Stony Brook, New York – A "staggering" 40,000 children in the US have lost at least one parent to coronavirus, three-quarters of them teenagers, a new model has calculated.

Researchers at Stony Brook University on Long Island estimated the number of children of each adult to have died of Covid-19 and extrapolated to arrive at that conclusion.

The model suggested that each such death left 0.078 children between infancy and age 17 "parentally bereaved," the researchers said in a letter published in JAMA Pediatrics, 17.5% to 20.2% more than it would have been without Covid-19.

"Although the bereavement multiplier is small, it translates into large numbers of children who have lost a parent," wrote Rachel Kidman of the Program in Public Health at Stony Brook University. "As of February 2021, 37,300 children aged 0 to 17 years had lost at least 1 parent due to COVID-19, three-quarters of whom were adolescents."

Judging by excess deaths overall, the estimate goes even higher – to 43,000 children who’ve lost a parent in the past year.

Beyond the grief of losing a parent during one’s formative years is the difficulty of supporting the bereaved children during this time of heightened social isolation, as the pandemic drags on. Further, the authors said, deaths will mount, which means even more children will suffer this loss.

In comparison, she noted, the September 11, 2001, attacks led to 3,000 children losing a parent.

"The number of children experiencing a parent dying of COVID-19 is staggering," Kidman wrote. "The burden will grow heavier as the death toll continues to mount."

Moreover, Black children are disproportionately affected, given that they comprise 14% of US children but 20% of those who have lost a parent to Covid-19, the letter said.

The paper, based as it is on estimates built on demographic modeling rather than data from a survey or statistical information, is painting a broad, inexact picture, Kidman noted. It also does not include primary caregivers who were not a child’s parents.

She and her co-authors called for "sweeping national reforms" to support children who are in this situation.

The impact of even one set of parents dying of Covid-19 on teens was evident in the lives of Nathan and Isaih, two teenagers who are now being raised by their grandmother after both their parents died of Covid-19 last July, as CBS News reported at the time.

"What makes deaths from Covid more challenging than, say, if somebody passed away of old age, is that the deaths related to Covid may lead to child traumatic grief, which is different than just grief itself," psychologist and professor at Duke University Medical Center Robin Gurwitch told CNN.

"The normal activities related to death cannot happen, so a child that’s lost someone right now, no matter what the circumstances, but particularly due to Covid, make it so much more challenging because all the things that I would normally do, I can’t do, the family can’t do."