“Zombie” COVID particles may be responsible for lethal disease
Following the emergence of SARS-CoV-2 in 2020 there are now seven different coronaviruses known to infect humans. Four of those are associated with generally harmless common respiratory infections, but the other three (SARS, SARS-CoV-2 and MERS) are much more dangerous.
Why some coronaviruses are relatively harmless while others are incredibly lethal is still a bit of a mystery. Some answers lie in the proteins each individual virus uses to enter human cells, but what exactly makes SARS-CoV-2 so severe in some people and innocuous in others is unclear.