The Green Book has the latest information on vaccines and vaccination procedures, for vaccine preventable infectious diseases in the UK.
https://www.gov.uk/drug-device-alerts/medical-device-alert-all-cochlear-implants-update-on-immunisation-recommendations
 

https://www.gov.uk/government/collections/immunisation-against-infectious-disease-the-green-book#the-green-book

Nasal flu vaccine in children with cochlear implants
The advice from the National Immunisation team (October 2021) is:
Children with cochlear implants can be vaccinated safely with LAIV (Live attenuated influenza vaccine) although ideally not in the week prior to implant surgery or for two weeks afterwards, or if there is evidence of on-going cerebrospinal fluid leak.
The nasal (nose spray) flu vaccine given to children is the LAIV.
 
This will be added to the Influenza Green book chapter very soon. Please talk to your GP if you have any questions.
 

Adults with cochlear implants and the flu vaccine
It is safe to vaccinate adults who have cochlear implants against influenza using the relevant licensed flu vaccines.

The relevant licensed vaccines for adults are not live. In special circumstances the nasal LAIV can be used for adults – for example as a reasonable adjustment in an adult with a learning disability (rather than administering an injection). Due to the vaccine being live, the same considerations that the team advised for children would be applied in this situation.