IPA: /ˌæntɪˈdʒɛnɪkli/
KK: /æntɪˈdʒɛnɪkli/
In a way that relates to an antigen, which is a substance that triggers an immune response in the body.
The vaccine works antigenically to help the body recognize and fight the virus.
Antigenically → It is formed from "anti-" (meaning against) and "gen" (from Greek "genes", meaning born of or produced by) and the suffix "-ic" (meaning pertaining to) and "-ally" (meaning in a manner). The word describes something that pertains to the production of substances that act against foreign substances in the body.
Think of 'against' ('anti-') and 'produced by' ('gen') to remember that 'antigenically' refers to how something relates to substances that act against foreign invaders.