False about antigen drift-
Causes pandemic
Occurs due to mutation
Occurs more frequently
Affected by previous antibodies
Antigenic shift (not drift) is responsible for pandemic.
Antigenic drift occurs due to point mutation.
Antigenic drift occurs more frequently (2-3 years) than antigenic shift (10-15 years).
Antigenic drift is influenced by the presence of antibodies to the predecessor strains in the host population.