上海疫情事件脉络:奥密克戎BA.2为何击穿防线?奥密克戎BA.2疫情挑战,上海防线为何被击穿
The context of the Shanghai epidemic: Why did Omicron BA.2 break through the Defense line? Why has Shanghai's defense line been breached amid the challenges posed by the Omicron BA.2 outbreak
以上为机器翻译结果，长、整句建议使用 人工翻译 。