SH2D3A and early-onset autosomal dominant Alzheimer disease: We discovered that Nsp1, a viral protein encoded by SARS-CoV-2, the virus causing the ongoing COVID-19 epidemic, ameliorates neuromuscular degeneration in fly models of Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis, which share a common mechanism—accumulation of aberrant protein species due to stalling and collision of ribosomes—which is resolved by Nsp1.