Vaccine prevention of maternal cytomegalovirus infection

Abstract

Background: Congenital infection with cytomegalovirus (CMV) is an important cause of hearing, cognitive, and motor impairments in newborns.

Methods: In this phase 2, placebo-controlled, randomized, double-blind trial, we evaluated a vaccine consisting of recombinant CMV envelope glycoprotein B with MF59 adjuvant, as compared with placebo. Three doses of the CMV vaccine or placebo were given at 0, 1, and 6 months to CMV-seronegative women within 1 year after they had given birth. We tested for CMV infection in the women in quarterly tests during a 42-month period, using an assay for IgG antibodies against CMV proteins other than glycoprotein B. Infection was confirmed by virus culture or immunoblotting. The primary end point was the time until the detection of CMV infection.

Results: We randomly assigned 234 subjects to receive the CMV vaccine and 230 subjects to receive placebo. A scheduled interim analysis led to a stopping recommendation because of vaccine efficacy. After a minimum of 1 year of follow-up, there were 49 confirmed infections, 18 in the vaccine group and 31 in the placebo group. Kaplan-Meier analysis showed that the vaccine group was more likely to remain uninfected during a 42-month period than the placebo group (P=0.02). Vaccine efficacy was 50% (95% confidence interval, 7 to 73) on the basis of infection rates per 100 person-years. One congenital infection among infants of the subjects occurred in the vaccine group, and three infections occurred in the placebo group. There were more local reactions (pain, erythema, induration, and warmth) and systemic reactions (chills, arthralgias, and myalgias) in the vaccine group than in the placebo group.

Conclusions: CMV glycoprotein B vaccine has the potential to decrease incident cases of maternal and congenital CMV infection. (ClinicalTrials.gov number, NCT00125502.)

2009 Massachusetts Medical Society

Figures

Figure 1. Enrollment and Outcomes

In the vaccine group, 47 subjects did not receive the full three doses of vaccine because 4 were lost to follow-up, 5 had an adverse event, 7 had a compliance issue, 5 withdrew from the study, 2 were found to have CMV infection, 6 became pregnant, and 18 were unable to receive the vaccine owing to its unavailability. In the placebo group, 60 subjects did not receive three doses of placebo because 16 were lost to follow-up, 2 had an adverse event, 4 had a compliance issue, 4 withdrew from the study, 4 were found to have CMV infection, 13 became pregnant, and 17 were unable to receive placebo owing to its unavailability.

Figure 2. Kaplan-Meier Estimates of Probability of Remaining Free of CMV Infection

Up to 42 months after study enrollment, subjects in the vaccine group were more likely to remain free of CMV infection than were subjects in the placebo group (P = 0.02). In the vaccine group, 18 subjects were found to have CMV infection, as compared with 31 in the placebo group.