President Donald Trump says he is seeking more answers about the death of a Russian worker from plague at a Siberian lab, a case that has ignited public health concerns worldwide.

During an Oval Office event Wednesday, the president was asked by Fox News if the death was the result of “a bioweapon.”

“Well, we don’t think so,” Trump said. “We’re gonna find out soon enough, but we don’t think so, and if you listen to them, it’s under control.”

“We’ve heard this before, a couple of years ago during your first term,” Fox reporter Peter Doocy then asked. “Are you getting the same vibe right now from Russia that you got from China at the start of Covid?”

“Well China didn’t say much, and Russia’s not saying much either, but they do say they have it very much under control,” Trump said. He added that he plans to call Russian President Vladimir Putin later in the day Wednesday, noting it is Putin’s birthday.

Darya Shipilova, a 28-year-old worker at the Irkutsk Research Anti-Plague Institute in Siberia, died Friday from pneumonia of an unknown cause. Authorities subsequently quarantined about 200 people.

Most have since been released, and Russian officials said no plague cases had been detected among Shipilova’s contacts. Officials also said she had been vaccinated and was “immune to ​the dangerous infections with which she worked,” adding there was no risk of an epidemic.

Global health officials have closely monitored the case and called for greater transparency, citing concerns about parallels to the early days of the Covid pandemic, which began with a small number of fatal respiratory illnesses.

World Health Organization chief Dr. Tedros Adhanom Ghebreyesus said Wednesday that a “full risk assessment” has not yet been possible.

He added that “timely, complete and transparent information sharing under the international regulations is essential to clarify conflicting reports and enable an accurate assessment of potential public health risks.”

U.S. Centers for Disease Control and Prevention Director Erica Schwartz said the agency is prepared to screen travelers, though she described the risk to Americans as very low.

The U.S. State Department also warned Moscow this week that its failure to disclose details about Shipilova’s death violated international health obligations, The Wall Street Journal reported.

“Plague infections occur regularly with a few hundred cases a year globally,” Paul Hunter, a professor of medicine at the University of East Anglia, previously told The Independent.

“There are different forms of the disease, bubonic and septicaemic are spread by flea bites from close contact with infected animals,” Hunter said. “Pneumonic plague is spread person to person through respiratory droplets.”