This is a kind
of first vaccine that is given in infancy to eliminate the disease in
adults.337 Children born to mothers who are positive for HBs
antigen
should receive HBIG in addition to full HBV vaccination in order to protect
them from risk of chronic infection in case they have acquired infection from
the mother. Certain individuals known as non responders fail to mount humoral
antibody response following vaccination and would therefore be requiring repeat
vaccination as per CDC recommendations 5. The current vaccination programme
has many limitations like multiple parenteral doses, problem of non responders
(10%), infection by escape mutants despite adequate vaccine response and
finally high cost of vaccination especially for developing nations. Some of these
limitations are now being addressed with attempts to combine HBV vaccine with
other vaccines thereby decreasing the number of required doses and also
research for oral vaccines is underway that may obviate the need for trained
personnel for parenteral administration of vaccines 36.

Vaccine against HPV

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Cervical
cancer is the fifth most common cancer occurring in humans and the second most
common cancer in women worldwide. Infection by high-risk types of HPV (16 and
18) contributes to more than 70% of all cervical cancer cases. Certain non-oncogenic
HPV serotypes (6 and 11) also contribute to more than 90% in occurrence of benign
genital diseases such as genital warts 8. Cancer cervix is one of the most
common cause of cancer death in the developing nations and unlike many cancers,
it strikes early during the productive period of a woman’s life. This is the
reason why the preventive strategies should start at an early age long before
the first sexual exposure. Routine screening procedures being followed in
developing countries like India are not of much use and estimates suggest that
more than 80% of the sexually active women acquire genital HPV by 50 years of
age.3 Hence is the importance of vaccination against HPV oncogenic serotypes
at an early age to protect from cancerous consequences later in life. 13 V But
HPV immunization rates are substantially lower than rates of other childhood
and adolescent immunizations. In addition to cost and parental concerns about
vaccine safety, barriers to HPV vaccine uptake among adolescents and young
adults include the misperceptions among some parents that HPV immunization is
not needed for children who are not sexually active and that the receipt of the
vaccine might increase promiscuity.65 Strategies to increase HPV vaccination
include reminder/recall systems; practice focused interventions targeting
staff, clinicians, and parents; assessment and feedback activities; and
school-based HPV vaccination programs.66Vacci

HPV
vaccination is important for pediatric, adolescent, and young adult cancer
survivors because of the increased incidence of subsequent HPV-associated
malignancies among long-term survivors.67Vaccii The excellent antibody
response and high level among young children suggest that the best time to
initiate the vaccine series is before the exposure to HPV infection (i.e. prior
to sexual debut). This information, combined with the fact that acquisition of
HPV infection at a younger age (18 years) and post infection to
have a cancerous conclusion 20 years later, makes vaccination of young children
a high priority 337

A
total of three HPV vaccines are available that have got FDA approval to be used
in routine practice. These three vaccines are: Gardasil, Gardasil 9, and
Cevarix. Two among these vaccines are available in India- a quadrivalent
vaccine (Gardasil™ marketed by Merck) and a bivalent vaccine (Cervarix™
marketed by Glaxo Smith Kline).18 All three vaccines prevent diseases caused
by HPV types 16 and 18, which are responsible for about 70% of cervical
cancers. Gardasil and Gardasil 9 also prevent against diseases due to HPV types
6 and 11. These vaccines are manufactured by recombinant DNA technology that
produces non-infectious virus like particles (VLPs) comprising mainly HPV L1
protein. These vaccines however, do not protect against the HPV serotypes
acquired before vaccination.

Cervarix
is a mixture of L1 proteins of HPV serotypes 16 and 18 with aluminium sulphate
as an adjuvant and has shown 90% efficacy in clinical trials with three doses given
at 0, 1 and 6 months in providing protection against type 16/18-related CIN-2/3
and AIS. No evidence of waning immunity was observed 20 but this vaccine
protects only against cervical cancers.

Gardasil is composed of L1 proteins from four
HPV serotypes (16, 18, 6, 11) and have shown 100 % efficacy in the clinical
trials reported from five continents including Asia against types 16/18-related
CIN-2/3 and AIS. The three dosing schedule given at 0, 2, 6 months in women
aged 16-26 years 337 protects from almost 100% vaginal, cervical, and vulval
cancers and genital warts.

Gardasil 9 (6, 11, 16, 18, 31, 33, 45, 52,
and 58), the newest vaccine, has shown 97% efficacy in preventing all HPV
associated cancers (except oropharyngeal cancer). It has been approved to be
used in people aged between 9-26 years.

HPV
vaccination is recommended as a 2-dose schedule (at least 6 months apart) for
children who initiate vaccination between the ages of 9 through 14 years,
whereas 3 doses (at baseline, 1 to 2 months, and 6 months later) are
recommended for immunocompromised persons and for individuals who initiate the
vaccination series at ages 15 through 26 years. Vacci The vaccine dose is 0.5
ml given intramuscularly, either in the deltoid muscle or in the antero-lateral
thigh. It is available as a sterile suspension for injection in a single-dose
vial or a prefilled syringe, which should be shaken well before use. Till date,
none of the vaccines are currently approved to prevent oropharyngeal cancers,
but it would not be surprising if future data prove that these cancers would be
prevented too with current vaccination. HPV vaccines can be given
simultaneously with other vaccines such as Hepatitis B and Tdap.13 V

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