By CBS3 Staff

MONTGOMERY COUNTY, Pa. (CBS) — The CDC says laboratory testing shows vials marked as “smallpox” at a Merck facility in Montgomery County contain no trace of the virus known to cause smallpox.

Officials say the vials contain vaccinia, the virus used in the smallpox vaccine.

A worker discovered the vials while cleaning out a freezer.

The CDC says no one was exposed to the contents of the vials.