Knowing the number of people likely to die, or who get seriously sick or have zero symptoms, will help health authorities determine the strength of the response required. They can better estimate how many isolation beds, heart-lung machines and medicines, among other things, are needed.

Last month, to start understanding the severity of this illness, my team assisted Chinese experts in analyzing the initial 425 confirmed cases of infection. We learned that 65 percent of people had neither visited a market nor been exposed to another person showing pneumonialike symptoms, which implied, among other things, the possibility that some infected people don’t suffer from obvious symptoms — meaning the illness isn’t always severe.

Along with getting a grasp on the level of severity is figuring out susceptibility, or who is most at risk for infection. The data so far indicates that this would include older adults, the obese and people with underlying medical conditions. There are few reports of children becoming infected. But are they not showing symptoms, or are they immune? And could they infect others as silent carriers? We must study those under 18 to find out; the answers could help us fine-tune public health measures. For example, should schools in China and Hong Kong remain closed?

Returning to the big picture, we must also refine what we know about how the new coronavirus is passed between people. Even as the outbreak appears to keep escalating, we believe the rapid — sometimes necessarily draconian — response of governments and health authorities has made a dent in transmission. In another recent study, we estimated how many people could get infected if there were no drastic public health interventions. Our goal with this report was to sound the alarm over what could be, so that it wouldn’t be.

Scientists are working toward quantifying effectiveness of the response. We need to find out if the virus’s basic reproductive number, the R0 or R-naught, has dropped. While our earliest estimates showed that typically every person infected by the new coronavirus passes it to 2 to 2.5 others, it’s still too early to know if measures have reduced the number to below the critical threshold of 1.

Simultaneously, we’re closely watching the rest of the world for any large, sustained outbreaks that might resemble ground zero in Wuhan. We expect more clarity within days or weeks. As of Monday, the largest concentration of infected patients in a single location outside mainland China, at more than 130 people, is on a cruise ship, the Diamond Princess, quarantined at Japan’s Yokohama port.