$ perl -Mstrict -Mwarnings -E 'my $author = q{Smith, Kristen A.}; $author =~ s/([^,;]+),([^,;]+)/$2 $1/g; say $author'
 Kristen A. Smith

##</code><code>##

$ perl -Mstrict -Mwarnings -E 'my $author = q{Smith, Kristen A.}; $author =~ s/([^,;]+),([^,;]+)/$2, $1/g; say $author'
 Kristen A., Smith