Travellers to Vietnam need to arrange comprehensive travel insurance before visiting the country, because there is no reciprocal healthcare agreement in place between the UK and the country.
Travellers are advised to carry a kit of basic medical supplies such as needles as there are shortages of such items throughout Vietnam.
Even in the major cities, hospitals in Vietnam are of a poor standard, and in rural areas, you should not trust them to administer an aspirin with anything approaching competence. Almost any condition you may acquire will require medical extraction back to the UK or to Thailand (costing around $15,000 and $100,00 respectively.) Make sure that you insurance covers this eventuality.
Malaria and Dengue Fever are a problem throughout the country, and you should consult a doctor prior to travel in order to arrange appropriate protection.