好，介词没问题。我觉得你的提议和原标题在语法上都正确。我上网看了一下，不同的媒体在报道这则消息时用了略微不同的标题。我在

此把他们列出来，或许能帮助你理解。1，Student killed himself after bullying about his vaccination status. 2. Chicago teen committed suicide after ( relentless ) bullying about his vaccination status. 3. Latin School student died after ("increasingly cruel") bullying ignored by adults. 4. Student takes his own life after being bullied over his vaccination status. 5. Student kills himself after （peers mercilessly bully him ）over his vaccination status. 6. Chicago student died by suicide after bullying while school 'turned a blind eye'. 把例2 和例3 括号里的修饰词去掉，就跟例1一样了。把例5里的bully改成现在分词，其它词去掉，也跟例1一样了。例4跟你的想法一致。所以，两者语法上都对。原标题强调事件本身，用动名词，使标题更简捷。例4强调动作，用被动语态，意思更明了。对英语读者来说，两者都不会有太多误解。