A new vaccine that has the potential to be the first to prevent maternal and congenital cytomegalovirus (CMV) infection was detailed in a study published in the March 19 edition of the New England Journal of Medicine. Dr. Larry Corey, co-director of the Hutchinson Center’s Vaccine and Infectious Disease Institute, and Dr. Meei-li Huang, of VIDI and a research scientist in the Virology Division at the University of Washington and an affiliate member in VIDI, were co-authors of the paper with colleagues at the University of Alabama at Birmingham, who led the study.
Each year in the U.S., nearly 30,000 babies are born with congenital CMV, the most common virus transmitted by a pregnant woman to her unborn child, and nearly 8,000 of these children suffer permanent hearing, cognitive or motor impairments.
Although the first vaccine trials for CMV took place nearly 30 years ago, an effective vaccine has remained elusive.
"The most striking result from this study is that the vaccine showed efficacy in the mothers, and is the first to do so," said Dr. Robert Pass, lead author and professor in the UAB Department of Pediatrics.
In a phase 2 clinical trial, researchers looked at 441 CMV-negative women who received either the vaccine or a placebo within one year of giving birth. The trial evaluated an experimental vaccine made from a single CMV protein, glycoprotein B, which is known to induce an immune response. The vaccine, supplied by Sanofi Pasteur, included an experimental adjuvant, MF59, supplied by Novartis. An adjuvant is a substance added to a vaccine to improve the immune system response it elicits. Women who received the vaccine were significantly more likely to remain uninfected throughout the 42-month follow-up period than those who received the placebo. Eight percent of vaccine recipients eventually became infected with CMV, while 14 percent of placebo recipients acquired a CMV infection by the time of the interim analysis conducted once all participants had at least 6 month follow-up after the last study vaccine dose. The CMV polymerase chain reaction that Drs. Huang and Corey developed was utilized for defining the CMV endpoints in the trial.
A larger phase 3 trial is needed to confirm the efficacy of the vaccine.
The National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, sponsored the trial.