FOI2026/00784 - Lack of efficacy regarding Nobivac RHD Plus
Published 13 July 2026
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1. Your request
Please could you send me a summary of any lack of efficacy concerns regarding Nobivac RHD+ in relation to protection against CHD viruses?
2. Our reply
Nobivac Myxo-RHD PLUS lyophilisate and solvent for suspension for injection for rabbits is a veterinary medicinal product (VMP) used for active immunisation of rabbits from 5 weeks of age onwards to reduce mortality and clinical signs of myxomatosis and rabbit haemorrhagic disease (RHD) caused by classical RHD virus (RHDV1) and RHD type 2 virus (RHDV2).
As per our guidance (Guideline III Adverse event reporting - GOV.UK), we define lack of efficacy as “the apparent inability of an authorised VMP to have the expected efficacy in an animal, whether or not the product was used in accordance with the Summary of Product Characteristics (SPC).” The SPC is a document describing the properties and the officially approved conditions of use of a medicine. The SPC and associated product information are updated as new information is available, and the latest version of an SPC can be found on our publicly available Product Information Database.
The SPC for Nobivac Myxo-RHD contains the following warnings in section 4.4 regarding lack of efficacy:
‘Vaccinate healthy animals only. High levels of maternally derived antibodies against myxoma virus and/or RHD virus can potentially reduce the efficacy of the product. To ensure the full duration of immunity, vaccination from 7 weeks of age is advised in this case. 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.’
In our response we have included all adverse event reports. This includes reports involving the scenarios specified in section 4.4, reports where the lack of efficacy was not confirmed by testing, reports when the product was used off-label, that is using a medicine in a way that is not specified on the product’s label, reports where more than one product was used, or reports where, on further evaluation, there may have been other reasons for the adverse event occurring.
Please be aware that the data we have provided below are not subject to independent verification and the VMD does not guarantee their accuracy.
| Number of animals reported as exhibiting suspected lack of efficacy against RHD virus following administration of Nobivac Myxo-RHD PLUS |
|---|
| 140 |
The number of adverse events alone cannot be used to determine the likelihood of an event occurring. This is because the numbers need to be put into context considering other factors such as differing sales volumes.
Evaluation is dependent on the accuracy and quality of data received from veterinary professionals and animal owners, and reporting frequency can vary over time (reporting frequency may be affected by a product being new to the market or social media interest, for example).