UK Malta reciprocal health agreement stays
 

'While the EU gave its citizens the right to free healthcare in all member states, Malta has a bilateral agreement with the UK, dating back to 1975, that allows for Maltese nationals to receive free healthcare in the UK. This agreement, which is renewed every year, should remain in place even after Britain leaves the EU'.

Brexit: Malta-UK free healthcare agreement to remain in place even after Britain exit from EU - The Malta Independent

Re: UK Malta reciprocal health agreement stays
 

Yes. That agreement long precludes the EU membership of Malta (and even the UK) and will stay in place whether the EU stays or goes.