Vaccine is a substance introduced into the body to prevent infection or to control disease due to a certain pathogen. What is the need to have vaccines for sexually transmitted diseases (STDs)? The high health and economic costs of associated complications and the risk for carcinomas are some of the reasons why vaccines can be used in STDs. Besides the transmission of HIV is also increased in the presence of STDs. Vaccination is the most cost effective approach in the long term interventions to decrease STDs. Despite the fact that a number of vaccines have been developed, a still lot more are under various phase of trial. There are multiple hindrances at all levels of STD vaccine development. The problems associated with STD vaccines are that there can be change in the sexual behavior of the person. Parental acceptance is also necessary when vaccinating the minor. There are a number of STD vaccine candidates for development. STD vaccines can be live attenuated or killed. They can be used prophylactically or for therapeutic purposes. HBV is the STD vaccine first licensed for use. It is indicated for immunization against infection caused by all known subtypes of hepatitis B virus. It is given i.m on a 0, 1, 6 month schedule. It comes as EngerixB, Recombivax HB and Twinrix (HAV and HBV) in the market. It is recommended for all unvaccinated adolescents, all unvaccinated adults at risk for H BV infection and all adults seeking protection from HBV infection. Hepatitis A vaccine is FDA approved for persons aged> 12 months. It is given i.m as 2 doses (0, 6-12 months). It is available as Havrix and Vaqta. It is indicated for all MSM, Illegal drug users (both injecting and non injecting) and persons with chronic liver disease, including those with chronic Hepatitis B and Hepatitis C infection.

FDA licensed the first vaccine to prevent cervical carcinoma and other diseases caused by HPV. It is available as Gardasil and Cervarix. Gadasil is quadrivalent (HPV 6,11,16,18) and Cervarix is bivalent( 16,18). Gardasil is indicated in girls and women 9 through 26 years of age for

the prevention of the following diseases caused by Human Papillomavirus (HPV) types included in the vaccine:

Cervical, vulvar, vaginal, and anal cancer caused by HPVtypes 16 and 18

Genital warts (condyloma acuminata) caused

by HPV types 6 and 11

Cervical intraepithelial neoplasia (ClN) Vulvar intraepithelial neoplasia (VIN) Vaginal intraepithelial neoplasia (VaiN) Anal intraepithelial neoplasia (AIN)

It is also indicated in boys and men 9 through 26 years of age for the prevention of the following diseases caused by H PV types included in the vaccine:

Anal cancer caused by H PV types 16 and 18 Genital warts (condyloma acuminata) caused by HPV types 6 and I I Anal intraepithelial neoplasia (AIN)

There are numerous studies for therapeutic and prophylactic vaccines for HSV. They are yet to be adequately studied and efficacy tested. The greatest challenge while developing vaccine is that of HIV. There are multiple vaccines in different stages of trial. Is developing an HIV-1 vaccine possible? The success of the RV144 Thai HIV-1 efficacy trials with a replication-. defective recombinant canarypox vector (AlVAC)/gp 120 prime, clade B/E recombinant gp 120 protein boost showing 31 % efficacy has given hope that indeed a protective HIV-1 vaccine can be made.

The development of STD vaccine is not a substitute for protective sexual behaviour as it does not protect from all STDs. One should maintain confidentiality and give an informed choice to the patient while giving these vaccines.

 

Dr Chitralekha Keisham (MD Dermatology)