Bovine respiratory syncytial virus (BRSV) is the leading cause of respiratory disease in young calves. The virus can also infect sheep and goats (Pirbright, 2023). In outbreaks, the infection rate is high, while the disease burden varies from asymptomatic to fatality rates approaching 20% (Pirbright, 2023). BRSV is associated with considerable economic losses due to the associated morbidity, mortality, costs of treatment and prevention, fall in milk yield and reduced carcass value (Giammarioli et al, 2020). The use of existing vaccines in young calves is complicated by maternally-derived antibodies (MDA) compromising efficacy in very early life (Martinez et al, 2022). The short duration of immunity and risk of shedding of attenuated vaccine strains are also seen as limitations of current commercial vaccines (Meyer et al, 2023).
In the UK, the at-risk population is better understood as two major windows of vulnerability: an early-life cohort in which maternally derived antibodies may interfere with conventional vaccination, and a post-weaning cohort in which stress, transport, and commingling can increase disease risk.
UK at-risk calf populations*
Dairy-origin: 1.57 million calves/year
Beef-origin: 1.1 million calves/year
Costs the UK cattle industry: £54 million calves/year (Pirbright, 2023)
US context*
Dairy-origin: 8.2 million calves/year
Beef-origin: 18.7 million calves/year
*based on government sources.
Pirbright - BRSV