[1] UNIV GOTHENBURG, INST MED MICROBIOL, DEPT VIROL, GOTHENBURG, SWEDEN
[2] UNIV GOTHENBURG, DEPT INFECT DIS, GOTHENBURG, SWEDEN
[3] UNIV GOTHENBURG, DEPT OBSTET & GYNECOL, GOTHENBURG, SWEDEN
[4] UNIV GOTHENBURG, DEPT PEDIAT, GOTHENBURG, SWEDEN
[5] EASTERN HOSP, DEPT OBSTET & GYNECOL, GOTHENBURG, SWEDEN