Speaking in Kirklees, West Yorkshire, on Friday, the Prime Minister said: “I have complete confidence in Matt and indeed all of the Government who have been dealing with Covid-19 during the pandemic.”
In another message about struggles to procure ventilators, Mr Johnson responded: “It’s Hancock. He has been hopeless.”
No 10 did not dispute the authenticity of the messages from the early stages of the coronavirus pandemic but insisted Mr Johnson has full confidence in his Health Secretary.
Asked about the matter on Friday, Mr Johnson praised the “huge progress” being made by the NHS on the vaccine rollout, “with Matt at the top of it”.
“When you look at the vaccine rollout by the NHS, it is absolutely outstanding and I would just remind you that today under the leadership of Matt and the NHS we’ve now done I think 80% of adults...have now had their first jab, and we’re now asking 18 year olds to come forward.
“We’re making huge, huge progress and that’s down to the work of the NHS and with Matt at the top of it.”
On Thursday Commons Leader Jacob Rees-Mogg also defended Mr Hancock following criticism by his Labour counterpart Thangam Debbonaire.
Mr Rees-Mogg told MPs: “As regards text messages, there’s a great line from Dr Johnson that in lapidary inscriptions a man is not on oath and I think the same applies to text messages which are essentially the trivia, the flotsam and jetsam, the ephemera of life and fundamentally unimportant.
“The fact the honourable lady finds them so exciting shows how little she has to go on.”
Mr Rees-Mogg later described Mr Hancock as the “brilliant, one and only, successful genius” who has been running the Health Department.
Downing Street has declined to refute most of the allegations made on Wednesday in the blog post by Mr Cummings, who left Downing Street in November during a power struggle.