it is theoretically possible to develop a vaccination program aimed at pubertal females, similar to that in the United Kingdom for congenital rubella, difficulties may be encountered in achieving high immunization rates in that group. Some health professionals favor the strategy of administering a CMV vaccine simultaneously with current pediatric vaccines.
For seronegative persons who are going to receive a transplant from a seropositive donor and individuals with leukemias and lymphomas (subsequently referred to as “high-risk individuals”), it would seem desirable to offer some degree of protection against primary infection. Studies are underway in transplant recipients using the Towne live attenuated vaccine developed by Plotkin (Plotkin et al., 1984). The preliminary report on these studies indicates that of those vaccinated, 15 out of 16 seronegative recipients of renal transplants from seropositive donors had evidence of infection following transplantation, and nine manifested evidence of cytomegalovirus disease. Eleven of the 14 placebo recipients had evidence of infection and 10 showed clinical manifestations of CMV infection. The infection rate and the percentage of those infected showing symptoms did not differ significantly between the vaccine-treated and placebo-treated groups; however, a significantly higher percentage of placebo recipients showed evidence of severe CMV disease.
These preliminary studies suggest that this high-risk population is an appropriate, discrete target population (albeit small) to consider in CMV vaccine development.
CMV infection occurs over a wide age range, so an effective vaccination program would have to involve either a vaccine that provides very long lasting protection or boosters at regular intervals. The need for frequent boosters, which is more likely with a subunit vaccine, could decrease utilization rates.
It appears that the best method for reducing the impact of congenital cytomegalovirus infection would be the induction of long lasting immunity in childhood. This would prevent primary infection during pregnancy. Immunization of pubertal females also would be effective if a high rate of vaccination could be achieved.