[1] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Int Hlth, Ctr Immunizat Res, Baltimore, MD 21205 USA
[2] Johns Hopkins Bloomberg Sch Publ Hlth, Int Vaccine Access Ctr, Baltimore, MD 21205 USA
[3] Johns Hopkins Sch Med, Dept Pediat, Div Infect Dis, Baltimore, MD USA
[4] Canterbury Hlth Labs, Microbiol Unit, Christchurch, New Zealand
[5] Univ Otago, Dept Pathol, Christchurch, New Zealand