[1] Harvard Univ, Sch Publ Hlth, Dept Social & Behav Sci, Ctr Global Tobacco Control, Boston, MA 02115 USA
[2] Univ Lagos, Coll Med, Dept Community Hlth & Primary Care, Idi Araba, Lagos State, Nigeria
[3] Johns Hopkins Bloomberg Sch Publ Hlth, Inst Global Tobacco Control, Baltimore, MD 21218 USA
[4] Univ Limpopo, Sch Oral Hlth Sci, Off Dean Director, Pretoria, South Africa