An important cause of neurological impairment in newborns - infection with cytomegalovirus while they are in the womb - may be curbed with the use of a new vaccine. Most adults have been infected with cytomegalovirus or CMV, usually with negligible consequences. However, when pregnant women become infected with CMV for the first time, there is a danger that their baby will also be infected. In some cases, this congenital CMV infection can lead to permanent defects such as hearing loss, vision loss, mental disability, lack of coordination, or seizures. Finding an effective CMV vaccine has been a challenge even though the first trials of a CMV vaccine began over three decades ago. A study in America reports that a newly developed CMV vaccine reduces cases of CMV infection in women and has the potential to decrease congenital CMV infection. In the present trial, the researchers tested a vaccine containing a protein found on the envelope of cytomegalovirus and an adjuvant to increase the immune response. A total of 464 non-pregnant, CMV-negative women, between 14 and 40 years of age, were given three doses of the vaccine or an inactive "placebo" over a six-month period. During follow-up, 18 CMV infections were seen in the vaccine group compared with 31 in the placebo group. Ninety-seven women in the vaccine group and 118 in the placebo group became pregnant after vaccination. One congenital CMV infection occurred among 81 live births in the vaccine group, compared with 3 cases among 97 live births in the placebo group. Further analysis confirmed that women given the vaccine were significantly more likely to remain uninfected over a period of 42 months. Future studies would be required to show if this vaccine has reasonable efficacy, safety, and an acceptable level of reactogenicity before it can be considered useful in preventing CMV infection in young women and congenital CMV in their infants.
New England Journal of Medicine
March 2009