Long Covid Newsletter
Issue #34April 27, 20267 studies

Women face double the long COVID risk compared to men in 2,698-person study

This week's research reveals striking patterns in who gets long COVID, what's happening in their bodies, and how different variants affect recovery. The findings paint a complex picture of persistent inflammation, blood flow problems, and surprising sex differences.

🚺 Women Show Double the Long COVID Risk in Largest Sex-Difference Study

  • Women had nearly double the risk of developing long COVID compared to men (odds ratio 1.95) in a study of 2,698 Spanish COVID patients tracked for one year

  • Female patients reported more persistent symptoms and had lower recovery rates at 12 months (23% vs 34% for men)

  • Fatigue was the most common symptom in both sexes but hit women harder—36% of women vs 26% of men still had fatigue at 3 months

Why it matters: These findings suggest biological sex plays a major role in long COVID susceptibility, potentially pointing to hormonal, immune, or other sex-linked factors that could inform targeted treatments.

Top 30% journal 🔗 International journal of women's health Journal Article 🗓️ Apr 22

Key Findings

🩸 Blood Clotting Problems Persist for Over a Year

  • D-dimer levels (a clotting marker) remained elevated in 65.79% of long COVID patients 7-12 months after infection in a study of 3,783 Chinese patients

  • Prothrombin time stayed abnormal in 17.29% of patients, indicating ongoing blood clotting dysfunction

  • Most inflammatory markers recovered, but clotting problems showed little improvement even a year later

💡 Persistent blood clotting issues may explain why some long COVID patients face ongoing cardiovascular risks.
🔗 Blood vessels, thrombosis & hemostasis Journal Article 🗓️ Apr 20

🧠 Brain Tissue Shows Widespread Damage in Severe Cases

  • Analysis of 352 postmortem COVID brains revealed disrupted blood-brain barriers, brain bleeding, and oxygen-starved tissue damage

  • Neuroinflammation appeared in key brain regions including the olfactory bulb, brainstem, and cerebellum

  • Protein clumps associated with neurodegeneration were found in the midbrain and memory centers

💡 Brain tissue damage may help explain persistent cognitive symptoms and smell loss in long COVID patients.
🥉 Top 5% journal 🔗 Brain pathology (Zurich, Switzerland) Review 🗓️ Apr 22

💨 Muscle Oxygen Delivery Fails During Exercise

  • Long COVID patients (46 people) showed impaired muscle oxygenation during exercise compared to 10 controls, with problems worsening on day 2 of testing

  • Muscle oxygen levels normalized too quickly during exercise, suggesting poor oxygen delivery and recovery

  • The oxygen delivery problems got worse with repeated exercise, potentially explaining post-exertional fatigue

💡 Faulty oxygen delivery to muscles may explain why long COVID patients feel exhausted after physical activity.
Top 30% journal 🔗 Physiological reports Journal Article 🗓️ Apr 24

🔬 Blood Thickness Linked to Heart Rate Problems

  • Higher blood viscosity was associated with dysautonomia (nervous system dysfunction affecting heart rate and blood pressure) in 185 long COVID clinic patients

  • 32% of patients with the thickest blood had POTS or orthostatic hypotension vs 23% with thinner blood

  • Blood thickness didn't correlate with overall symptom burden, suggesting it specifically affects the autonomic nervous system

💡 Thicker blood may contribute to the heart rate and blood pressure problems many long COVID patients experience.
Top 50% journal 🔗 American heart journal plus : cardiology research and practice Journal Article 🗓️ Apr 20

😴 Sleep Brain Waves Show Abnormal Patterns

  • 28 long COVID patients showed disrupted sleep spindles and slow brain waves during facility-measured sleep studies compared to 28 healthy controls

  • Brain wave coupling patterns were altered, with early spindle-slow wave coupling linked to worse sleep quality

  • Sleep EEG changes were similar to but distinct from those seen in chronic fatigue syndrome patients

💡 Abnormal brain wave patterns during sleep may explain why long COVID patients wake up feeling unrefreshed.
🎖️ Top 10% journal 🔗 Sleep Journal Article 🗓️ Apr 22

🏥 Diagnostic Gaps Hit Disadvantaged Groups Hardest

  • Long COVID diagnoses were skewed toward white, female, and privately insured patients compared to the overall COVID population in Advocate Health-Midwest data

  • Among Medicaid patients, Black patients were underrepresented in long COVID diagnoses by 5.4 percentage points

  • Hispanic patients made up 12.1% of long COVID diagnoses vs 14.3% of COVID cases, suggesting potential underdiagnosis

💡 Healthcare access barriers may prevent many disadvantaged patients from getting long COVID diagnoses and care.
Top 20% journal 🔗 Preventive medicine reports Journal Article 🗓️ Apr 20

Implications

This week's research reveals long COVID as a complex, multi-system condition with clear biological markers—from persistent blood clotting problems to disrupted brain waves during sleep. The striking sex differences and diagnostic inequities suggest both biological and social factors shape who gets long COVID and who gets proper care.

Studies in this issue

Primary sources used for this newsletter.

  1. Long COVID lasts differently in men and women over a year after infection, with related risk factors
    main storyInternational journal of women's health2026-04-22PMID 42017188
  2. Differences in Long COVID diagnosis by sex, race and ethnicity, and insurance type
    key findingPreventive medicine reports2026-04-20PMID 42004523
  3. Reduced oxygen delivery to muscles during moderate exercise in adults with long COVID
    key findingPhysiological reports2026-04-24PMID 42026739
  4. Understanding how COVID-19 may affect the human brain
    key findingBrain pathology (Zurich, Switzerland)2026-04-22PMID 42019647
  5. Sleep Brainwave Patterns Measured in Long COVID Patients
    key findingSleep2026-04-22PMID 42017829
  6. Lasting blood clotting problems and blood vessel damage after COVID-19
    key findingBlood vessels, thrombosis & hemostasis2026-04-20PMID 42004170
  7. Higher blood thickness is linked to nervous system imbalance in long COVID symptoms
    key findingAmerican heart journal plus : cardiology research and practice2026-04-20PMID 42007006

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