A European Health Insurance Card (EHIC) gives you the right to access state-provided healthcare during a temporary stay in the EU. If you currently have an EHIC that is in date, this is still valid until the expiry date.
If your card has expired or you do not have one, this is now being replaced by a new UK Global Health Insurance Card (GHIC).
You can see more information and apply for a GHIC here.
The EHIC and/or GHIC do not replace travel insurance, this should also be purchased and work alongside the GHIC.