A virus is a small organism that attaches to a cell and causes diseases and infections. A virus is passed from one person to another through physical contact, but it can also be transmitted through the air or through the bite of an insect.
A deadly outbreak of the Ebola virus in Liberia caught the attention of the entire world last year.
A flu virus can spread easily, so it’s a good idea to get a flu shot as protection from the virus.
To protect yourself and others from viruses, it’s important to wash your hands frequently.
Disinfectants can kill viruses.
His stomach flu was caused by a virus.
A virus is also a problem for computers and mobile technology.
Donna’s computer has a virus.
If you aren’t careful about what you download from the internet, your computer can become infected with a virus.
Virus protection is available for your computer.
A virus tries to get into your computer.
If a virus finds its way into a computer that is unprotected, it can do a lot of damage to the files on your hard drive.
The word "viral" is often used when describing the sudden popularity of a video, a song, or a website on the internet. In this case, going viral is good.
Thomas posted a cat video on YouTube and it went viral.
Isabel produced an app that went viral and made over $50,000 on it.
If Joe’s website goes viral, he said he would quit his job and focus on producing websites and mobile apps.
His stomach flu was caused by a virus. 
