Initial sterility study of a rabbit hemorrhagic recombinant subunit vaccine when used in a multidose manner across 16 days

Background

The introduction of a domestically produced Rabbit Hemorrhagic Disease type 2 (RHDV2) Vaccine (Medgene Labs) has been a welcome relief to veterinarians, rabbitries, and pet rabbit caretakers. Currently, the vaccine is only available in a 10-dose vial that must be used immediately. The purpose of this study was to determine if the vaccine can maintain sterility as a multidose vial across 16 days.

Methods

Over a period of 16 days, a total of ten 0.5 mL samples were aseptically collected from 2 experimental vaccine bottles, and 1 control bottle was sampled on day 10. A total of 21 aerobic bacterial cultures and 5 fungal cultures were collected. The samples were collected daily, that all vials were opened on the first day of the experiment and the control vial was pierced for the first time on day 10.

Results

Of the 21 aerobic bacterial cultures collected and 5 fungal cultures collected over 16 days, there was no growth detected by the microbiology lab.

Conclusion and clinical relevance

In summary, this study provided evidence that when collected with appropriate aseptic precautions, the recombinant subunit RHDV2 vaccine could potentially be used extra-label, once fully approved by the USDA, as a multidose vial for at least 16 calendar days without compromising sterility, pending pyrogen and endotoxin testing as well as anaerobic cultures and potentially next generation DNA sequencing.