Footnotes

• Handling editor Anna Maria Geretti

• Contributors RKJT, VH and MLW conceptualised and designed the study. RKJT, JML, JJML, AKJT and MLW conducted the interviews and analysed the data. RKJT wrote the first draft of the paper. All authors contributed to final revisions to the text and read and approved the final manuscript.

• Funding This study was funded by the Saw Swee Hock School of Public Health, National University of Singapore.

• Disclaimer The authors" work was independent of the funders, who had no role in the design, collection, analysis or interpretation of the data or the decision to submit for publication.

• Competing interests None declared.

• Patient consent for publication Not required.

• Ethics approval Ethics approval was granted by the Saw Swee Hock School of Public Health Department Ethics Review Committee (Reference: SSHSPH-028).

• Provenance and peer review Not commissioned; internally peer reviewed.