Presence of Virulent Newcastle Disease Virus in Vaccinated Chickens in Farms in Pakistan

One year after a virulent Newcastle disease virus (vNDV) outbreak in Pakistan, the causative strain was present in vaccinated chickens of multiple farms despite the existence of high-average NDV-specific antibody titers (>4.75 log(2)). The data suggest a possible role of vaccinated birds as reservoirs of vNDV.