The intradermal vaccination of a live PRRS vaccine (UNISTRAIN® PRRS), through the new needle-free injector Hipradermic®, is safe when administered in swine according to the recommended vaccination program.
Current knowledge on PRRS virus immunology is still limited but it seems clear that modified live PRRS vaccines (MLV) are a reasonable choice for the immunization of pigs. Recently, interest in intradermal vaccination in swine has increased due to research into skin and subcutaneous tissue immunology and the possibility of using needle-free injection devices (NFIDs). The use of NFIDs in the swine industry offers some advantages over conventional needle-and-syringe methods, especially due to the reduced pain and stress to pigs and the increase in the uniformity of the dosage administered to the herd.
The MLV vaccine UNISTRAIN® PRRS has recently obtained the indication for intradermal administration with Hipradermic®, a needle-free injector with connectivity developed by HIPRA for the intradermal vaccination of pigs. A multicentre field trial was conducted under field conditions in order to demonstrate the safety of the intradermal administration of UNISTRAIN® PRRS in swine with Hipradermic® .
A multicentre, randomized, double-blind, controlled trial was carried out in 1532 animals (piglets from 3-4 weeks of age) distributed over 3 commercial farms (farms 1, 2 and 3) in Spain. The animals on each farm were randomly divided into two treatment groups. Group A (n=693) was vaccinated once at 3-4 weeks of age (day 0; d0) with 0.2 ml of UNISTRAIN® PRRS vaccine (103.5 CCID50/animal; strain) administered intradermally with Hipradermic®. Group B, (n=839) as a control group, was injected with 0.2 ml of PBS (phosphate buffered saline) also ID with the same device. All animals included in the trial were individually identified. The pooled results of the three farms were obtained.
Schedule of tasks performed:
These parameters were recorded for all the animals included in group A and compared with group B, to assess the safety of the UNISTRAIN® PRRS vaccine administrated intradermally.
No serious or unexpected adverse events attributable to intradermal vaccination with UNISTRAIN® PRRS were observed. Likewise, no post-vaccination general clinical signs attributable to vaccination with UNISTRAIN® PRRS vaccine were observed. No significant differences were observed between the groups in the increase in body temperature after vaccination.
Increase in rectal temperature after vaccination (ºC):
Regarding local reactions observed after vaccination, slight to moderate inflammation could be seen in group A, which resolved within 2 days post-vaccination. Redness was also observed at the inflammation area in some animals. No nodules were observed in any of the animals on any of the monitoring days. In all cases, reactions resolved spontaneously three days post-vaccination without treatment.
Local reactions observed after vaccination:
The results obtained allow us to conclude that vaccination with UNISTRAIN® PRRS vaccine is safe when administered to piglets by the intradermal route with Hipradermic® according to the recommended vaccination program.