This randomized clinical trial evaluated the effect of upon-arrival intranasal vaccination against bovine coronavirus (BCoV) on pneumonia risk in a beef-on-dairy veal production system. Secondary objectives were to assess the effect vaccination on lung ultrasonographic cure, clinical bovine respiratory disease (BRD), average daily gain (ADG) and cold carcass weight (CCW). Belgian blue beef x Holstein calves (n = 217; age 14-21days) from multiple dairy farms were fattened in a single veal calf facility. On arrival, Immunoglobulin G (IgG) and serostatus for major respiratory pathogens were determined, and calves were randomized by weight and lung consolidation (LC) ≥ 1cm status into a vaccinated (IN) and placebo control group (NC). The study was triple blind with no other vaccines administered. Clinical scoring and quick thoracic ultrasonography (qTUS and qTUS score) were performed on arrival (T1), d 12 (T2), 22 (T3) and 70 (T4). Average daily gain (ADG) was calculated from arrival to d 70. CCW was collected in the abattoir. Bacterial culture and nanosequencing were performed on non-endoscopic broncho-alveolar lavage (nBAL) samples from 15 NC calves. Logistic regression and linear mixed models assessed vaccination effects on risk for LC, ultrasonographic cure (both as LC regression < 1cm or full reaeration), clinical BRD, ADG and CCW. On arrival, 13.4% (29/217) of the calves had IgG <7.5 g/L, 95.4% (207/217) were seropositive for BCoV, 1.4% (3/217) had clinical BRD and 8.8% (19/217) had LC ≥ 1 cm. By treatment initiation (T2), clinical BRD remained low (2.8% (6/217), while 42.9% (93/217) had LC ≥ 1 cm. Circulation of BCoV was confirmed throughout the study in 5/15 sampled NC calves. No differences in LC or clinical BRD were found between vaccinated calves and controls at any time point. Total cure was 45.2% (42/93) at short-term (T3) and 74.2% (66/89) at long-term (T4) evaluation and was not affected by vaccination group. Short-term cure immediately after treatment was significantly lower in calves with severe pneumonia (LC ≥ 3cm) as compared with mild (LC < 1cm) (odds ratio (OR) = 0.13; 95% confidence interval (CI): 0.04-0.39) or moderate pneumonia (LC ≥ 1cm) (OR = 0.33; 95%CI: 0.14-0.78). LC ≥ 1cm at arrival was positively associated with LC ≥ 1 at all subsequent observation points (P < 0.001). Calves with IgG <7.5 g/L upon arrival had higher odds for LC ≥ 1cm at T2 (P = 0.03) and T3 (P = 0.02). Vaccination was associated with a significantly higher mean ADG during the first 10 weeks (+0.041 kg/day, 95%CI: 0.004 -0.078) and a higher week-10 live weight (+3.0kg, 95%CI:0.27-5.74). Both week-10 ADG and severe pneumonia at T4 were associated with lower CCW. Upon-arrival vaccination did not reduce the risk of LC or improve the ultrasonographic cure under the conditions of this study. However, vaccinated calves showed a higher ADG during the first 10 weeks of production, which did not translate into differences in CCW. The lack of detectable effects on LC and cure may be explained by the high serostatus for BCoV, the low prevalence of failure of transfer of passive immunity, and the relatively high arrival body weights in the studied population.
Jourquin et al. (Mon,) studied this question.