在疫苗研发出来之前，这种病毒使数千人感染。

The virus ___infected thousands of people before a vaccine was developed.

受污染的水源会使人们感染各种疾病。

Contaminated water can ___infect people with various diseases.

这种细菌可以通过开放性伤口使人感染。

The bacteria can ___infect a person through an open wound.