<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>In medicine, refers to a vaccination given after a previous vaccination. A booster helps maintain or increase a protective immune response.</n0:def-definition><n0:def-source>NCI-GLOSS</n0:def-source></n0:ComplexDefinition>
<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A second or later vaccine dose, separated from the first by time, to increase, extend, or maintain the immune response of the previous vaccination.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>