A major scientific review published in Nature Reviews Disease Primers this week says long COVID neurological symptoms may persist for months or years in tens of millions—potentially up to 400 million—underscoring a growing global health burden.
Long COVID—also called post-COVID-19 condition or post-COVID conditions—generally refers to symptoms that continue or appear well after an acute SARS-CoV-2 infection. The World Health Organization (WHO) notes that post-COVID-19 condition can affect multiple body systems and estimates about 6 in 100 people who have COVID-19 develop the condition, though estimates vary by population, methods, and pandemic phase.
The Nature Reviews Disease Primers review (led by Wilson and colleagues, per the paper) focuses on brain- and nerve-related complications often reported by patients long after infection—commonly described as “brain fog,” but clinically spanning cognition, mood, sleep, sensory changes, and autonomic symptoms.
What the review says people are experiencing
The review describes neurological and neuropsychiatric symptoms that can persist at least three months after infection, including:
- Memory problems and slowed thinking
- Executive dysfunction (trouble planning, focusing, multitasking)
- Anxiety and depression
- Headaches and sleep disruption
- Loss or distortion of smell and taste
- Neuropathies (tingling, pain, numbness)
- Dizziness and symptoms linked to autonomic dysfunction, including heart-rate instability and post-exertional symptom worsening.
Clinicians and public health agencies emphasize that long COVID can occur after mild, moderate, or severe illness, and can affect children as well as adults.
How common are neurological long COVID problems?
There is no single global number that fits every study design, variant era, or health system. But across large datasets and reviews, neurological and cognitive complaints remain among the most frequently reported long COVID issues.
Table: Commonly cited ranges used in research and public health reporting
| Measure (varies by study design) | Commonly reported range | Notes |
| Share of infected people who develop long COVID (overall) | ~5%–20% in community samples | Depends on definition, follow-up time, vaccination/variant era, and reporting method. |
| Higher-risk groups | Up to ~50% reported in some hospitalized cohorts | Severe acute illness is a risk factor in many studies, though long COVID also follows mild cases. |
| WHO global estimate (overall post-COVID condition) | ~6 in 100 | WHO notes risk appears lower now than earlier, but ongoing transmission means continuing incidence. |
| Global cumulative burden estimate used in high-profile analyses | ~400 million (cumulative) | Often cited in policy and research commentary about total people affected at some point. |
Health agencies continue to track prevalence through surveys and surveillance systems, including the CDC’s long COVID monitoring and the U.S. Census Bureau’s ongoing household survey infrastructure used for related estimates.
Why these symptoms may linger: leading biological explanations
The Nature Reviews Disease Primers review highlights multiple mechanisms that may overlap in different patients—helping explain why symptoms and recovery timelines can look so different from one person to another.
Researchers commonly investigate several non-mutually-exclusive pathways:
Viral persistence and tissue reservoirs
Some studies have found evidence consistent with viral material or viral antigens persisting beyond acute infection in certain tissues, which may continue to stimulate immune responses in susceptible individuals.
Immune dysregulation and chronic inflammation
A December paper in Nature Immunology reported that people with long COVID showed persistent immune activation and proinflammatory signatures for more than 180 days after infection, including elevated IL-6 and JAK-STAT pathway activity, alongside signs consistent with immune exhaustion in some cell populations.
This type of sustained inflammatory signaling is of particular interest in neurological symptoms because it can affect the brain indirectly through immune mediators, vascular function, and the blood–brain barrier.
Endothelial injury, clotting, and microvascular effects
A growing body of research has examined vascular and endothelial dysfunction as a potential contributor—especially relevant for headaches, dysautonomia, exertional intolerance, and cognitive symptoms when oxygen delivery or microcirculation is impaired.
Microbiome disruption and gut–brain interactions
Long COVID research also increasingly focuses on microbiota dysbiosis (disrupted gut microbial communities) and the gut–brain axis, which may influence immune tone, inflammation, and neurologic symptoms.
Herpesvirus reactivation and co-infections
Some investigations have reported signals consistent with reactivation of latent viruses (including herpesviruses) in subsets of patients, potentially compounding fatigue, cognitive complaints, and systemic inflammation.
Autoimmunity
Autoimmune activity—where immune defenses mistakenly target the body’s own tissues—remains another major hypothesis being studied, especially for neurologic and autonomic symptoms.
Diagnosis and care: what clinicians are doing now
Because long COVID is heterogeneous, major guidance emphasizes symptom-based evaluation and personalized management.
The CDC describes long COVID as an infection-associated chronic condition present for at least three months that can be continuous, relapsing/remitting, or progressive, affecting one or more organ systems.
Many specialty clinics use structured assessments focused on:
- Cognitive testing or neuropsychological screening when brain fog is prominent
- Sleep evaluation when insomnia or hypersomnia is severe
- Autonomic testing when dizziness, tachycardia, or exercise intolerance is central
- Mental health screening and support for anxiety/depression
- Rehabilitation approaches that avoid worsening post-exertional symptoms in patients who experience marked crashes after activity.
New treatment trials: what’s being tested
With no single approved cure, the field is shifting toward mechanism-informed trials, including anti-inflammatory, immunomodulatory, and symptom-targeted approaches.
BioVie’s ADDRESS-LC trial (bezisterim)
BioVie reported enrollment for a Phase 2 randomized, placebo-controlled ADDRESS-LC trial evaluating bezisterim (NE3107), an investigational anti-inflammatory/insulin-sensitizer candidate intended to address cognitive impairment and fatigue in long COVID. The company has said the study is funded by a U.S. Department of Defense grant and is designed to enroll about 200 adults, with initial results anticipated in the first half of 2026.
NIH RECOVER and RECOVER-TLC platform trials
The NIH’s RECOVER effort has been building a pipeline of trials to test interventions across major symptom clusters and biological hypotheses. The RECOVER-TLC clinical trials effort has publicly discussed trial plans and protocol development steps, including work related to low-dose naltrexone and expansion of an existing study of baricitinib.
Why this matters now
Even as many countries treat COVID-19 as an ongoing respiratory virus rather than an acute emergency, long COVID remains a long-tail challenge for health systems, employers, and families.
WHO notes that the risk of post-COVID condition appears lower now than earlier in the pandemic, but emphasizes that continued transmission means new cases will keep accruing.
For neurological long COVID, the stakes include not only individual quality of life but also workforce participation, schooling, and long-term disability planning—especially when cognitive impairment and post-exertional symptom worsening limit daily function.
Table: What researchers are prioritizing next
| Priority area | Why it’s urgent |
| Better biomarkers | To distinguish subtypes and match people to therapies faster. |
| Longitudinal immune profiling | To map who stays inflamed, who recovers, and what predicts each path. |
| High-quality treatment trials | To move beyond symptom management toward disease-modifying strategies. |
| Standardized case definitions and reporting | To make studies comparable across countries and time. |
Final Thoughts
The Nature Reviews Disease Primers review adds weight to a central message researchers and public health agencies have been repeating: long COVID is not one condition with one pathway, and neurological symptoms may arise from multiple interacting mechanisms.
For patients, that complexity can be frustrating. For science, it points toward a more tailored future—where immune profiles, vascular markers, or viral persistence signals help guide therapy selection and trial enrollment. For now, prevention still matters. The CDC continues to emphasize that vaccination remains an important tool to reduce the risk of long COVID.
