为一篇英文新闻稿件提供一段简短的中文总结。以下是一个例子：将一篇关于新冠疫苗的英文新闻稿件总结成一段中文概述。


In a new study, researchers found that the Pfizer-BioNTech COVID-19 vaccine is effective against the delta variant in people who have received two doses. The study, which has not yet been peer-reviewed, involved nearly 4,000 participants.
一项新研究发现，在接种两剂辉瑞-BioNTech的COVID-19疫苗后，该疫苗对Delta变异株的效果显著。此研究涉及近4000名参与者，尚未经过同行评审。