LC16m8 (‎live-attenuated freeze-dried vaccinia)‎ smallpox and mpox vaccine: interim guidance, 22 April 2025

Overview

LC16m8 vaccine (also known as LC16 or LC16 KMB) was developed as a third generation smallpox vaccine and more recently licensed for use against mpox. It is a freeze-dried live-attenuated, minimally replicating vaccine containing the LC16m8 strain derived from the Lister strain of vaccinia virus (one of the strains that enabled global smallpox eradication) grown in cell culture by passaging multiple times. The process of multiple passage in cell culture or live animals enhances safety. In contrast to non-replicating vaccines, such as the modified vaccinia Ankara strain (e.g. MVABN), LC16m8 vaccine produces a vaccine-related localized cutaneous reaction – known as a “take” in a vaccine recipient. It presents as an evolving local skin reaction, initially appearing as erythema and induration, which then progresses to blisters and crusting at the vaccination site. 2 A “take” has been used as an “indicator” of successful vaccination.