NEW YORK (Reuters Health) – A cytomegalovirus (CMV) vaccine reduces incident cases of CMV infection in women and has the potential to decrease congenital CMV infection, according to a report in The New England Journal of Medicine for March 19.

The authors note that congenital CMV infection is an important cause of neonatal neurological impairment. “On the basis of a cost-effectiveness analysis, the development of a vaccine for the prevention of congential CMV infection was listed as a top priority for the US by a committee of the Institute of Medicine in 2001,” lead author Dr. Robert F. Pass, from the University of Alabama, Birmingham, and colleagues point out.

Finding an effective CMV vaccine, however, has been a challenge. The first trials of a CMV vaccine began over three decades ago and still one has not been developed with suitable safety and efficacy.

In the present placebo-controlled trial, the researchers tested a vaccine containing recombinant CMV envelope protein B with MF59 adjuvant. A total of 464 non-pregnant, CMV-seronegative women, between 14 and 40 years of age, were randomized to receive doses of the vaccine or placebo at 0, 1, 6 months after they had given birth.

During at least 1 year of follow-up, 18 CMV infections were seen in the vaccine group compared with 31 in the placebo group. Further analysis confirmed that women given the vaccine were significantly more likely to remain uninfected during 42 months of follow-up (p = 0.02). Based on infection rates per 100 person-years, the vaccine was 50% effective.

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.

Local reactions, such as pain and erythema, as well as systemic reactions, like chills and arthralgias, were more common in the vaccine group than in controls, the authors note.

In a related editorial, Dr. Cornelia L. Dekker and Dr. Ann M. Arvin, from Stanford University School of Medicine, California, note that although side effects were more common with the active vaccine, they were generally mild in nature and, therefore, further studies of the vaccine are acceptable.

Further research, they add, is also needed to determine if the immune response provided by the vaccine is durable and on par with that of naturally acquired CMV immunity.

N Engl J Med 2009;360:1191-1199,1250-1252.