Dr. Fauci said his daughter's boyfriend's brother died from COVID-19 at age 32

• Dr. Anthony Fauci said his daughter's boyfriend's brother died from COVID-19 at age 32.
• "So there you have a 32-year-old young man, otherwise healthy actually, quite athletic and strong, who died," he told CNN's Dr. Sanjay Gupta during a talk for the Harvard T.H. Chan School of Public Health.
• The man developed an unusual heart complication related to the virus that led to his death, Fauci said.

Dr. Anthony Fauci's youngest daughter, Alison, is grieving the loss of her boyfriend's brother, a 32-year-old who died from COVID-19.

"My youngest daughter's boyfriend's brother is a 32-year-old young man, athletic, healthy, who got COVID-19, and had one of the unusual complications of cardiomyopathy with an arrhythmia and died," the nation's top infectious disease expert told Dr. Sanjay Gupta, CNN'S chief medical correspondent, during an interview Wednesday hosted by the Harvard T.H. Chan School of Public Health.

The death is a tragic example of how the virus can affect anyone, no matter their age or health status. "So there you have a 32-year-old young man, otherwise healthy actually, quite athletic and strong, who died," Fauci said.

One October study found that in some areas of the US, coronavirus deaths among 25- to 44-year-olds surpassed rates of opioid overdose deaths, which are usually the leading cause of death among that age group.

Outside of clear causes like serious underlying conditions, Fauci said he still doesn't know why some people like Alison's boyfriend's brother get seriously ill or die, while most others do fine.

"The mystery that haunts me [is] the idea that you have a virus that in most people is almost harmless, ... then in those who get symptoms, most people don't get severe symptoms, and then in another subgroup, inexplicably, makes them so sick that you get 280,000 deaths in the United States," he said.

"There has to be motivation enough for at least most of the people to adhere to the public health issues and public health recommendations that we make," he added.

Fauci did not name Alison's boyfriend's brother, or reveal when he became sick and died.

The coronavirus can damage the heart even in patients without previous heart conditions

Cardiomyopathy is a heart muscle disease that can lead to heart failure. Arrhythmias are heart-rhythm disorders.

Studies have shown that the coronavirus can damage the heart, even among patients like Alison's boyfriend's brother who presumably had a healthy heart before contracting the virus.

One study of 187 Chinese patients with COVID-19 found that nearly 30% experienced heart damage leading to cardiac dysfunction and arrhythmias.

Another study including data from 69 countries and including 1,261 coronavirus patients found that 55% had abnormally functioning hearts. About 1 in 7 patients showed "severe abnormalities," which seemed to have a significant impact on their likelihood of survival and recovery.

"Damage to the heart is known to occur in severe flu, but we were surprised to see so many patients with damage to their heart with COVID-19 and so many patients with severe dysfunction," professor Marc Dweck, a consultant cardiologist at the University of Edinburgh who helped lead the research said, according to the British Heart Foundation.

"We now need to understand the exact mechanism of this damage, whether it is reversible and what the long-term consequences of COVID-19 infection are on the heart."