Why Long COVID Is Still Destroying Lives and Medicine Has No Answers

65 million people globally have long COVID. Four years after COVID-19 first appeared, medicine still has no approved treatments. Here is why this condition is so hard to study and what research is finding.

Long COVID — the persistence of debilitating symptoms including fatigue, cognitive dysfunction ('brain fog'), breathlessness, and pain beyond the acute infection phase, in patients who have otherwise recovered from COVID-19 — affects an estimated 65 million people globally according to 2023 WHO estimates. For the most severely affected, the condition is as disabling as multiple sclerosis or heart failure, preventing work, disrupting relationships, and eliminating the activities that defined the person's pre-illness identity.

Four years after COVID-19 first circulated, medicine does not have a single FDA-approved treatment specifically for long COVID. This is not for lack of research effort — the NIH's RECOVER initiative, the UK's PHOSP-COVID programme, and dozens of independent research groups have investigated long COVID's mechanisms and potential treatments extensively. The absence of approved treatments reflects the genuine complexity of a condition that appears to have multiple underlying mechanisms in different patient subgroups.

The current mechanistic understanding identifies at least three pathological processes that contribute to long COVID in various proportions across affected individuals: viral persistence (fragments of SARS-CoV-2 RNA and protein found in tissues months after acute infection, suggesting the virus isn't fully cleared); immune dysregulation (altered T-cell function, elevated inflammatory cytokines, reactivation of latent viruses like Epstein-Barr virus that the immune system normally keeps dormant); and microbiome disruption (lasting changes in gut and potentially lung microbiome composition that alter immune function and metabolic processes).

The specific treatments showing promise in early phase trials: low-dose naltrexone (an opioid antagonist whose immunomodulatory effects at low doses may reduce the neuroinflammation contributing to brain fog); antivirals targeting persistent viral reservoirs; and specific probiotic protocols targeting the gut microbiome dysbiosis patterns seen in long COVID patients.

For the political and healthcare system dimension: long COVID predominantly affects women (approximately 75 percent of the severely affected), people of working age, and people without pre-existing conditions whose disability was unexpected. The systemic under-recognition of medically unexplained fatigue conditions — long COVID's similarities to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) whose existence was dismissed by much of the medical establishment for decades — is creating specific research and treatment access barriers.