Probably not a bad batch as much as the recipients were likely allergic to egg yolks, a key ingredient. There are warnings about allergic reactions which can cause Bell’s palsy or other issues.
Had a flu shot many years ago and my arm swelled, turned red, and I got the flu, was told never to take one again. Had a tetanus shot years ago, arm swelled, turned red, told never to take one again. I don’t take a flu shot due to that and stay close to home during flu season and wash my hands a lot during that time.