Porcine circovirus type 2 (PCV2) genotyping in Austrian pigs in the years 2002 to 2017.

Extensive PCV2a-derived vaccination resulted in a reduction of prevalence and in a stabilization of genotype PCV2a, whereas genotypes PCV2b and PCV2d evolved as a consequence of natural and vaccination-induced selection. An ongoing virus circulation may be the result of reduced vaccine-induced protection.