By Pat Anson, PNN Editor

About 16 million people in the United States have Long Covid, a poorly understood disorder that causes body aches, headaches, fatigue, insomnia, brain fog and other symptoms long after an initial infection with COVID-19. For some, the symptoms are mild, but for other they are so severe they become disabling.

Why do some people quickly recover from Covid, while about one in five have lingering symptoms?

A new animal study found that thousands of genes involved in nervous system function are affected by SARS-CoV-2, and may cause lasting damage to dorsal root ganglia, the spinal nerves that carry pain and other sensory messages to the brain. Scientists believe that genetic damage may be what causes Long Covid.

“Several studies have found that a high proportion of Long Covid patients suffer from abnormal perception of touch, pressure, temperature, pain or tingling throughout the body. Our work suggests that SARS-CoV-2 might induce lasting pain in a rather unique way, emphasizing the need for therapeutics that target molecular pathways specific to this virus,” explains co-author Venetia Zachariou, PhD, chair of pharmacology, physiology & biophysics at Boston University’s Chobanian & Avedisian School of Medicine.

Zachariou and her colleagues infected hamsters with SARS-CoV-2 and studied how it affected the animals’ sensitivity to touch, both during the initial infection and after the infection had cleared. Then they compared the effects of SARS-CoV-2 to those triggered by an influenza A virus infection, and were surprised by what they found.

In the hamsters infected with Covid, researchers observed a slow but progressive increase in sensory sensitivity over time – one that differed substantially from influenza A infections, which caused a sudden hypersensitivity that returned to normal once the initial infection ended.

Although the studies were performed on animals, researchers say they align with the acute and chronic symptoms caused by Covid in humans. They hope further studies on human genes and sensory pathways affected by the Covid virus will lead to new treatments for Long Covid and conditions such as ME/CFS (myalgic encephalomyelitis/chronic fatigue syndrome),

“We hope this study will provide new avenues for addressing somatosensory symptoms of long COVID and ME/CFS, which are only just now beginning to be addressed by mainstream medicine. While we have begun using this information by validating one promising target in this study, we believe our now publicly available data can yield insights into many new therapeutic strategies,” adds Zachariou. 

The study findings appear online in the journal Science Signaling.

The federal government’s Covid public health emergency officially ends this week, but the impact of the pandemic will likely be felt for years to come.