Many of the more common viruses morph or change frequently to make them more difficult to detect. Viruses spread rapidly and by many different ways (for example, via email attachments; infected document files Web sites that contain hostile code that can infect your computer through vulnerable browsers; and unprotected fileshares). Your computer may be vulnerable to virus attacks if you are not using antivirus software and updating it regularly.
Using AntiVirus and configuring it to update virus definitions automatically will help keep your computer protected.
Always be sure you have the best, up-to-date security software installed to protect your computers, laptops, tablets and smartphones.