Kamau will be at the helm of the national health insurer for three years, effective December 23, 2022.
"In exercise of the powers conferred by section 4(1)(a) of the National Health Insurance Fund Act, I, William Samoei Ruto, President and Commander-in-Chief of the Defence Forces of the Republic of Kenya, appoint Michael Kamau (Eng.) to be the Chairperson of the National Health Insurance Fund, for a period of three years, with effect from the 23rd December 2022," the notice reads.
Before the revocation of his apportionment, Nguyai, who was appointed in February, was supposed to serve until 2024.
NHIF is among parastatals that Ruto has earmaked for reforms and increased funding as part of his plan to fully implement the universal health coverage for all Kenyans.
Ruto has indicated that he would want big earners to pay more to NHIF as opposed to the current arrangement where a maximum paymemt is Sh1,700.
Also affected in the changes is former Chief of Defence Forces Gen (Dr) Julius Karangi who has been moved from the National Social Security Fund (NSSF) Board of Trustees to the less glamorous National Council for Population and Development Board.
Karangi, who served as CDF during Uhuru's tenure, replaces David Ngugi as chair of the board until July 20, 2024.
The general's current position at NSSF Board will be held by Antony Muriuki Munyiri, who will serve for three years.
The Head of State has also appointed Lt Gen (Rtd) Walter Rarira Koipation as the chairperson of the Kenya Wildlife Service (KWS) Board for three years.
Koipaton replaces Gen (Rtd) Joseph Kibwana.
The president has also appointed Faith Boinett to chair the Kenya Pipeline Company Limited (KPC) Board of Directors for three years.
"The appointment of Rita Achieng Okuthe is revoked," Ruto said.
In the last three months , Ruto has been picking his allies and loyalists to replace Uhuru's close confidants.
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Nguyai was former president Kenyatta's witness during the pretrial conference at the International Criminal Court (ICC) at The Hague and has been a close confidant of the former head of state.
Last month, Ruto picked his United Democratic Alliance (UDA) National Election Board Chair Antony Mwaura to chair the Kenya Revenue Authority (KRA) Board for three years.
After the appointment, the president gave Mwaura a target of collecting Sh3 trillion in the 2022/23 financial year and Sh5 trillion in the next three years.
Another of Ruto's allies who has been rewarded after falling out with Uhuru was former Kiambu Governor Ferdinand Waititu who was picked to chair the Nairobi River Regenation Programme.