Study design and participants
Nasopharyngeal flocked swab (FLOQSwabsTM, Copan Diagnostics, Murrieta, CA, USA) samples and serum were collected from children enrolled in a single-centre, open-labelled, randomised trial to evaluate the non-inferiority of a 1 + 1 compared with a 2 + 1 dosing schedule of PCV10 and PCV13 in Soweto, South Africa.The study was approved by the Human Research Ethics Committee, University of Witwatersrand, Johannesburg, South Africa, and the South African Health Products Regulatory Authority. Written informed consent was obtained from the parents or guardians of all participants at the time of initial enrolment. The 