The NHS and Europe - which is the healthier option?
Much of the debate about whether Britain stays in or leaves the European Union focuses on the flow of people. So it's not surprising that there has been discussion of how the NHS might be affected, both in terms of patient numbers and the supply of doctors and nurses.
The issue came up again in the BBC's Wembley debate on Tuesday evening.
The Leave campaign argues that the UK outside the European Union will be able to adopt its own border controls and limit the number of people arriving.
The question is what impact that might have on the health service's ability to recruit staff at a time of shortages, rota gaps, and rising agency bills.
There's no doubting the importance of overseas staff to the running of the NHS across the UK.
According to figures from the General Medical Council, collated by Nuffield Trust, there were 273,773 doctors registered in the UK in 2015. Of those, more than a third (99,898) had qualified in other countries, and about a third of which were in the European Economic Area.
Last year there were 693,996 nurses, midwives and health visitors registered to work here according to the Nursing & Midwifery Council. Of these, 98,217 qualified in other countries, about a third of which were in the EEA.
It's worth noting that those who qualified elsewhere include British doctors and nurses who chose to study abroad. It could include foreign health workers who after taking up jobs in this country then decided to take British nationality.
So what would happen if there was a Brexit?
Lord Crisp, a former head of the NHS in England, told me he was worried that it would be harder to recruit and hold on to those foreign staff.
"I think there must be a risk that if we leave the EU some of those people make a decision to go elsewhere or to leave the country. We just don't know what the position will be. We can't see any way whereby if we leave the EU we will get more so I think the risk is all one way."
Taking a very different view is Lord Owen, a doctor and former health minister. He says if the UK was outside the EU it could still admit foreign health staff under a visa system which recognised essential skills.
But even better, he argues, more medical staff should be trained closer to home:
"We could be virtually self-sufficient in nurses, the same for doctors - the management planning over the last 15 to 20 years has been deplorable, and that is the real weakness in the costings of the NHS".
So what about patients?
Simon Stevens, chief executive of NHS England, argues that the service has coped with an increasing population since it was founded in 1948 and there is no reason to think it won't continue to do so.
The Remain campaign argues that EU migrants tend to be younger and healthier, and research by University College London suggests they have contributed far more in taxes than they received in benefits and public service. Another study by the Civitas thinktank, however, suggests this "surplus" is not so clear cut.
Vote Leave predicts migration from the EU will mean a 4.25m increase in population by 2030. This in turn could see a 46% surge in demand for A&E services. The forecast assumes that five new countries, including Turkey, will join the EU in 2020 (which has been contested by the Remain campaign).
Ruth Thorlby, assistant director of policy at the Nuffield Trust, says it's hard to foresee what movements of population there might be and how that might affect the health service.
"I think it's difficult to predict patient demand at the best of times. If we leave the EU we simply don't know what will happen to the EU migrants who already live here. On the other hand we don't know what will happen to the British people in the EU - will they decide to come home?"
The economy and its impact on the NHS has featured heavily in the debate. According to Remain, if Brexit happens there will be a financial downturn which they say will mean cuts to public spending on areas like health.
Vote Leave says that is unjustified scaremongering. The Leave campaign claims that leaving the EU could allow the government to spend an extra £100m a week on the NHS by 2020. Remain has dismissed that figure accusing their rivals of writing cheques that they know will bounce.
Amidst all the sound and fury of the EU debate, there seems to be agreement on one thing - the future of the NHS under different scenarios, perhaps unexpectedly, became one of the central issues of the campaign.
Correction: The figure for the number of nurses, midwives and health visitors who registered to work in the UK has been corrected. It is 98,217, and not 99,898 as originally stated.