Subject searches to use in SOLO:
Right to health --
Noncitizens -- Medical care --
Health services accessibility -- Law and legislation
Noncitizens -- Medical care -- Law and legislation
Emigration and immigration -- Health aspects
Health services accessibility
Immigrants -- Medical care
Medical policy
Irregular Migrants and the Right to Health by 
Advancing the Human Right to Health by 
Foundations of Global Health and Human Rights by 
The Health of Newcomers : Immigration, Health Policy, and the Case for Global Solidarity by 
Patients with Passports: Medical Tourism, Law, and Ethics by Two phrases which you might encounter are health tourism and medical tourism. Sometimes these are used interchangably, sometimes the author or commentator has a precise distinction in mind.
Health tourism can sometimes be limited to choice of destination for improved well-being eg selecting a hotel because of the facilities or services it provides.
Medical tourism can sometimes be specifically limited to those who go to another country to make use of medical/dental facilities and practitioners or because a drug or treatment is not authorised in their home country, or there is too great a delay.
Both categories are tourists because they intend to return home after.