RECOVER Research Update: September 2025 

This edition of the RECOVER Research Update highlights recent research on the relationships between Long COVID and other health conditions. These studies seek to answer important questions including:

• Does having another health condition put a person at greater risk of developing Long COVID?
• Does developing Long COVID put a person at greater risk of developing other new health conditions?
• Can Long COVID make the symptoms or potential outcomes of a pre-existing health condition worse? If so, which conditions, and how?
• How does improving our understanding of the relationships among other viral infections, other chronic (long-lasting) health conditions, and the long-term effects of COVID help us better diagnose, prevent, and treat Long COVID?

The association of Long COVID and CKD: Findings from the National Clinical Cohort Collaborative (N3C) (Clinical Journal of the American Society of Nephrology, August 2025)

• Researchers found that adults who have a history of serious kidney problems—specifically, adults diagnosed with either chronic kidney disease (CKD) or end-stage kidney disease (ESKD)—may be at higher risk of developing Long COVID. They also found that having Long COVID can increase an adult’s risk of experiencing serious kidney problems, including CKD and ESKD.
• In this study, researchers examined more than 2.3 million electronic health records (EHRs) collected from 59 study sites participating in the National Clinical Cohort Collaborative (N3C) COVID Enclave. They examined the data in these records in 2 ways. First, they looked at whether people whose kidneys were not working well before they got COVID-19 also developed Long COVID. Secondly, they looked at whether people who had no history of kidney problems started experiencing them after developing Long COVID.
• Researchers used a concept called a hazard ratio to estimate a person’s risk of experiencing both kidney problems and Long COVID. A hazard ratio allows researchers to compare the difference in risk experienced by 2 different groups. A hazard ratio of 1 means that both groups experience the same level of risk. A hazard ratio greater than 1 means that one group has a higher risk than the other.
• The EHR data showed that, among people who got COVID-19, the hazard ratio for developing Long COVID was 1.13 for people diagnosed with any stage of CKD compared to people without a history of kidney problems. The EHR data also showed that, among people who got COVID-19 and did not have a history of kidney problems, the hazard ratio for developing CKD was 1.65 for people with Long COVID compared to people without Long COVID.
• These findings suggest that monitoring a person’s kidney health could play an important role in helping predict, prevent, and treat Long COVID. These findings also highlight that even people with good kidney health can experience kidney problems if they develop Long COVID.

Risk of neuropsychiatric and related conditions associated with SARS-CoV-2 infection: A difference-in-differences analysis (Nature Communications, July 2025)

• COVID can affect a person’s mental and emotional health. Previous research has suggested that young people may be at especially high risk of developing conditions like changes in mood, depression, anxiety, as well as behavioral issues like obsessive-compulsive disorder (OCD), following a SARS-CoV-2 infection.
• In this study, researchers examined the EHRs of more than 1.2 million young people who received healthcare at 25 sites across the US. Researchers divided these young people into 2 groups: children between the ages of 5 and 11, and youths between the ages of 12 and 20.
• Researchers looked at whether children in these groups had or did not have COVID-19. They also compared how often members of each group experienced a broad range of mental and emotional health issues both before and after (and sometimes months after) receiving the results of their COVID-19 test.
• Researchers found that the children in the study who had COVID-19 were 1.77 times more likely to develop anxiety, OCD, attention-deficit/hyperactivity disorder (ADHD), and autism than children who did not have COVID-19. Youths in the study who had COVID-19 were about 1.5 times more likely to develop anxiety, depression, and other mood disorders than youths who did not have COVID-19.
• These findings highlight the importance of understanding the differences in how Long COVID can affect children—including children of different age groups—and adults.

HIV infection and Long COVID: A RECOVER program, electronic health record–based cohort study (Clinical Infectious Diseases, May 2025)

• People with human immunodeficiency virus (HIV) who get COVID-19 may be at increased risk of developing Long COVID because their immune systems have already been weakened by a chronic (long-lasting) viral infection.
• In this study, researchers measured that risk by examining the EHRs of more than 35,600 people with HIV compared to the EHRs of more than 4.6 million people without HIV.
• Researchers used 2 methods to determine if someone with HIV also had Long COVID: a computer program that reviewed a person’s EHR for information such as symptoms and treatments strongly associated with Long COVID (called a computed phenotype definition), and the presence of a code (called an ICD-10 code) in an EHR indicating that a healthcare provider had diagnosed a person with Long COVID.
• Researchers found a small but significant increase in the risk of developing Long COVID for people with HIV when using the computed phenotype definition. Researchers found no meaningful increase or decrease in risk when using the ICD-10 code for Long COVID.
• These findings suggest that Long COVID may be underdiagnosed in people with HIV. They also highlight that healthcare providers and researchers may face challenges in determining whether people who are already living with chronic health conditions may also be experiencing symptoms of Long COVID.

Impact of COVID-19 vaccination on symptoms and immune phenotypes in vaccine-naïve individuals with Long COVID (Communications Medicine, May 2025)

• SARS-CoV-2, the virus that causes COVID-19, can remain in the body for months after an infection. Research suggests that viral persistence may be a cause of some types of Long COVID in some people.
• Research also shows that COVID-19 vaccines can help the immune system defend the body against the SARS-CoV-2 virus. Researchers wanted to know whether targeting persistent SARS-CoV-2 virus with the COVID-19 vaccine could be an effective treatment for Long COVID.
• In this study, 16 previously unvaccinated people with Long COVID received a dose of a COVID-19 vaccine. At 6 and 12 weeks after vaccination, researchers surveyed these study participants about their overall health. Researchers also collected blood samples so they could measure the effect vaccination had on participants’ immune systems.
• Of these 16 people, 10 reported better overall health, 3 reported no change, and 3 reported worse overall health 12 weeks after vaccination.
• By analyzing the study participants’ blood samples, researchers found that specific changes in their bodies were associated with their reported health outcomes. All 16 study participants showed signs of producing more T cells (immune system cells that can destroy other cells infected by a virus) and antibodies, which can block a virus’s effects.
• However, study participants who reported no health improvement or worsening health after vaccination also had high levels of other immune-system cells called cytokines in their blood. Cytokines can trigger or increase inflammation (swelling), which is another possible cause of some Long COVID symptoms in some people.
• Although this was a small study, its findings provide direction for future research to investigate the role vaccines could play in making the symptoms of Long COVID less burdensome.

Respiratory and other infections following COVID (Pediatrics, August 2025)

• In the fall of 2022, the US saw a rapid and dramatic increase in children becoming sick due to respiratory syncytial virus (RSV). RSV can cause symptoms very similar to the common cold, flu, or COVID-19, such as congestion, fever, and difficulty breathing. In some cases, RSV can also cause death, especially in infants or older adults.
• Because this increase in RSV cases occurred so soon after the COVID-19 pandemic, researchers wanted to know if children who get a SARS-CoV-2 infection are also more likely to get an RSV infection.
• In this study, researchers examined the EHRs of more than 216,000 children 5 years old and younger. They compared the rates of RSV infection among 3 groups: children who had COVID-19, children who had the flu, and children who had another infection affecting their lungs (a respiratory infection) but not COVID-19 or the flu.
• Researchers found that children who’d had COVID-19 between March and July 2022 did not face a higher risk of either RSV infection or any other respiratory infection.
• These findings are important because they can help researchers further understand how the appearance of a novel (new) virus like SARS-CoV-2 can impact the seasonal patterns associated with other viral infections. Moreover, this increased understanding can help the medical community plan for future pandemics.

Physical function differences by COVID-19 status: A cross-sectional analysis from the RECOVER adult cohort (Physical Therapy, April 2025)

• People who have or have had COVID-19 may experience weakness, shortness of breath, and extreme tiredness (fatigue). However, few studies have sought to measure how much the effects of COVID-19 can limit a person’s physical function. Physical function refers to a person’s ability to perform everyday physical activities like taking a shower or bath, dressing, and doing basic household chores.
• In this study, researchers measured the physical function of 11,000 adults when they enrolled in the RECOVER observational study. They divided these study participants into 3 groups: people who had never had COVID-19, people who had COVID-19 in the past 3 months, and people who had COVID-19 more than 3 months ago.
• People in each of these 3 groups performed a 30-second sit-to-stand test (30STS). This test involved sitting in a chair and standing up as many times as possible in 30 seconds. Researchers then examined the results of these tests.
• Researchers did not find any meaningful differences in 30STS results across the 3 groups. However, researchers did find differences when they used RECOVER’s Long COVID research index to group people based on their Long COVID symptoms.
• People experiencing very burdensome Long COVID symptoms were able to perform fewer 30STS repetitions than people experiencing other symptoms of Long COVID. These burdensome symptoms included fatigue, dizziness, irregular or pounding heartbeat, stomach problems, and feeling worse after exerting even small amounts of physical or mental effort (called post-exertional malaise, or PEM).
• These findings are important because they suggest that people who experience a greater symptom burden associated with Long COVID may also experience challenges with physical function. For these individuals, the results of a 30STS can help inform the individualized care they need to help them manage their symptoms.

Explore the full range of RECOVER studies on how Long COVID can put a person at greater risk of developing a new health condition or experiencing the worsening of a pre-existing health condition.