Discover what the latest science from the RECOVER Initiative means for our ability to understand, diagnose, prevent, and treat Long COVID.
This page contains descriptions of findings from RECOVER research studies. These descriptions use plain language and a format that is easy to understand.
If you want to learn more about the scientific discoveries described here, you can also browse and search the complete list of RECOVER Publications.
COVID-19 can damage the heart in ways that doctors are still working to understand. Some people develop heart problems during or after COVID-19 infection, including inflammation of the heart muscle. To better understand how the virus affects the heart, researchers studied heart tissue from people who died with COVID-19. They wanted to learn what happens to the blood vessels in the heart during infection.
The research team examined heart tissue samples from autopsies using advanced techniques. These methods allowed them to see which genes were active in different parts of the tissue. They focused on cells that line the inside of blood vessels in the heart. The researchers compared tissue from 8 people who had COVID-19 to tissue from 4 people who died from other causes. They found that, in people with COVID-19, the blood vessel cells showed signs of stress and inflammation. These cells had turned on genes related to fighting infection and responding to injury. The team also found evidence of the virus itself in some heart tissue samples.
These findings help explain why some people have heart problems after COVID-19. The virus appears to directly affect blood vessels in the heart, causing inflammation and damage. Understanding these changes at the cellular level may lead to new ways to prevent or treat heart problems in Long COVID.
RECOVER researchers looked at the use of a code to diagnose Long COVID in electronic health records (EHRs). They used EHR data from over 8,000 people and compared people who had the ICD-10 code for Long COVID (which is U09.9) in their EHR on or after October 1, 2021. They also looked at other codes in their EHR for health conditions, symptoms, tests, and treatments within 60 days after their Long COVID diagnosis.
Researchers found that many doctors use the Long COVID code along with other codes. People with Long COVID had a mix of symptoms and other health conditions, tests, and treatments. This suggests there may be different types of Long COVID. The researchers concluded that for now, doctors should look at a person’s mix of symptoms and other health conditions to diagnose Long COVID.
In this study, RECOVER researchers used a computer program to identify possible types of Long COVID based on electronic health records (EHRs). They used the computer program to review EHRs of people diagnosed with Long COVID and group them based on patterns in their symptoms and health conditions.
The computer program found 6 different types of Long COVID, which were related to 1) many symptoms and health conditions with unusual lab test results, 2) the lungs, 3) the brain, 4) the heart, 5) pain and feeling weak and tired (fatigue), and 6) many symptoms and conditions with pain. Each type of Long COVID also differed based on health conditions people had before COVID-19 and how severe their COVID-19 was. This research could help identify people with different types of Long COVID to better diagnose and treat them and invite them to join research studies.
RECOVER researchers wanted to learn if there are different types of Long COVID based on symptoms and health problems that often happen together. Researchers used data from electronic health records (EHRs) of about 35,000 people diagnosed with COVID-19. The EHRs were from 2 healthcare systems in PCORnet, the National Patient-Centered Clinical Research Network. They used a computer program to look for patterns in people’s new symptoms and health problems that started 30 to 180 days after having COVID-19.
The researchers found 4 main types of Long COVID based on symptoms and health problems that happen together. The 4 types of Long COVID are related to the 1) heart and kidneys, 2) breathing, sleep, and anxiety, 3) muscles and nerves, and 4) digestive tract and breathing. This research could help define types of Long COVID to give people more specific diagnoses and treatment plans.
Many people who have had COVID-19 continue to experience symptoms for months or even years afterward. This condition, known as Long COVID, shares many similarities with another chronic illness called ME/CFS (myalgic encephalomyelitis/chronic fatigue syndrome). ME/CFS causes post-exertional malaise (PEM), which is extreme exhaustion that gets worse after physical or mental activity, along with problems sleeping, thinking clearly, and managing pain. Researchers wanted to understand how many people with Long COVID might also have ME/CFS and PEM to help doctors better identify and treat these conditions.
The study included 465 adults with Long COVID who completed online questionnaires about their symptoms. Participants had been experiencing COVID symptoms for an average of about 70 weeks. They answered questions about how often and how severely they experienced 38 different symptoms common to COVID and Long COVID. They also completed validated questionnaires specifically designed to identify ME/CFS and measure PEM. Most participants were white women living in North America.
The researchers found that 58% of people with Long COVID met the criteria for ME/CFS. Many people were unsure about their own condition. Among those who said they had ME/CFS, only 71% actually met the diagnostic criteria. Meanwhile, 40% of people who said they didn't have ME/CFS actually did meet the criteria. People who met ME/CFS criteria experienced more severe PEM symptoms overall, especially extreme tiredness, feeling worse after activity, and difficulty thinking or concentrating. They also reported greater disability in their daily activities compared to those without ME/CFS.
This research shows that ME/CFS is common among people with Long COVID. The findings suggest that many people may not realize they have ME/CFS, highlighting the need for better screening tools in medical settings. Understanding this connection could help doctors provide more targeted care and support for people experiencing persistent symptoms after COVID-19.
Loss of smell is one of the most common symptoms of COVID-19, and, for some people, it can last months or even years after infection. While most people recover their sense of smell within weeks, researchers don’t fully understand why some people experience persistent smell loss as part of Long COVID. This study aimed to uncover what happens in the nose tissue of people with long-lasting smell loss after COVID-19.
Researchers examined nose tissue samples from 24 people, including 9 individuals with Long COVID who had objectively confirmed smell loss lasting at least 4 months after their initial COVID-19 infection. They compared these samples to tissue samples from 13 people who never had COVID-19 and 2 people who recovered their smell after COVID-19. The team used advanced techniques to look at individual cells and analyze which genes were turned on or off in the tissue responsible for smell.
The study found that people with persistent smell loss had immune cells called T-cells in their smell tissue, indicating ongoing inflammation. Surprisingly, the nerve cells responsible for detecting smells appeared mostly intact, suggesting the problem wasn’t permanent damage to these cells. However, these smell nerve cells showed reduced activity by the genes needed for detecting smells. The researchers also found changes in genes related to inflammation and immune responses. These findings suggest that lingering inflammation in the nose, rather than damaged cells, may explain why some people can’t smell properly long after having COVID-19.
This research provides important clues about Long COVID smell loss and suggests it might be treatable. Since the nerve cells responsible for detecting smells remain largely intact, treatments that reduce inflammation could potentially help restore smell function. Understanding the biological basis of persistent smell loss brings us closer to helping the many people living with this challenging Long COVID symptom regain their sense of smell.
RECOVER researchers used data in electronic health records (EHRs) from children’s hospitals that were a part of the National Pediatric Learning Health System Network (PEDSnet). Researchers looked for symptoms, health conditions, and medicines children had about 1 to 6 months after a COVID-19 test. They compared children who did and didn’t have COVID-19 to learn how many children who had COVID-19 got Long COVID, and symptoms and health problems Long COVID causes in children.
The researchers learned that Long COVID is uncommon in children and happens in about 4% of children with COVID-19 compared to in about 5% - 21% of adults with COVID-19. They also learned the Long COVID symptoms and health conditions that happen most often in children include changes in smell or taste hair loss, trouble breathing, and inflammation (swelling) in the heart or muscles.
RECOVER researchers wanted to learn if a computer program could identify if people have Long COVID based on electronic health records (EHRs). They used EHRs from the National COVID Cohort Collaborative (N3C). Researchers created and used a computer program to compare people with Long COVID to those who didn’t have Long COVID (based on whether or not people had a visit to a Long COVID clinic in their EHR). The computer program looked for patterns in people’s symptoms, health conditions, and other data.
The researchers concluded their computer program could be used to identify people with possible Long COVID. The computer program found that people with Long COVID have patterns in their health care visits, age groups, symptoms and health conditions, and the medicines they take. This could help connect people with Long COVID to health care or invite them to join research studies.
Heart problems after having COVID-19 and after getting an mRNA COVID-19 vaccine
RECOVER researchers used data from over 15 million people’s electronic health records (EHR) to compare how many people have heart problems after having COVID-19 or getting an mRNA COVID-19 vaccine. They used EHR data from 40 health systems in PCORnet, the National Patient Centered Clinical Research Network.
Researchers found that the chance of having heart problems is higher after having COVID-19 than after getting an mRNA COVID-19 vaccine for men and women in all age groups. The overall chance of having heart problems after having COVID-19 or getting an mRNA COVID-19 vaccine was very low across all ages and genders. These results support the continued use of mRNA COVID-19 vaccines for all people ages 5 and older, who meet the vaccine criteria.
