The prevalence of Bovine Viral Diarrhea (BVD) has remained constant over time, despite ongoing vaccinations to control the virus. What has changed is prevalence of the BVD strains responsible for infection. Strain 1a, which used to be the most prevalent found in BVD infections, has declined steadily for two decades. During the same period of time, the prevalence of BVD infections with strain 1b has increased 50%, according to Brad Williams, DVM, MBA at Elanco Animal Health. Until the recent introduction of Viralign 6 from Elanco Animal Health, no commercially available modified live vaccine for BVD contained strain 1b.