- "The number of new infections is being kept low."
"the number of ~" 「〜の数」
"new infections" 「感染者」"infected people" も言えます。
"is being kept ~" 「〜て抑えられています」
"low" 「低く」
"is being kept low" 「低く抑えられています」"is being contained" や "is being kept under control" も使えます。