Vaccine for Carcinoma Cervix

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Vaccine for Carcinoma Cervix

Introduction

The cervix is a fibromuscular organ that communicates the uterine cavity with a vagina. Cancer to this part of an organ is considered as cancer cervix. Cancer Cervix is a global health problem and it is most prevalent in countries with poor socioeconomic status.

Long lasting infection with certain strains of Human Papilloma Virus (HPV) infection is the main cause of cervical cancer

HPV vaccine stimulates the body to produce antibodies that in the future when encounters with the virus prevent it from infecting cells. The current HPV vaccines are based on virus-like particles that are prepared from HPV surface particles.

There are about 14 high risks HPV types which cause Cancer Cervix. The HPV Strains include 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66 and 68. Among theses the HPV 16 and HPV 18 take part in causing cancer most of the time.

Here lies the scope HPV vaccines to prevent HPV infections. There are studies which confirmed that HPV vaccination in women drastically reduced the incidence of cervical cancer.

Researchers in Sweden confirmed it. They enrolled 1.7 million women and observed that Vaccine efficacy is more pronounced in girls vaccinated before the age of 17 and there is 90% reduction in the incidence rate. The HPV vaccines that were available at that time were against 4types of HPV viruses: HPV 6, 11, 16, and 18.

From the study it is concluded that the optimal age is pre pubertal. Preferably vaccine should be administered before exposure to HPV infection. According to WHO the defined age is 9-14 years of age. Indian guideline also recommends same age for vaccination against HPV infection for primary prevention. The schedule is two doses at 6 months interval. A single dose schedule also have equal efficacy as per WHO revised guideline. The revised guideline is as below:

WHO now recommends:

A one or two-dose schedule for girls aged 9-14 years
A one or two-dose schedule for girls and women aged 15-20 years
Two doses with a 6-month interval for women older than 21 years

Vaccines available against Cancer Cervix / HPV infection

Bivalent: Cervarix against HPV variant 16 and 18
Quadrivalent: Gardasil against HPV variant 6,11,16,18
Nonavalent: Gardasil 9: against HPV variant 6, 11, 16, 18, 31, 33, 45, 52 and 58

IAP schedule

Girls 9- 10 years: Two doses to be administered at an interval of 6 months, (0-6 months).
Girls 15 years and older: Three doses recommended in the schedule of 0 -1 -6 months for Cervarix and 0 -2 -6 months for Gardasil.
In immunocompromised individuals of any age: 3 doses recommended in the schedule 0 -1 -6 months for Cervarix and 0 -2 -6 months for Gardasil.
Gardasil 9 is scheduled in a three dose schedule of 0 -2 -6 months in females 9 -26 years of age and males 9-15 years of age.
The ideal age for starting the vaccine is 9-10 years.

Vaccines produced in India

Cervavac is the first indigenous vaccine soon to be available in the market. It is designed to prevent HPV strain 6, 11, 16,18.

Currently, Gardasil of Merck, an American multinational company, is available in India.

Efficacy of vaccine

Two phase III studies, FUTURE I and FUTURE II evaluated Gardasil and PATRICIA II evaluated Cervarix. FUTURE I study shows the quadrivalent vaccine significantly reduced the incidence of HPV-associated anogenital diseases in young women. FUTURE II and PATRICA II concludes in young women who had not been previously infected with HPV-16 or HPV-18 and those in the vaccine group had a significantly lower occurrence of high-grade cervical intraepithelial neoplasia related to HPV-16 or HPV-18 than did those in the placebo group.

In a randomized multicentre prospective trial, by Partha Basu published in lancet oncology, 2021, efficacy of quadrivalent HPV vaccine against HPV 16 and 18 infections among participants and found that a single dose of HPV Vaccine provides similar protection against persistent infection from HPV 16 & 18 to that provided by 2 or 3 doses.

Adverse effects and contraindications

The most common reactions are local like pain (mild to moderate), swelling with erythema, redness and systemic side effects such as fever, headache, and gastrointestinal symptoms including nausea, vomiting, diarrhea and abdominal pain. No serious vaccine related adverse events have been reported.

The vaccine is not recommended for pregnant women and is contraindicated in people with history of hypersensitivity to yeast or any vaccine component. People who are moderately or severely ill should usually wait until they recover, before getting HPV vaccine.

Conclusion

HPV vaccination is for primary prevention of carcinoma cervix. It does not treat or get rid of existing HPV infections that occurred before vaccination. Indian Academy of Pediatrics (IAP) Immunization schedule for 0-18 years recommends two doses of HPV vaccine for adolescent/pre-adolescent girls aged 9-14 years; for girls 15 years and older, current 3 dose schedule will continue. There is a need to raise awareness about the HPV infection and substantial percentage of cancers that are caused by this. Integration of cancer education and vaccination into every parents/caregiver into family agenda should be advocated and a strategy for long term follow up of vaccinated girls should be built. Parents/caregivers of child must be educated regarding HPV vaccination before offering this chemoprophylaxis against cervical cancer