Junior doctors in England have announced plans to strike on five consecutive days later this month, the latest action in a long dispute over contracts.
The dispute centres on a row over a new contract that the government has said it will impose, and which it says is needed in order to meet its commitment to a seven-day NHS.
Junior doctors argue the contract is unsafe, and does not do enough to reward those who work the most weekends.
However Scotland, Wales and Northern Ireland are not affected. The BBC's health correspondents in the nations explain why.
You can read more on the dispute here.
Eleanor Bradford, BBC Scotland health correspondent
The Scottish government has decided not to introduce a new contract - for now.
It is keeping junior doctors on their old contract because it says there is not enough evidence yet of an increase in deaths at the weekends - and even if there are differences at the weekend, it doesn't believe junior doctors alone can solve that.
It says the whole system needs to change, including access to diagnostic tests and better social support to allow patients to be discharged.
While the row over the new contract rages in England, the Scottish government is hoping that some junior doctors based in England may be tempted to look north for their careers, which could help it address staff shortages.
Either way it's a win-win situation.
If the new contract in England does make a positive difference, Scotland can introduce it later. If it doesn't, the Scottish government has avoided all the controversy and may even benefit with a few more doctors staffing the rotas.
Owain Clarke, BBC Wales health correspondent
The Welsh government in Cardiff says, for now, it intends to stick with the junior doctors' contract already in force.
But that's not to say that hospital care at evenings and weekends isn't a concern here - with the public service ombudsman for Wales calling for an independent review - citing several examples of "inadequate care" - including where junior doctors haven't been properly supervised.
The Welsh government says improvements are already under way but it's looking at better weekend access to diagnostic tests, pharmacies and therapies instead of making major changes to work-patterns
Above all, ministers in Cardiff are keen avoid a dispute with frontline staff and say changes can only be made by working alongside health professionals.
But that's not to stay that if big changes eventually occur in England, the Welsh government won't have to consider the implications carefully.
It would arguably be difficult for the NHS on both sides of the border to work with different contracts for staff doing similar jobs.
Marie-Louise Connolly, BBC Northern Ireland health correspondent
In Northern Ireland, junior doctors haven't been taking part in strikes - and won't be striking later this month.
Stormont's new health minister Michelle O'Neill says she has no plans to impose a contract on junior doctors and any negotiations will be subject to engagement with the BMA.
Previous health minister Simon Hamilton described an imposed contract as "the worst possible outcome for everyone".
Junior doctors say they agree that imposing a solution would be devastating.