Covid was mutating, that's why the advice kept changing. Vaccines were 80% effective, than immune escape happened and the vaccines got less effective. At the sa

Covid was mutating, that's why the advice kept changing. Vaccines were 80% effective, than immune escape happened and the vaccines got less effective. At the same time, covid was getting better at spreading, which is why 2 weeks to flatten the curve wasn't enough. It's not a bad thing for experts to change their opinion as new evidence comes out.