Nobivac^® Myxo-RHD PLUS Questions and Answers

Nobivac Myxo-RHD PLUS is MSD Animal Health’s new vectored vaccine, which provides 3 in 1 coverage against myxomatosis, classic and variant strains of Rabbit Haemorrhagic Disease (RHD), ensuring rabbits are immunised against both common strains of RHD.

An emerging variant strain of Rabbit Haemorrhagic Disease (RHD-2) was discovered in 2010 in France and has since become widespread in the UK. Further research and pharmacovigilance demonstrated that demonstrate that vaccination with classic (RHD-1) strains does not provide reliable immunity against the variant RHD-2 strains.

Nobivac Myxo-RHD PLUS now includes two RHD-vectored myxoma strains to provide comprehensive immunity against myxomatosis, and both classic and variant RHD.

Nobivac Myxo-RHD PLUS provides broad cover against myxoma virus and both RHD-1 and RHD-2 from a single vaccine using the same recombinant vector technology present in Nobivac Myxo-RHD. The vaccine contains a similar amount of classic strain vector to Nobivac Myxo-RHD, ensuring no reduction of antigenicity against this component.

A convenient single dose given from 7 weeks of age provides protection against all 3 pathogens with a minimum duration of immunity of 12 months.

The new vaccine has a number of advantages/benefits:

1.      Vaccinates against both field strains of RHD

- contains equal quantities of both myxoma-virus vectored classic RHD-1 and variant RHD-2 strains. Both strains use VP 60 capsid genes.

2.      No adjuvant is required as it is a live vectored vaccine

3.      Lower volume to administer compared to Nobivac Myxo-RHD

- reconstituted with 0.5 ml of vaccine solvent rather than 1 ml

4.      May be given from 5 weeks of age 

- however, to avoid a reduction duration of immunity caused by MDA in some rabbits, vaccination after 7 weeks of age is recommended

5.      Approved for use during pregnancy

Nobivac Myxo-RHD PLUS has proven efficacy in naïve rabbits and effectively boosts rabbits previously vaccinated against myxomatosis, RHDV-1 and RHDV-2. However please note that Nobivac Myxo-RHD PLUS vaccine product labelling also includes the following statement:

Rabbits that have been vaccinated previously with another myxomatosis vaccine, or that have experienced natural myxomatosis infection in the field, may not develop an adequate immune response against rabbit haemorrhagic disease following vaccination.

This statement relates to the phenomenon of vector interference which is very relevant to a very specific subset of rabbits being switched over to the new vaccine. Based on the results of efficacy and switching studies, an optimum approach to avoid this potential risk as laid out below. 

Annual boosters for all groups of rabbits in all subsequent years can be managed successfully with Nobivac Myxo-RHD PLUS.

No more Nobivac Myxo-RHD is being manufactured and stocks will run down during the year. We recommend that while stocks last that the legacy vaccine is reserved to dose rabbits that need to be given an inactivated RHDV-2 vaccine this year (please see switching advice above).