ADDITIONAL VACCINES RECOMMENDED BY IAP

In addition to vaccines discussed earlier, IAP also recommends some other vaccines, which are desirable in all children but current logistics preclude their inclusion in the NIS and have to be purchased by parents.

Human papillomavirus (HPV) vaccines: HPV is the commonest sexually transmitted infection in adolescents and adults, associated with development of genital warts and cervical, anogenital and oropharyngeal cancers in later life. High-risk serotypes 16 and 18 cause ~70% cases of cervical cancers.

India plans to introduce HPV vaccine soon in NIS, using an indigenously developed vaccine.

Contents: All HPV vaccines are recombinant vaccines differing in the number of serotypes. Currently, three types of HPV vaccines are available—a bivalent vaccine (HPV₂) containing serotypes 16 and 18, a quadrivalent vaccine (HPV₄) containing four serotypes 6, 11, 16 and 18 and a nonavalent vaccine (HPV₉) containing nine serotypes. First indigenous HPV₄ vaccine has also been launched in 2023, expected to be used in NIS.

Supply and storage: All HPV vaccines are single dose 0.5 ml ready-to-use suspension, which must be stored at 2-8°C and not be frozen.

Dosage and administration: 0.5 ml/dose IM for all HPV vaccines.

Immunization schedule: In India, HPV vaccines are licensed for use only in females from 9 years to 26 years of age, with 3 doses at 0, 1, 6 months (for HPV₂) or 0, 2, 6 months (for HPV₄ and ₉).

However, IAP recommends 2-dose schedule at 0, 6 months in girls lt; 15 years, which is equally immunogenic. For older or immunocompromized girls, standard 3-dose schedule is recommended.

NIS plans to introduce indigenous HPV₄ in two-dose schedule for girls aged 9-14 years.

IAP also recommends two doses of HPV₉ or Indigenous HPV₄ at six month interval to all boys aged 9-14 years to prevent genital warts and anogenital cancers (not beyond 14 years).

Protective value: All vaccines are equally immunogenic with ~90% protection against HPV infection/disease due to vaccine serotypes in females, not infected till the time of vaccination. Pre-adolescent immunization is superior to the immunization in older females as the vaccine does not alter outcome of HPV16/18 infection already acquired before vaccination.

Side-effects are rare except mild fever and local reactions. Syncopal attacks are common in adolescent girls, who must be observed for 30 minutes after vaccination.

Contraindications are none except allergic reaction to previous dose and should be avoided during pregnancy. Typhoid vaccine: In India, two types of typhoid vaccines are available, both active against Vi-capsular polysaccharide antigen: (a) polysaccharide vaccine (TPSV), and (b) conjugate vaccine (TCV), using a carrier protein, e.g. tetanus or diphtheria toxoid to boost its immunogenicity.

Contents: All TPSVs contains 25 #956;g/dose of capsular Vi antigens, while antigenic dose in TCV varies 5 to 25 pg/dose.

Supply and storage: All vaccines are supplied as single dose vials, to be stored at 2-8°C.

Dosage and administration: All vaccines are given as 0.5 ml/dose IM or deep SC.

Immunization schedule: Not included in NIS, IAP recommends a single dose of TCV to all children at 6-9 months of age, with catch-up immunization up to 18 years.

TPSV is no longer preferred due to poor immunogenicity of polysaccharide vaccines in children lt; 2 years and need for revaccination every 3-5 years.

Protective value of TCV is gt;98% after 42 days of vaccination. While antibody titers decline with time, all vaccinees are protected for 3-5 years and then, the immunity is expected to be further boosted due to subclinical natural infections.

Despite the high seroconversion rate of gt;98% after TPSV vaccination, protective efficacy is only 55-70% for 2-3 years.

Side-effects are rare, except local pain and erythema. Vaccines do not interfere with widal test reports.

Contraindications: None, except past history of allergy. Hepatitis A vaccine (HAV): While recommended by the IAP to all children, HAV vaccine is particularly important in high-risk children, e.g. those with chronic liver disease, hepatitis B/C carriers, immunodeficiency states, transplant recipients, institutionalized children and travelers to endemic regions. HAV vaccine can also be used for post-exposure prophylaxis in household contacts of a case, when given within 10 days.

Contents: Two types of HAV vaccines are available in India—inactivated vaccines derived from HM 175/GBM or RG-SB strain and a live attenuated vaccine derived from the H2 strain. It is also available as a combination vaccine with HBV.

Supply and storage: Inactivated vaccines are liquid and ready to use, available in different formulations for children (0.5 ml) and adults (1.0 ml). Live attenuated vaccine is a freeze-dried vaccine, to be reconstituted before use. All vaccines need to be stored at 2-8°C.

Dosage and administration: Inactivated vaccines are given IM as 0.5 ml in children and 1.0 ml in adults gt;19 years. Live attenuated vaccine is given as 0.5 ml SC.

Schedule: Not included in NIS, IAP recommends either two dose of inactivated HAV 6-18 months apart during 12 to 23 months of age or only a single dose of live vaccine at 12 months age. Catch-up immunization is recommended till 10 years.

For catch-up vaccination in older children/adolescents gt;10 years, IAP recommends pre-vaccination screening for HAV antibodies due to substantial chance of natural infection and immunity by this age.

Combined HAV+HBV vaccine needs three doses at 0, 1, and 6 months.

Protective value is gt;90-95% for at least 10 years with both vaccines, followed by natural boosting.

Side effects are uncommon, except mild fever and local reaction.

Contraindications are none, though dose should be deferred during acute severe febrile illness.

Varicella vaccine: IAP recommends varicella vaccine to all children without previous disease, with special emphasis in high-risk children, e.g. those with chronic lung/heart disease, immunocompromised states and institutionalized children attending creches, day-care centers, or orphanages. It may also be used for post­exposure prophylaxis in contacts of a case, when given within 3 days of exposure.

Contents: It is a live-attenuated vaccine, prepared from Oka strain of varicella-zoster virus, with each dose containing minimum 1350 PFU (plaque forming units) organisms.

Supply and storage: It is supplied as a single-dose lyophilized powder with diluent, which should be stored at 2-8°C.

Dosage and administration: 0.5 ml subcutaneously (not IM).

Immunization schedule: IAP recommends two doses - first at 15-18 months and second after 3-6 months of the first dose. High-risk children may be given two doses at shorter interval of 8 weeks.

Catch-up immunization is recommended till 18 years with two doses at 8-12 weeks interval.

Protective value is ~85-90% with one dose and gt;98% with two doses, better for moderate to severe disease than mild disease. Varicella vaccine is also known to reduce the incidence of herpes zoster by ~50% in adults. Side-effects are mild and transient, including local reactions. Some children may develop transient and mild papulovesicular eruptions after 1-3 weeks, termed as modified varicella like illness or MVLI.

Breakthrough varicella, usually with milder disease, has been reported gt;6 weeks following immunization in 1-4% vaccines, specially those vaccinated lt;15 months of age or in late childhood.

Herpes zoster is also known to occur with vaccine, but incidence is far less than in unvaccinated children.

Contraindications: Being a live vaccine, it should not be given to severely immunocompromised children or during pregnancy. Salicylates should be avoided for 6 weeks post-vaccination due to potential risk of Reye syndrome.

Influenza vaccines: IAP recommends influenza vaccine to all children annually from 6 months to 5 years of age and to high-risk children beyond this age including those with immunodeficiency states, diabetes or chronic cardiac, pulmonary, hematologic, renal or liver disease. Contents: All available influenza vaccines in India are trivalent or quadrivalent inactivated vaccines (IIV), containing two serotypes A and one or two serotypes B viral strains, recommended by WHO annually, depen­ding on prevalent strains in previous season. All vaccines include Pandemic 2009 H1N1 strain. Live attenuated influenza vaccines are available, but not in India.

Biologically, IIV are either split-virion or sub-unit vaccines, produced from highly purified and inactivated virus grown on embryonated hen eggs.

Composition of the influenza vaccines is changed annualy due to phenomena of antigenic shift and drift (Ch 10.26). WHO recommends two different set of vaccine strains every year-one for northern hemisphere in February and another for southern hemisphere countries in September. While entire India is in northern hemisphere, southern hemisphere vaccines are considered as more appropriate here, especially for south India.

Supply and storage: IIVs contain 7.5 or 15 #956;g hemag­glutinin of each component strain, supplied as 0.25 or 0.5 ml single-dose vials or prefilled syringes, to be stored at 2-8°C.

Dosage and administration: IAP recommends a uniform dose of 0.5 ml for all children above 6 months of age, though some manufacturers recommend a lower dose of 0.25 ml in children lt;3 years due to higher reactogenicity and risk of febrile seizures in younger age group.

Immunization schedule: Not included in NIS, IAP recommends Influenza vaccination to all children from 6 months to 5 years of age, and in high-risk children beyond this age. Two doses at 4 weeks interval are recommended in first year of vaccination in children lt;9 years, followed by a single dose annually preferably just before the onset of peak influenza season. In children aged 9 years or above, adolescents or adults, only single dose is recommended, even if not vaccinated earlier

Protective efficacy: Reported efficacy of IIVs is ~59% for confirmed influenza and 36% for all influenza-like- illnesses, for one year.

Side-effects: IIVs are generally safe except for local reactions, higher risk of febrile seizures and rare risk of Guillain-Barre syndrome in some cases.

Contraindications: IIVs should be avoided in cases with egg allergy or past history of Guillain-Barre syndrome, unless expected benefits outweigh risks.

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