Because the Emergency use status is a formality applied to many new drugs. It covers the arse of the regulators. It has little real meaning, because they are only approved for emergency use after extensive testing. And the Covid vaccines have now been used on billions of people with no more adverse reactions than is usual with any new drug. There will always be a few people who have a bad reaction to anything. Peanut allergy is a good example, where peanuts are harmless to 99.99% of us but potentially deadly to 0.001% of us.
