Generally normal phones won’t get any threat of virus attack so no need to worry but if I gave rooted your phone if you install any mallware application your phone data may get lost our your phone may not work.
You have to make sure that you install apps from trusted sources.
In this case i.e. If your phone is rooted you may have to consider a mobile antivirus software.
Until your phone is not rooted your are safe since every android has a antivirus software built in.
If you root it the antivirus software built in will not work