Health CS Sicily Kariuki has explained why four counties were chosen for the Universal Health Care pilot.
They are; Kisumu, Nyeri, Machakos and Isiolo.
Kariuki said Kisumu was chosen because it has the highest disease burden of communicable ailments such as malaria, TB, HIV and Aids.
There is a high number of new HIV infections among teenagers in the country and particularly in Nyanza, Western, Nairobi and Coast regions.
The majority of new infections are reported among teenagers and youth between 16 and 25 years.
A National Aids Control Council report put the number of new infections among adolescents and young persons in Kenya at 47 every day.
Machakos was chosen because it has the highest incidents of trauma cases due to its proximity to accidents happening on the Nairobi-Mombasa highway.
The county has registered many accidents, with the latest incident being on Monday where five people died at Kapiti plains when the matatu they were travelling in collided with a lorry.
Nyeri was chosen because it has the highest disease burden of non-communicable ailments, particularly diabetes.
Kariuki said Isiolo has a unique nature of pastoralists who move often, changing their medical facilities and interrupting their medication.
Isiolo was found to be among the 15 counties with high maternal mortality rates and represented a sparse population.
At least 3.2 million Kenyans will be the first beneficiaries of the health package during the pilot.
Kenya is expected to inch closer to its goal of attaining Universal Health Coverage by 2022 when President Uhuru Kenyatta launches the pilot phase of the programme on Thursday in Kisumu.
WHO defines universal health care as ensuring all people have access to quality preventive, promotive, curative, rehabilitation and palliative health services regardless of their ability to pay.
During the piloting phase, the UHC package will cater for outpatient care such as consultation, mental illness and emergency health care.
Inpatient care will include medical and surgical services, enhanced maternal and child health services and enhanced HIV, tuberculosis and malaria treatment.