Yes, this treatment, which is also fairly new in France, is reimbursable here, at the usual 65%, or 100% in the case of someone with a recognised affection de longue durée (ALD), which would be the case if you suffer from certain serious arthritic conditions such as the first reader.
However, rheumatologist Charley Cohen from Paris said it is considered an exceptional treatment, to be used because other standard ones have not worked. To be prescribed it, you need to see a rheumatologist in a hospital. It costs around €600-€1,200 per monthly injection.
He said the treatment is a kind of biothérapie which stops the development of the illness. “It’s only used in severe cases, when we’ve tried other local injections or pills, and we need to act quickly.”
Most people who move to France initially use cover from an EHIC form, aimed at treatment that becomes necessary during a visit to the country, and then move fully into the French system once they have settled in. If you are a UK state pensioner, make sure you have an S1 form from the DWP, which guarantees your right to join the system in France and which you can use to register with a local state health insurance body (Cpam). Only early retirees need a private policy.
Brexit is creating uncertainty but if there is a deal, healthcare arrangements would be protected for pensioners coming before 2021.
If there is no deal, it would depend on what measures the UK and France and/or the EU take to remedy this but those established before Brexit day are expected to be prioritised in terms of protection of their rights, including healthcare.
Healthcare in France*
Inheritance Law and Wills in France* 
