作者单位:Univ Genoa, IRCCS AOU San Martino IST, Infect Dis Unit, Genoa, Italy[1]Univ Genoa, Dept Hlth Sci, Sect Biostat, Genoa, Italy[2]IRCCS AOU San Martino IST, Hygiene Unit, Genoa, Italy[3]Univ Genoa, IRCCS AOU San Martino IST, Dept Obstet & Gynecol, Genoa, Italy[4]