Yes – you can continue to use your European Health Insurance Card (EHIC) or get a provisional replacement certificate (PRC) if you need treatment and do not have a card.
Your EHIC will still be valid in the EU until it expires. Once your EHIC has expired you will be able to replace it with a Global Health Insurance Card (GHIC).
With the new GHIC and your current EHIC, you will be entitled to healthcare in any of the 27 countries in the EU apart from Norway, Iceland, Liechtenstein or Switzerland.
Any specialised treatment, such as dialysis or cancer treatment, "must be subject to a prior agreement between the insured person and the unit providing the treatment," to ensure the treatment is available.
Even with EHIC and GHIC cover, it is still advisable that you buy travel insurance with healthcare cover before you go on holiday.
The new GHIC card is free from the official NHS website. You should apply at least 2 weeks before travel to make sure the card arrives on time. Beware of unofficial websites, which may charge if you apply through them.