Herpes Vaccine Update: Exciting News, But Don't Throw Away Condoms Just Yet

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Earlier this year, I wrote about GEN-003, the world's first effective genital herpes vaccine (1). Since that time, our readers have expressed considerable interest in the clinical progression of this vaccine. So, as your "one-stop herpes resource supercenter" (probably not something you'd want inscribed on your gravestone), we have been following this vaccine and other developments in the field.

This week, there are some preliminary, but nonetheless very interesting developments; this time with a different vaccine (two, actually). Rational Vaccines (RVx), a biotechnology startup founded in 2015, focuses on vaccines for both genital and oral herpes simplex virus (HSV), which may be up to 100 times more effective than GEN-003. 

The vaccines are based on research performed by Chief Science Officer William Halford, Ph.D., Associate Professor at the Southern Illinois University School of Medicine. Halford, a virology and immunology expert, has taken a new approach by developing a new class of live HSV-1 and HSV-2 mutant vaccines called Theravax and Profavax. The key difference between Rational Vaccines' technology and previous herpes vaccines is referred to as antigenic breadth - the degree to which the vaccines resemble the outer coating of the virus found in naturally occurring HSV. The closer the match, the better the chances of eliciting a robust immune response.

Despite the absence of any testing in people, it is not such a stretch to predict that Rational may have a game changer on its hands (2).

I spoke with Agustin Fernandez III, founder and CEO of the company. Mr. Fernandez could not reveal the complete details of the vaccine because a press release is expected in mid-October. At that time, I will interview Dr. Halford, and provide more details.

Although still early in the approval process, Rational's vaccine, in my opinion, gets high marks. This is because the animal model of viral or bacterial infections in immune compromised (SCID) mice is generally quite predictive of efficacy in humans (3). And, its vaccines work like gangbusters in this model. Normally, when immune compromised mice are infected with herpes, they die. However, when the mice were first inoculated with the vaccine, 114 out of 115 survived after being infected with HSV-2. 

There are numerous indications that these vaccines may work better than GEN-003. We will know much more in a couple of weeks. Stay tuned. 


(1) GEN-003 has been shown to be moderately effective in phase II trials in treating people who are already infected with HSV-2, but it is not approved for use. 

(2) This is despite long odds. Only about 10 percent of drug candidates that enter human clinical trials end up being approved by the FDA.

(3) Animal models of human disease vary greatly in predicting the success of a potential drug in humans. Some models, for example, cancer and Alzheimer's, are terrible. Models for infectious disease are usually quite good.