For millions around the globe, the pandemic never really ended. It just morphed into something worse: long COVID. The symptoms read like a medical nightmare. Crushing fatigue. Brain fog so thick you can’t remember your own phone number. Breathlessness that makes a flight of stairs feel like Everest. Up to 400 million people worldwide are dealing with this, and we still don’t know why it happens or how to treat it.
But a team of 17 microbiologists, including experts from Rutgers Health, think they’ve finally found the missing piece. Their new review in eLife offers a radically different explanation: co-infections. Not just new bugs you pick up, but old ones. Pathogens your body locked away years ago, now shaken awake by COVID-19’s assault on your immune system.
The idea redirects the entire investigation. SARS-CoV-2 might not be the only villain in this story. Instead, picture a volatile microbial gang, with multiple pathogens exploiting an immune system left weakened and thoroughly confused. If this theory holds up, existing antibiotics and antivirals could be quickly repurposed to target these hidden invaders. No need to invent new drugs from scratch.
When Sleeping Viruses Wake Up
The most compelling evidence centers on Epstein-Barr virus. EBV causes mono, the kissing disease that wrecks college dorms every fall, and roughly 90% of adults carry it dormant for life. It just sits there, quiet. Until something massive shocks the immune system.
Early studies showed that about two-thirds of long COVID patients had signs of recent EBV activity. Not only that: patients with worse long COVID symptoms showed higher antibody levels against the reactivated virus. Later research tied EBV directly to the signature symptoms, cognitive impairment and relentless fatigue.
Then there’s tuberculosis. About a quarter of the world harbors latent TB bacteria. COVID-19 appears to deplete the specific immune cells that keep TB locked down, giving the bacteria a chance to reactivate. It’s a vicious feedback loop. An unnoticed TB infection might worsen your acute COVID outcome, while COVID simultaneously increases your TB reactivation risk.
Maria Laura Gennaro, a microbiologist at Rutgers who chaired a key NIH task force, sees this as a blind spot in long COVID research.
This is an aspect of long COVID that is not talked about a lot, Gennaro said.
The timing of these infections matters enormously. One before COVID may have already weakened your defenses. One during the acute phase compounds the organ damage. One after simply exploits the lasting immune chaos. You can picture SARS-CoV-2 not as a single explosion but as a scorched-earth campaign, leaving deep structural weakness in the body’s defenses. The suffering isn’t just from the original virus. It’s from the opportunistic microbes that followed.
Immunity Theft and What Comes Next
Here’s where it gets alarming. The researchers point to a global trend: 44 countries have reported tenfold spikes in at least 13 infectious diseases compared to pre-pandemic levels. They’ve coined a term for this, “immunity theft.” The idea is simple but unsettling. After recovering from acute COVID, you enter a period of drastically heightened vulnerability to other infections.
SARS-CoV-2 doesn’t just cause flu-like symptoms and move on. It confuses the entire immune system, driving chronic inflammation in the lungs, heart, and brain. In this disarray, your body can’t maintain its prison on old enemies like EBV. It can’t mount adequate defenses against new bacterial or fungal threats either.
If the co-infection theory proves accurate, the treatment hunt becomes dramatically more efficient. Antivirals that target reactivated herpes viruses. Antibiotics for bacterial pathogens like TB. These drugs already exist, already passed safety trials. The goal: eliminate the secondary infection and see if the debilitating long COVID symptoms finally fade.
The authors remain cautious, though. Rigorously so. The associations they’ve detailed are biologically plausible, sure. They make medical sense. But they’re still speculative. No one has established a definitive causal link between any single co-infection and persistent long COVID.
Gennaro offered the necessary scientific warning:
Correlation doesn’t equal causation, Gennaro said.
Proving this hypothesis demands massive epidemiological studies tracking patients over years. It requires complex animal experiments, which remain particularly challenging because scientists lack models that accurately mimic the full spectrum of long COVID in humans.
For the millions still suffering, this review offers no instant relief. But if a truly effective treatment emerges, it will likely come from looking past the initial viral infection and turning attention to the microbial shadows it unexpectedly roused.
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More likely though Long Covid occurs as a result of an explosion of spike proteins that is shutting down ACE2 receptors in multiple organs.
This is amazing! Please try to find treatments for long covid as alot of us are suffering from this and it’s creating so much havoc. We just want our lives back. Doctors have no clue how to treat us let alone even acknowledge that long covid is an actual condition.