The CDC estimates more than a third of coronavirus patients don’t have any symptoms at all, and 40% of virus transmission happens before people feel sick. The figures are part of the agency’s new guidance for mathematical modelers and public health officials and are not supposed to be predictions of how many people could have or contract Covid-19. The CDC has also released mortality figures and scenarios intended to help public health preparedness. Under the most severe of the five scenarios outlined, the CDC lists asymptomatic case fatality ratio of 0.01, meaning that 1% of people overall with Covid-19 and symptoms would die. But some experts say the figures lowball the proportion of people who are succumbing to the disease.