Low Risk of Herpes Simplex Virus Infections in Neonates Exposed to the Virus at the Time of Vaginal Delivery to Mothers with Recurrent Genital Herpes Simplex Virus Infections

TLDR

We studied the risk of HSV infection in neonates exposed to HSV during vaginal delivery to mothers with recurrent genital HSV infections. The study collected cord blood or early neonatal blood from 33 of 34 exposed, uninfected infants to assess neutralizing antibody. None of the 34 exposed infants acquired HSV, the 95 % confidence upper limit for the infection rate is 8 %, all 33 uninfected infants had detectable neutralizing antibody (79 % >1:20), infected infants had lower antibody levels, and these findings suggest neutralizing antibody protects against infection and empirical antiviral therapy is unnecessary. Published in N Engl J Med 1987; 316:240–4.

Abstract

We studied the risk of herpes simplex virus (HSV) infections in neonates exposed to HSV at the time of vaginal delivery to mothers with a history of recurrent genital HSV infections. None of 34 infants exposed to HSV type 2 acquired an HSV infection. On the basis of this sample, the 95 percent confidence limit for the theoretical maximum infection rate is 8 percent. Cord blood or blood obtained during the first two weeks of life was available from 33 of the 34 exposed, uninfected neonates. All 33 of the samples possessed demonstrable neutralizing antibody to HSV type 2, and 79 percent had titers above 1:20. These results were compared with those in a previously studied group of neonates with HSV infections; the latter infants were significantly less likely at the onset of symptoms to have demonstrable neutralizing antibody to HSV type 2 (P = 0.000148) or to have titers above 1:20 (P<0.00001). We conclude that given the low attack rate, empirical antiviral therapy is not warranted in all infants of mothers with recurrent genital HSV infection who are exposed to the virus in the birth canal. Our findings suggest that the presence and titer of neutralizing antibody to HSV contribute to the low attack rate. (N Engl J Med 1987; 316: 240–4.)