Potential benefits of a serodiagnostic test for herpes simplex virus type 1 (HSV-1) to prevent neonatal HSV-1 infection

Background: Changes in sexual practices have led to an increase in the incidence of genital herpes simplex virus type 1 (HSV-1) infections. Such infections affect an estimated 400 newborns each year, with serious consequences. Goal: To evaluate the use of a serodiagnostic test for HSV-1 to be used by pregnant women, and possibly their sexual partners, in preventing neonatal HSV-1 infections by identifying seronegative (at-risk) women. Study Design: The number of cases of neonatal HSV-1 prevented by a test of a given sensitivity and specificity is estimated using two simple models parameterized with data from published sources. Results: Used by women only, a 90%-specific test for HSV-1 could avert 71%-90% of the expected cases of infection among women using the test, requiring about 14,000 tests per case averted. This result depends linearly on the specificity of the test and does not depend on the sensitivity. Use by women and their partners results in more tests for the same benefit (about 24,000 tests per case averted if the test is 90% sensitive and 90% specific), because the only additional information provided by testing the partner of an at-risk woman is to determine that her partner may not be HSV-1 positive. Conclusions: The key feature of such a diagnostic test is its specificity; its use to identify at-risk women could provide public health benefits if the specificity exceeds 70%, but these benefits would increase dramatically for higher specificities. Use of such a test for couples is likely to be more costly and less effective than testing women only.