病毒 (bìngdú) means virus. It is composed of 病 (disease) and 毒 (poison/toxin). It is used in medical, scientific, and everyday contexts, such as 感染病毒 (to be infected with a virus).
这种病毒传播速度非常快。
zhè zhǒng bìngdú chuánbō sùdù fēicháng kuài.
This virus spreads very quickly.
科学家正在研究新的病毒变种。
kēxuéjiā zhèngzài yánjiū xīn de bìngdú biànzhǒng.
Scientists are studying new variants of the virus.
你应该勤洗手,预防病毒感染。
nǐ yīnggāi qín xǐ shǒu, yùfáng bìngdú gǎnrǎn.
You should wash your hands frequently to prevent virus infection.