[1] Ctr Dis Control & Prevent, Natl Immunizat Program, Div Field Epidemiol, Program Epidemiol, Atlanta, GA 30333 USA
[2] S Carolina Dept Hlth & Environm Control, Columbia, SC 29201 USA
[3] Ctr Dis Control & Prevent, Div Viral & Rickettsial Dis, Natl Ctr Infect Dis, Atlanta, GA USA
[4] Greenville Hosp, Greenville, NC USA