The dormant viruses in all of us may help explain long COVID

Summary of The dormant viruses in all of us may help explain long COVID

by NPR

14m•October 23, 2026
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Overview of The dormant viruses in all of us may help explain long COVID

This NPR Short Wave episode explores how common dormant viruses—especially herpes-family viruses like Epstein-Barr virus (EBV), cytomegalovirus (CMV), and varicella-zoster virus (which causes chickenpox and shingles)—can reactivate under stress, illness, aging, or immune disruption. Immunologist Akiko Iwasaki explains how research, including an unexpected NASA astronaut study, is helping scientists understand viral reactivation and why it may be relevant to long COVID, autoimmune disease, and other chronic conditions.

Key Takeaways

  • Many people carry dormant viruses for life.

    • Examples include:
      • Varicella-zoster virus (VZV) — causes chickenpox and can later reactivate as shingles.
      • Epstein-Barr virus (EBV) — linked to mononucleosis and associated with other diseases.
      • Cytomegalovirus (CMV) — also extremely common.
    • These viruses can remain latent without causing symptoms for years.

  • Dormant viruses can reactivate even in healthy people.

    • A NASA study of astronauts found that spaceflight stress could trigger reactivation of multiple dormant viruses at once.
    • This surprised researchers because the astronauts were otherwise healthy.

  • Reactivation isn’t limited to spaceflight.

    • Stressors on Earth—especially severe infection, immune suppression, major physical or mental stress, aging, or certain drugs—can also allow dormant viruses to wake up.
    • Mild day-to-day stress is not usually enough to cause major reactivation in younger people.

  • Herpesviruses are especially good at hiding from the immune system.

    • These ancient viruses evolved alongside humans and are skilled at turning off their detectable signatures so the immune system does not eliminate them.
    • They can also shed virus without obvious symptoms, meaning a person may feel fine and still be contagious.

Long COVID and Viral Reactivation

Possible connection to EBV

  • The episode highlights growing evidence linking EBV reactivation to long COVID.
  • Scientists think COVID-19 may:
    • directly persist in some tissues,
    • trigger reactivation of dormant viruses like EBV,
    • or contribute to autoimmune-type reactions.

Related autoimmune links

  • EBV is already strongly associated with:
    • multiple sclerosis
    • lupus
  • Researchers suspect that in some cases, immune responses to EBV may lead the body to attack its own tissues.

What this means for long COVID research

  • Long COVID may not have a single cause.
  • Instead, it may involve a domino effect:
    1. initial COVID infection,
    2. immune disruption or lingering virus,
    3. reactivation of dormant viruses,
    4. inflammation or autoimmunity,
    5. ongoing symptoms.

What Scientists Still Don’t Know

  • The episode emphasizes that long COVID is not fully understood.
  • Open questions include:
    • Which mechanism is driving symptoms in a given patient?
    • How much of long COVID is caused by persistent SARS-CoV-2 vs. reactivated viruses vs. autoimmunity?
    • Why do some people recover while others develop long-term illness?

Treatment and Prevention Implications

  • Better diagnostics could help identify which biological processes are active in each patient.
    • That would allow more targeted treatment instead of one-size-fits-all care.
  • Stronger antivirals for latent viruses are still needed.
  • Vaccines may be important:
    • There is a vaccine for chickenpox/VZV.
    • There are no vaccines yet for several other herpesviruses like EBV.
  • For older adults, the shingles vaccine is strongly recommended because age increases the risk of VZV reactivation.

Notable Insight

  • Akiko Iwasaki frames the relationship between viruses and the immune system as an “arms race”:
    • viruses evolve to evade immune detection,
    • while scientists are still learning how they do it.

Bottom Line

The episode argues that dormant viruses are more than a background curiosity: they may be an important piece of the puzzle in long COVID and other chronic illnesses. While most healthy people do not need to worry about these viruses day-to-day, the research suggests that understanding viral reactivation could lead to better diagnostics, treatments, and preventive vaccines.