The coronavirus that causes COVID-19 can infiltrate star-shaped cells in the brain, setting off a chain reaction that may disable and even kill nearby neurons, according to a new study. The star-shaped cells, called astrocytes, perform many roles in the nervous system and provide fuel to neurons, which transmit signals throughout the body and brain. In a lab dish, the study found that infected astrocytes stopped producing critical fuel for neurons and secreted an "unidentified" substance that poisoned nearby neurons.