Table 2.

Reasons for non-enrolment of cases.

Case	BT20 contact points	Reason for non-enrolment
Contact established with four cases
A	Immunization	No time for interview at first point of contact. BT20 staff did not follow up.
B	Hospital	Declined participation due to pending migration out of study area.
C	Birth site	Clinic provided incorrect contact details.
D	Immunization	Declined participation due to privacy concerns.
Contact not established with six cases
E	BT20 site for birth only	Planned to leave the study area after birth. Not recruited into the study. Subsequently, frequent migration for employment reasons. Failure to recruit during follow-up stages.
F	BT20 site for birth and present in study area after birth	BT20 staff failed to recruit at time of birth. Subsequently, frequent migration for employment reasons. Failure to recruit during follow-up stages.
G	BT20 site at four data collection points	Alternative English name used at birth and family moved to the outskirts of study area. Failure to contact at follow-up stages.
H	BT20 site at four data collection points	BT20 staff failed to recruit at time of birth. Family moved to the outskirts of study area. Failure to contact at follow-up stages.
I	–	White family used private facility for birth hence no contact with BT20 staff.
J	–	White family used facility outside the study area for birth hence no contact with BT20 staff.