It's because he was immunosuppressed, and most other people aren't.

那是因为他的免疫受到了抑制，但一般其他人并没有。

Because DD is immunosuppressed, his immune system, mainly his white blood cells, have reduced activity.

由于DD的免疫系统是被抑制的，他的免疫系统，也就是大部分的白血球，其活性是被减弱的。

And that has to do, of course, with your underlying medical conditions whether or not you're immunosuppressed whether or not you've been vaccinated and boosted.

当然，这与你的潜在健康状况有关，不管你是否受有免疫抑制，也不管你是否接种过基础疫苗或加强疫苗。