Incidence of Cytomegalovirus Primary and Secondary Infection in Adolescent Girls: Results From a Prospective Study.

Cytomegalovirus (CMV) can be passed from a woman to her unborn baby during pregnancy, which can result in disabilities in the baby. This can happen after a first infection with the virus during pregnancy, after a subsequent infection with a different strain ("reinfection"), or after "reactivation", which means that a virus present from a previous infection becomes active again. Vaccinating adolescent girls against CMV may be a future strategy to help prevent CMV infection during pregnancy. To provide information to design trials evaluating a CMV vaccine, it is important to know how common primary/secondary CMV infection is in adolescent girls and if this can be measured with available tools. We followed adolescent girls living in Finland, Mexico or the United States for three years. At study start, 58% of these girls showed evidence of previous CMV infection. During the three-year follow-up, a first CMV infection occurred in 15% of girls, and reinfection or reactivation in 6% to 24% of girls (depending on the method used). The obtained estimates of CMV infection rates in adolescent girls provide valuable information for future studies to evaluate CMV vaccines, but standardized markers for secondary infection are needed.