Pfizer and BioNTech are preparing to start clinical trials of a version of their Covid-19 vaccine targeting the Delta variant next month, amid fears that existing jabs will offer less protection against the infectious strain spreading quickly across much of the world.
辉瑞(Pfizer)和BioNTech准备下月对专门针对Delta变种的新冠疫苗开展临床试验。人们正在担心，现有疫苗对这种在manbetx app苹果 各地迅速传播的强传染性毒株的保护力下降。
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