What it does
VAPOR is a tool for classification of Influenza samples from raw short read sequence data for downstream bioinformatics analysis. VAPOR works on a fasta file of full-length reference sequences for a given genome segment and a set of sequenced reads, and attempts to retrieve the reference that is closest to the sequenced strain.
sub_sample is not an option here (compared to the tool on GitHub), since you can always build a workflow that preprocesses your reads to a (random) subsample. You can use this output as your reads file for VAPOR.