The Centers for Disease Control and Prevention has issued new guidelines for health officials and mathematical modelers that now estimate roughly 40% of all people infected with COVID-19 are asymptomatic.
At the end of May, 35% of COVID-positive cases resulted in no symptoms, but new testing data has pushed that number higher.
The CDC has also begun to take into account asymptomatic cases of COVID-19 when calculating the infection fatality rate (IFR), where previously that figure was calculated using only symptomatic cases. The new numbers suggest the infection fatality rate for COVID-19 is as low as 0.65%, meaning fewer than 1% of those infected are likely to die.
The CDC was careful to point out that these are only guidelines and that involving asymptomatic cases is difficult because there is greater inability to identify positive cases and "transmission is difficult to observe and quantify."