Dr Michelle Dickinson: nanotechnologist on what one Covid case taught experts about virus evolution - The Sunday Session with Francesca Rudkin

Most of us have had to take a few days off work or school because of the flu or Covid-19. But imagine being sick with Covid, not for a week or two, but for 750 days! 

That’s exactly what happened to one patient described in a recent paper published in the Lancet (Characterisation of a persistent SARS-CoV-2 infection lasting more than 750 days in a person living with HIV: a genomic analysis - The Lancet Microbe). 

The patient, a 41-year-old man living with HIV, continuously tested positive for Covid-19 for 26 months. Because his HIV was poorly controlled, his immune system was compromised. He had also not been vaccinated against Covid-19 and never received antiviral treatment during his illness. 

While this was an incredibly tough experience for him personally, it offered researchers a rare chance to watch in real time how a virus can evolve inside a single human body. 

Over the course of 750 days, scientists collected eight samples from the patient. From these, they extracted viral RNA and sequenced the virus’s genome. 

They found that: 

• 68 new viral mutations appeared over time. 
• 10 of these mutations were in the spike protein, the part of the virus that helps it enter human cells. 
• Some of these matched the exact changes later seen in the highly transmissible Omicron variant. 

Even more concerning, one alteration made the virus better at evading immune responses. 

The important part of this study in that these mutations showed up in the patient months before they were detected spreading widely in the community. 

This suggests that long-term infections in immunocompromised people can act like mutation incubators, where the virus experiments with new tricks before releasing them into the wider population. 

This case highlights several important lessons: 

• Persistent infections matter: They aren’t just unusual cases. They can directly influence how viruses evolve and have a consequence on the rest of the world. 
• High-risk patients need better support: Improved access to antiretroviral therapy for HIV, vaccination, and Covid-19 treatments can reduce the chances of these prolonged infections. 
• Stopping variant incubation is key: By treating persistent infections early, we may be able to slow down or even prevent the emergence of dangerous new variants. 

This story is a sobering reminder that pandemics don’t just happen on a global stage, they can begin quietly, inside the body of a single individual. For scientists, these unusual cases are windows into viral evolution. For the rest of us, they underscore why protecting vulnerable groups isn’t just compassionate, it’s critical for everyone’s health. 

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