Probably because the covid issue evolved gradually. First we knew that something was happening in China but couldn't tell what it was exactly, then we realized

Probably because the covid issue evolved gradually. First we knew that something was happening in China but couldn't tell what it was exactly, then we realized it was a decease but didn't know how bad, then there was the lockdown but information from China is regulated so no big story here, and then it hit Europe and all hell broke loose. The thing is that there wasn't a singular event that would have captured all of our attention catapulting it to the top of HN.