This is why coronavirus may be life-threatening for some patients

The common thread in the research is the lack of a substance called interferon that helps orchestrate the body's defense against viral pathogens

When two brothers fell critically ill with Covid-19 around the same time in March, their doctors were baffled. Both were young -- 29 and 31 years old -- and healthy. Yet within days they couldn’t breathe on their own and, tragically, one of them died.
 

Two weeks later, when a second pair of Covid-stricken brothers, both in their 20s, also appeared in the Netherlands, geneticists were called in to investigate. What they uncovered was a path leading from severe cases, genetic variations, and gender differences to a loss of immune function that may ultimately yield a new approach to treating