A medical worker wearing a protective mask and glasses at the Oglio Po hospital in Cremona, Italy, March 19, 2020 (Flavio Lo Scalzo/Reuters)

Last updated March 19, 5 P.M. EST

As the coronavirus pandemic grips the world, observers are closely tracking the trajectory of confirmed cases to forecast its spread in the coming months. In the U.S., the number of confirmed cases continues its steep upward trajectory, in large part due to delayed testing, which has given an incomplete picture of the domestic outbreak. In Italy, the growth rate of cases shows no signs of abating either, even as the country overtakes China as the global epicenter of the pandemic. Other countries, most notably South Korea and Singapore, have succeeded in “flattening the curve” through robust testing and social distancing.

Italy has overtaken China as the country suffering the largest death toll from coronavirus, with Iran and Spain seeing similar numbers of dead. The devastation in Italy has been attributed to its large portion of elderly citizens and its slow response to the crisis. In Iran, numerous government officials have contracted the illness, 12 of whom have died. Iranian President Hassan Rouhani only recently closed religious sites. The virus has killed 160 Americans, spurring the White House and state governments into measures aimed at social distancing and increased testing.

In the U.S., a slow rollout of diagnostic tests initially left authorities ill-equipped to combat the crisis. New York has been the hardest hit, with over 4,000 confirmed cases. New York City has more or less shut down after Governor Andrew Cuomo ordered restaurants, bars, and entertainment venues to close their doors on Monday. California and Washington, which have also become domestic epicenters of the outbreak, have taken similar measures.

Private and academic labs have largely made up for the initial lack of testing capacity in the U.S. On March 19, more than 25,000 Americans were tested for the virus, bringing the total number of tests administered in the U.S. to just over 100,000. That figure still lags South Korea and China, which have each administered more than 300,000 tests. As more Americans get tested, we can expect a steep increase in cases in the coming weeks and months. Increased testing will allow public-health officials to identify clusters and roll back the extreme social-distancing measures taken over the past week.