Coronavirus has killed more than 40,000 people in the United States, Johns Hopkins University reports.

On Sunday, the national death toll surpassed 40,500 people, a data tracking site maintained by the university reported.

There have been 2.3 million confirmed cases of the COVID-19 virus worldwide, with more than 164,000 deaths, according to the university. More than 23,000 people have died in Italy, and more than 20,000 in Spain.

The United States has had more than 742,000 confirmed cases, and 3.7 million people in the U.S. have been tested for the COVID-19 virus, Johns Hopkins University reported.

The U.S. Centers for Disease Control and Prevention estimates that the seasonal flu has killed from 24,000 to 62,000 people nationally in 2019-2020. A 2009 swine flu pandemic killed more than 12,000 people in the United States.

Surgeon General Jerome Adams said a plan unveiled Thursday by the federal government to roll back some coronavirus lockdown orders relies on testing and contact tracing, Fox News reported.

“You are slowly starting to go back to work. You are slowly starting to go back to movie theaters and restaurants with social distancing,” Adams said, according to the network.

“And, one of the things I want the American people to know is that we do expect that there will be setbacks in some places,” Adams said, Fox News reported. “But, one of the criteria is making sure you have the ability to quickly detect these setbacks and respond to them so that one case doesn’t become a thousand cases.”

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said coronavirus will remain a threat until there’s a vaccine, Rolling Stone reported.

“It’s not going to be over to the point of our being able to not do any mitigation, until we have a scientifically sound, safe, and effective vaccine,” Fauci said, according to the publication.

“It’s an extraordinarily efficient virus in transmitting from one person to another,” Fauci said, The Hill reported “These kinds of viruses don’t just disappear.”

The coronavirus outbreak began in December in Wuhan, China, possibly after the virus passed to humans from bats and pangolins, an Asian scaly anteater, McClatchy News reported.

COVID-19, named because it is a new type of coronavirus first seen in 2019, comes from a family of viruses responsible for the common cold, SARS, MERS and other ailments.

The World Health Organization has declared coronavirus a global pandemic. In the United States, President Donald Trump has declared a national emergency.