Belgian authorities say a 12-year-old girl has died of the coronavirus, by far the youngest person among the more than 700 victims in the country. Dying from the virus at such a young age "is a very rare occurrence," said government spokesman Dr Emmanuel Andre, adding that her death "shook us".

The girl had had a fever for three days before her death, and tested positive for COVID-19, said another spokesman, Steven Van Gucht.

Andre said it is "an emotionally difficult moment, because it involves a child, and it has also upset the medical and scientific community."

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"We are thinking of her family and friends. It is an event that is very rare, but one which upsets us greatly," Andre said.

No other details were given about her case, including whether she had any other underlying health problems.

It was the first death of a child in the coronavirus crisis in Belgium, which has now recorded a total 705 deaths from the disease it causes, according to the latest official toll.

Last week, France reported the death of a 16-year-old girl from coronavirus in the greater Paris region.

Although serious COVID-19 infections are uncommon among the young, some exceptional cases have been taken to hospital intensive-care wards, as US health authorities have pointed out.

Belgium's toll on Tuesday represented a jump of nearly 200 fatalities from that given the previous day, which stood at 513.

It comprised 98 deaths recorded in the preceding 24-hour period, plus another 94 deaths over previous days but which had not been counted in the national tally, Andre said.

A member of the medical staff, wearing full protective equipment, helps a co-worker to remove her protective suit in the triage area of the polyclinic Klinicare during a partial lockdown against the spread of Covid-19 in Brussels, March 30, 2020. Francisco Seco / AP

In the U.S., Chicago reported what is believed to be the first infant to die from the coronavirus. The medical history of the baby was not immediately released, but an investigation into their death is underway, and a doctor says it's a "very unusual" case.

Chicago Department of Public Health Commissioner Dr. Allison Arwady, said the high risk for COVID-19 is still in elderly populations and people with preexisting conditions.

"It's very unusual to be seeing a case like this, so obviously we're doing a thorough investigation, working really with the family, our hearts go out to them, the pediatrician, the medical examiner, the CDC, really wanting to make sure we're doing confirmatory testing, looking at everything that's underlying it," she said on "CBS This Morning" Monday. "We're obviously concerned about it, but by and large, the main risk does remain in the older populations, the folks with the underlying medical conditions."