A U.S. infant has died from the COVID-19 illness, officials in the state of Illinois said on Saturday, marking an extremely rare case of juvenile death in the global pandemic.

At a news conference, Gov. J.B. Pritzker said an "infant" was among the fatalities linked to the new coronavirus over the previous 24 hours.

The state Department of Public Health said the child who died in Chicago was younger than 1-year-old and had tested positive for COVID-19.

"There has never before been a death associated with COVID-19 in an infant," the department's director, Ngozi Ezike, said in a statement. "A full investigation is underway to determine the cause of death."

Pritzker described himself as shaken by the news. "I know how difficult this news can be, especially about this very young child," he said. "It's especially sorrowful for the family of this very small child, for the years stolen from this infant. We should grieve."

Last week, the reported deaths of three young people with no preexisting health conditions from COVID-19 in the U.S., the U.K. and France have raised safety warnings. A top French health official Jerome Salomon said on Friday a 16-year-old girl had died in Paris.

"Severe forms (of coronavirus) with the young are very rare," Salomon noted.

A 21-year-old woman was reported dead on Wednesday from the disease caused by the coronavirus despite having no underlying health conditions.

In the U.S. state of California last week, the Los Angeles County Department of Public Health said that a teenager had tested positive for COVID-19 and died.

Young people are not immune from the coronavirus and must avoid socializing and communicating it to older, more vulnerable people, the World Health Organization (WHO) has warned.