More on how under-rated our sense of smell is – and how loss of smell can be an early indicator of COVID-19. In your DNA many of the genes associated with smell are located right next to a big bunch of genes that form your immune system. As a baseline, pre-COVID-19, about 1-5% of the general population had no sense of smell, and another 5-13% had a lessened sense of smell. But COVID-19 has bumped these percentages way up.