aDivision of Infectious Diseases, Beth Israel Deaconess, Medical Center, Boston, MA, USA
bHarvard School of Public Health, Department of Biostatistics, Boston, MA, USA
cDepartments of Medicine and Pediatrics, Massachusetts, General Hospital, Boston, MA, USA
dDepartment of Medicine, Brigham and Women's Hospital, Boston, MA, USA
eDepartment of Medicine, University of Pittsburgh,Pittsburgh, PA, USA.
Correspondence to Roger L. Shapiro, MD, MPH, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA. Tel: +1 617 771 0040; fax: +1 617 632 0766; e-mail: firstname.lastname@example.org
Received 27 September, 2011
Accepted 28 September, 2011