vaccine

流感疫苗已经用完了。

Doctors have run out of the flu ___vaccine.

许多诊所的季节性流感疫苗已经用完了。

Many clinics have run out of the seasonal flu ___vaccine.

这种新疫苗在临床试验中被证明非常有效。

The new ___vaccine has proven highly effective in clinical trials.