Confirmed cases decreased by 98.0% between 1998 and 2006, but there was an outbreak between 2006 and 2009, primarily affecting young men who had not been included in the vaccination campaign, which was aimed at women of childbearing age.
Los casos confirmados disminuyeron en 98,0% de 1998 a 2006, pero se presentó un brote entre 2006 y 2009 que afectó con mayor frecuencia a hombres jóvenes, no incluidos en las campañas de vacunación, dirigidas a mujeres en edad fértil.