They aren’t perfect.
Not at all. How many people experience long-term crippling effects from the flu?
BTW, the care we are taking has reduced the number of flu cases too.
And even if it were just a flu for you, there’s a 3% chance each person you infect will die a horrible death after a month of agony.
COVID is still new, while flu has been with us for millenia. Give it time and opportunities and it'll perfect itself.
3% is too high.