Valaciclovir prophylaxis to prevent recurrent herpes at delivery

Valaciclovir prophylaxis is tolerated well in late pregnancy, has no adverse effects on the neonate and significantly reduces clinical recurrences at delivery, laboratory detection of HSV at delivery, and caesarean delivery for HSV

What's known?

• Although only 5% to 10% of women of reproductive age have a history of genital herpes infection, 25% to 30% have HSV-2 antibodies in the United States.
• The majority of these seropositive women are unaware of their HSV infection.
• As the incidence of HSV infections continues to rise, and because the greatest incidence of HSV infections occur in women of reproductive age, the risk of maternal transmission of the virus to the foetus or neonate has become a major health concern in the USA.
• Five to 10% of pregnant women have symptomatic recurrent genital herpes during pregnancy and up to 25% of these women will have an HSV outbreak the last month of pregnancy.
• One to 2% of pregnant women with a history of recurrent HSV infection have asymptomatic shedding at the time of delivery.
• However, studies from antenatal clinics in Australia have shown that HSV-2 antibodies can be detected in 12-15% of pregnant women and neonatal herpes is very rare in Australia.

What’s new?

All the 350 eligible women had serologic confirmation of prior HSV infection by antibody testing using an HSV-1 and HSV-2 IgG enzyme-linked immunosorbent assay.

• The purpose of this study was to estimate the efficacy of valaciclovir prophylaxis given from 36 weeks gestation until delivery in reducing clinical and virologic evidence of HSV infection at the time of delivery.
• Overall, 82% of the women had recurrent genital herpes; 12% had first episode, non-primary genital herpes; 6% had first episode, primary genital herpes.
• Each patient was examined for clinical evidence of genital herpes and vulvovaginal specimens were collected during labour for HSV culture and PCR testing.
• Valaciclovir significantly reduced the number of women with clinical genital HSV at delivery by 70%, 13% in the placebo group compared to 4% in the valaciclovir group (p = .009; OR .30, 95% CI .12-.73).
• Valaciclovir significantly decreased the likelihood of a positive culture or PCR result (p = .02 and 0.01, respectively).
• In this study, valaciclovir also decreased the number of caesarean deliveries performed for HSV, from 13% in the placebo group to 4% in the valaciclovir group (p = .009). It should be noted that even with valaciclovir, some women still have recurrences and may require caesarean section.
• There was no significant increase in adverse obstetric or neonatal events in the valaciclovir group.
• The investigators concluded that valaciclovir prophylaxis was tolerated well in late pregnancy, had no adverse effects on the neonate and significantly reduced clinical recurrences at delivery, laboratory detection of HSV at delivery, and caesarean delivery for HSV.
• The authors also stated that 11 women would need to be treated with valaciclovir to prevent 1 caesarean delivery for HSV.