An infant in the United States has died from Covid-19, officials in the state of Illinois said on Saturday, March 28.

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

This marks an extremely rare fatal case as a result of the pandemic.

Governor JB Pritzker said during a press conference that "an infant" was among the fatalities linked to the new coronavirus over the previous 24 hours.

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."

The case is being investigated to determine what had happened.

"A full investigation is underway to determine the cause of death," the public health department's director Ngozi Ezike said in a statement.

"There has never before been a death associated with Covid-19 in an infant."

Covid-19 has disproportionately affected the older population.

Teenager died previously

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

But the agency added the case is complex and there may be an alternate explanation.

More than 450 US deaths occurred over the 24-hour period prior to Saturday afternoon.

The Chicago baby was among 13 new deaths in Illinois.

At more than 120,000, the US has the highest number of new coronavirus cases in the world.

But its death toll of more than 2,000 is still below that of other countries including Italy, Spain and China.