A new study that researchers conducted in animal models suggests that SARS-CoV-2, the virus that causes COVID-19, may deactivate a pain signaling pathway. This could explain why so many cases of the infection do not cause any symptoms, promoting viral transmission.
Estimates vary widely, but according to the Centers for Disease Control and Prevention’s (CDC) current best estimates, 40% of people with COVID-19 may experience no symptoms.
These people may carry on with their daily activities as usual, without necessarily realizing that they have contracted the virus. This may cause them to spread it unintentionally. For this reason, some scientists refer to people without symptoms as “silent spreaders.”
The CDC also estimate that up to 50% of all SARS-CoV-2 transmission occurs before the onset of symptoms.