医生需要戴口罩以防止感染。

Yīshēng xūyào dài kǒuzhào yǐ fángzhǐ gǎnrǎn.

Doctors need to wear masks to prevent infection.

有些疾病可以通过空气传播感染。

Yǒuxiē jíbìng kěyǐ tōngguò kōngqì chuánbò gǎnrǎn.

Some diseases can be transmitted through the air and cause infection.

他因为与患者接触而感染了病毒。

Tā yīnwèi yǔ huànzhě jiēchù ér gǎnrǎnle bìngdú.

He got infected with the virus through contact with a patient.