Skip to main content

Conflicting results from Herpes vaccine

Thumbnail
In this photo herpes simplex virions infect a tissue sample. A new vaccine shows promise in preventing infections from one type of herpes simplex, but not both. (Photo: CDC)

There are many types of Herpes viruses; including Herpes Simplex, Varicella Zoster (chickenpox causing virus), cytomegalovirus and many others. The types most people are familiar with are the ones which produce cold sores and genital herpes. Both of these manifestations are caused by the Herpes Simplex Viruses (HSV).

There are 2 types of HSVs: Type 1 and Type 2. The predominance of Type 1 associated with cold sores (or outbreaks above the neck) and the predominance of Type 2 with outbreaks in the anogenital region has led to the misconception that these viruses are limited to these respective anatomical locations. This is not true however; both types can lead to infection at either location. Indeed, they can even lead to local infection on the finger (herpetic whitlow) and many other anatomical regions as well.

The problem with HSV infections are that they are recurrent. Moreover, once infected, patients remain carriers for life. The virus remains dormant in nerve cells and can erupt during times of stress and immuno-suppression, but the exact patho-mechanism remains poorly understood.

Management of patients infected by either of these viruses is currently limited to antiviral medication which can shorten the duration and/or decrease the severity of symptoms. As a result there has been substantial interest in HSV disease prevention.

Recently an article published in the New England Journal of Medicine discussed how 2 previous vaccine studies showed a substantial effectiveness in preventing HSV-2 infection (73 percent and 74 percent) in HSV discordant couples (where 1 partner is infected and the other is not). These results prompted the authors to investigate the potential vaccine further.

The results were disappointing; they showed that HSV-type 2 which is the more prevalent cause of genital herpes was not prevented by the vaccine. This disappointment was echoed by a number of headlines in the media discussing the poor results. However, many have failed to point out the positives: Preventing genital herpes caused by HSV-1 was shown to have an effectiveness of 58 pecent. Though HSV-1 accounts for a minority of cases of anogenital herpes it is a partial victory nevertheless, and therefore deserves clear acknowledgment.

Date
Representative Image Caption
In this photo herpes simplex virions infect a tissue sample. A new vaccine shows promise in preventing infections from one type of herpes simplex, but not both. (Photo: CDC)
Blog Name