Director of the US Centers for Disease Control and Prevention (CDC) Robert Redfield attends a press conference on the COVID-19 at the White House in Washington DC March 9, 2020. Photo:Xinhua

Some flu-related deaths in the United States may have connections with the novel coronavirus after community transmission was confirmed, a leading US epidemiologist said on Thursday.

"After the first case of community spread in the United States was confirmed at UC (University of California) Davis Medical Center, those patients who died of influenza may have links with COVID-19," said Zhang Zuofeng, professor of epidemiology and associate dean for research at the School of Public Health at the University of California, Los Angeles.

Some COVID-19 deaths have been diagnosed as flu-related in the United States, Robert Redfield, director of the Centers for Disease Control and Prevention (CDC) said on Wednesday.

Redfield made the remarks when responding to a question at a hearing about whether people in the United States dying of what appears to be influenza could in fact be infected with the coronavirus.

"Some cases have been actually diagnosed that way in the United States to date," Redfield said.

Due to the lack of coronavirus tests in the United States, many patients who died of influenza haven't been tested to see whether they were also infected with the coronavirus, Zhang told Xinhua.

A member of National Guard distributes food to qualified residents near the one-mile-radius containment area in New Rochelle, New York State, the United States, on March 12, 2020. The US state of New York set up a so-called "containment area" in a COVID-19 hotspot on Thursday, with National Guard troops dispatched on site to clean surfaces and deliver food to people who are in quarantine. Photo:Xinhua

But before community transmission was confirmed in the United States in late February, those flu-related deaths may not be caused by coronavirus, added Zhang.

"As the coronavirus is highly contagious, if those flu patients were infected with the coronavirus, we could have many medical staff infected as well. But we did not see this case," he said.

US authorities have come under fire for carrying out far fewer tests than many other affected countries. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said that the country's coronavirus testing system is "failing."

As of Wednesday night, more than 1,300 coronavirus cases have been reported in the United States with 38 deaths, according to real-time data maintained by the Center for Systems Science and Engineering at Johns Hopkins University.