About one million people opted out pre-emptively, although the NHS was recently forced to admit it has not yet processed their objections.
Despite being the 'senior responsible owner' (civil service jargon for the most senior person in charge) of the Care.data scheme, Kelsey has managed to avoid much real criticism for the project's problems.
When blamed, he has generally reacted with surprise and irritation, both in appearances in front of select committees and his activity on Twitter, which has decreased greatly since the project started to go awry.
There was a minor media flurry after Kelsey featured in a mocked-up 'Downfall' video on YouTube, which parodied Kelsey as Hitler during his last days in the bunker: an angry, delusional figure unable to understand why his plans had gone wrong.
It was retweeted by his then-boss NHS chief David Nicholson, who was pressured into apologising, tweeting 'You're doing a great job X' to Kelsey shortly afterwards.
Despite all the problems with Care.data, Kelsey has weathered the storm so far. He therefore presumably must still have the trust of his boss, Health Secretary Jeremy Hunt, and indeed the man who first brought him into the inner circles at the top of government: David Cameron.
Kelsey is admired by many for his role in helping to kick-start the opening up of public sector data and his grand vision for how information and technology could radically improve NHS care.
As architect of the NHS Choices website, which provides advice and information on conditions, treatments and local NHS services, Kelsey has helped to improve transparency on individual hospitals' mortality rates, reviews by patients and other data on outcomes.
He has a reputation as an intelligent, powerful and effective operator.
However, in public appearances he can come across as dogmatic and bad at taking criticism. He also seems to have benefitted from favouritism and naivety in Whitehall.
Kelsey was certainly helped by the latter in the case of Dr Foster, when a 50 percent stake in the firm - of which he owned 12 percent - was sold to the Department of Health in 2006 for £12 million, double its estimated value.
It was since bought by Australian telecoms giant Telstra in March 2015 for 'between £10 million and £20 million' - in total.
The Public Accounts Committee and National Audit Office raised serious concerns about the legality of the health department contract, describing it as a "back room deal" which had been "handed to Dr Foster on a plate".
The NAO concluded the department had not gone through proper procedures and could not show value for money from the purchase.
Denise Lievesley, the whistleblower who first raised concerns about the contract, was eased out of her job as chief executive of the NHS Information Centre and forced to sign a gagging clause. To this day she remains unable to tell her side of the story.
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