Corrigendum
Bulletin of the World Health Organization 2011;89:863-863. doi: 10.2471/BLT.11.101211
In Volume 89, Number 11, November 2011, p. 808, the 3rd and 5th equations should read:
Bulletin of the World Health Organization 2011;89:863-863. doi: 10.2471/BLT.11.101211
In Volume 89, Number 11, November 2011, p. 808, the 3rd and 5th equations should read: