The European Health Insurance Card (EHIC) which replaced the E111 in 2006 can be used to cover any necessary medical treatment due to either an accident or illness while on holiday in Tenerife (or elsewhere within the European Economic Area and Switzerland).
Not all services you would expect within the UK will be covered and you may have to make a contribution towards the care you receive.
There is no information on the EHIC website specific to its use for the treatment of swine flu but it might be the only cover you have unless you have read the fine print of your travel insurer or called them to confirm that they do offer pandemic cover.
The EHIC can only cover you if you show it upon arrival at the hospital. To be on the safe side, carry it with you at all times.
[...] Continued here: Holidaymakers – Carry Your EHIC At All Times [...]