Modeling Economic Effects of Vaccination Against Porcine Reproductive and Respiratory Syndrome: Impact of Vaccination Effectiveness, Vaccine Price, and Vaccination Coverage

Abstract

Porcine reproductive and respiratory syndrome (PRRS) causes substantial financial losses in pig farms and economic losses to societies worldwide. Vaccination against PRRS virus (PRRSV) is a common intervention in affected farms. The aim of this study was to assess the economic impact and profitability of potential new PRRS vaccines with improved efficacy at animal, herd, and national level. Two vaccination strategies were modeled; (i) mass vaccination of sows only (MS) and (ii) mass vaccination of sows and vaccination of piglets (MSP), comprising different scenarios of vaccine effectiveness, vaccine price, and vaccination coverage. A farrow-to-finish farm with 1,000 working sows from a pig-dense region in Germany served as an example farm. Financial benefits were obtained from gross margin analyses and were defined as difference in gross margin between a PRRSV-infected farm without vaccination (baseline) and with vaccination (intervention). Financial benefits were highest if both sows and piglets (MSP) were vaccinated. In these scenarios, median annual net benefits per working sow ranged from e170 to 340. If sows only were vaccinated (MS), estimated benefits attributable to vaccination were between e148 and 270. Decisive variables for the estimation of national level benefits were the number of farmers switching from existing to a better protecting vaccine, the number of previously non-vaccinating herds adopting the new vaccine, and the effectiveness of the new vaccine relative to those already available. Benefits were greatest when the new vaccine was adopted by previously non-vaccinating herds. The analyses showed that vaccination against PRRS was beneficial for all modeled scenarios. The magnitude of benefits derived from vaccination was more susceptible to changes in vaccination effectiveness than to vaccine price changes. This study provides evidence to support future vaccine development. The estimates indicate that the introduction of more efficient vaccines might lead to substantial financial benefits, is of socioeconomic importance and that new vaccines might significantly contribute to the reduction of disease burden.

Modeling the transmission and vaccination strategy for porcine reproductive and respiratory syndrome virus

“…On the other hand, the prophylactic #2 strategy would be independent from diagnostics costs, and thus implementation could be considered more feasible by the swine industry. Before recommendations can be made, future longitudinal studies need to evaluate the economics of each vaccination strategy taking into consideration the cost to stabilize an infected farm (Linhares et al, 2015; Nathues et al, 2017; Thomann et al, 2020). Until diagnostic techniques become more accessible and easier to perform, the effectiveness of strategies involving the identification of PRRSV in downstream pig operations remains questionable.…”

Using PRRSV-Resilient Sows Improve Performance in Endemic Infected Farms with Recurrent Outbreaks

“…It was not considered that piglets from resilient sows will probably also develop better throughout the growing period. For this reason, the GM calculated here is likely underestimated with respect to the values obtained in cases where the impact of PRRSV is measured until the end of the growing phase [ 13 ].…”

“…This finding is in agreement with the experiment described by Abella et al (2019) [ 11 ], where the largest difference between resilient and susceptible sows was observed for mummified piglets during a PRRSV outbreak, and with the fact that increased mummified piglets is the most identifiable clinical outcome in an acute PRRSV outbreak in sows. Note, however, that the variable we used for measuring the losses of the gestation rate is not comparable with the abortion rate, commonly used in many studies addressing a PRRSV economic analysis [ 12 , 13 ]. The abortion rate only accounts for losses in the fetal stage (≥35–40 days of gestation), whereas the losses of gestation rate includes both embryonic and fetal losses.…”

“…We found that the piglet production cost is 3% lower in a PRRSV endemic than in a PRRSV endemic/epidemic scenario, which is in line with the results from theoretical studies on the cost and impact of associated control measures against PRRSV [ 12 ]. Interestingly, in a PRRSV endemic/epidemic scenario, the piglet production cost is significantly lower for resilient (1%) sows as compared to susceptible sows, which confirms breeding for resilience as an interesting strategy for PRRSV control [ 13 ]. Moreover, as a proactive prevention measure, compared to reactive disease treatments, resilience is widely accepted amongst consumers [ 37 ].…”

“…This information is very difficult to be obtained experimentally due to the necessity to have a complete farm with PRRSV resilient or susceptible sows. In the literature, modeling has been used to predict the effects of future interventions for PRRSV control and its economic impact [ 12 , 13 ].…”