The Wellcome Trust and other UK medical-research charities support the plans of the National Health Service (NHS) in England to make better use of information from patients' records, but we have no wish to downplay the right of people to opt out of the NHS care.data programme (go.nature.com/srp5nu), as you imply (Nature 505, 261; 2014). Like you, we believe it is critical that the risks, benefits and choices are explained clearly to everyone.

We have launched a campaign to support the wider use of medical records for research through mechanisms such as the Clinical Practice Research Datalink, rather than the care.data programme specifically (see www.patientrecords.org.uk). It is intended to complement NHS England's communications by highlighting the choices people have alongside the research benefits we perceive, and to help people to reach an informed decision.

Those with concerns about sharing patient data are right in that no system can guarantee protection against determined misuse. We have confidence, however, in the strict safeguards that govern the research use of medical records, which can manage those risks while enabling research to benefit from a national cradle-to-grave data set.