use strict;
my $str = 'Read more: Indonesia to Get Moderna Vaccines Before the pandemic began, a lot of people were....';
my $regex = qr/^(?:Read\s+more\s*:)?\s*(?:(?:[A-Z]\S*|the|an?|[io]n|at|with(?:out)?|from|for|and|but|n?or|yet|[st]o|around|by|after|along|from|of)\s+)*(?=[A-Z])/mp;
my $subst = '';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html