Everyone else has had good answers, but I'm also going to note that we knew a ton about covid's general molecular biology well before it ever came into existence. Covid (more properly, SARS-CoV-2) is a cronovirus. Cronoviruses have been studied for some time since some of them cause common colds, and studied very intensely since 2002 when SARS showed pandemic potential. So when Covid showed up, there was a ton of prestablished information and expertise avaliable to help every element of the pandemic response.