About the Authors

Robert Cockburn

Contributed equally to this work with: Robert Cockburn, Paul N Newton

To whom correspondence should be addressed. E-mail: rcockburn@libero.it

Paul N Newton

Contributed equally to this work with: Robert Cockburn, Paul N Newton

E. Kyeremateng Agyarko
Dora Akunyili
Nicholas J White

Competing Interests

NJW is on the editorial board of PLoS Medicine. RC, PNN, EKA, and DA declare that they have no competing interests.

Author Contributions

All authors researched the information for this review, RC and PNN wrote the first draft, and all authors contributed to writing the final version of the manuscript.