIINC) Clinical Core and a Merck Investigator Studies Program Grant. The National Institute of Health's National Institute of Allergy and Infectious Diseases also provided funding (3R01AI1411003-03S1, R01AI158013 and K23AI134327, K23AI157875 and K24AI145806). Additional support came from the Zuckerberg San Francisco General Hospital Department of Medicine and Division of HIV, Infectious Diseases and Global Medicine.
News
UCLA Scientists Uncover a “Hidden Weakness” in Some of the World’s Deadliest Cancers
A new study has uncovered an unexpected vulnerability in some of the deadliest cancers. Researchers at UCLA have identified a previously hidden weakness in some of the most aggressive cancers, pointing to a possible new way [...]
AI-designed universal coronavirus vaccine clears first human trial
Key Takeaways Super-Antigen Technology: Uses AI and machine learning to analyze viral genomes, creating a single vaccine that targets essential features across entire virus families, including coronaviruses and Ebola. Human Trials & Safety: Phase [...]
Researchers Discover a Hidden Vitamin D Problem That Persists Year-Round
A new study suggests that some groups may not experience the expected seasonal boost in vitamin D levels, even during the sunniest months of the year. Many people assume that spending more time outdoors [...]
Researchers Solve the Mystery Behind a Billion-Dollar Dental Implant Disease
Researchers have uncovered why a common and costly dental implant infection often resists antibiotics. Dental implants have helped tens of millions of people regain a full set of stable, functional teeth, something traditional dentures [...]
Nanoparticles inspired by lung fluid improve therapies targeting respiratory system
The CIC biomaGUNE Center for Cooperative Research in Biomaterials has developed pulmonary surfactant nanoparticles (the blend of lipids and proteins that line the alveoli and enables breathing), which are encapsulated [...]
Scientists Finally Uncover How a “Forever Chemical” Causes Birth Defects
PFDA, a PFAS “forever chemical,” can cause craniofacial birth defects by disrupting retinoic acid regulation during fetal development, revealing the first clear molecular mechanism behind the link. Researchers have long linked perfluoroalkyl and polyfluoroalkyl substances (PFAS), [...]
Scientists Have Discovered These Deadly Parasites Are Secretly Swapping DNA
Leishmania parasites appear to evolve through widespread genetic exchange, reshaping assumptions about how they adapt and spread. A parasite long thought to spread mostly by cloning itself may be far more genetically dynamic than [...]
Stanford’s Revolutionary New Microscope Reveals Living Cells in Stunning Detail
Stanford researchers have developed a microscope that can show how nanostructures interact inside living cells at the highest resolution achieved so far. The view into living cells just got better. Stanford researchers have merged [...]
What Bundibugyo Ebola vaccines and treatments are under development
By Mariam Sunny and Jennifer Rigby May 29 (Reuters) – Global health authorities are racing to identify medical options to help contain an Ebola outbreak in eastern Democratic Republic of Congo, linked to the [...]
Why More People in Their 30s Are Suddenly Getting Colon Cancer
A major Swiss study found that colorectal cancer is becoming increasingly common in adults under 50, even as rates decline in older age groups. Researchers in Switzerland have identified a concerning trend: while colorectal [...]
Researchers Compare MS Models to Human Tissue in Search for Better Therapies
Researchers identified key differences between two widely used multiple sclerosis models, showing how each can better study myelin damage, immune responses, and repair. The findings may improve efforts to develop treatments that restore lost [...]
Scientists Discover Genetic “Off Switch” That Supercharges CAR T Cells Against Cancer
A new study reveals a possible way to make CAR T-cell therapy more durable and effective by targeting a single gene-regulating protein. CAR T-cell therapy is widely seen as a breakthrough in personalized cancer [...]
New Vitamin B12-Based Therapy Could Change How Brain Cancer Is Treated
Researchers have identified a vitamin B12–based compound that appears capable of crossing the blood–brain barrier and selectively accumulating in glioblastoma tissue. For decades, one of the biggest problems in brain cancer treatment has had [...]
Simple Fiber Supplement Cuts Knee Arthritis Pain in Just 6 Weeks, Study Finds
A daily inulin supplement may help reduce knee osteoarthritis pain while revealing a possible link between gut health, muscle function, and pain sensitivity. For millions of people living with knee osteoarthritis, managing chronic pain [...]
This Common Vitamin May Help Stop Prediabetes From Turning Into Diabetes
Vitamin D may help prevent type 2 diabetes in people with specific genetic variations, offering a possible path toward personalized diabetes prevention. More than 40% of U.S. adults have prediabetes, a condition in which [...]
Ebola, hantavirus: Is the world prepared for the next pandemic?
Funding cuts to health research and a growing antivaccine movement are making it harder than ever to respond to viruses. The World Health Organization (WHO) has declared that an Ebola outbreak in Uganda and [...]
