INTRODUCTION
When Edward Jenner first administered smallpox vaccine in 1796, the process was known as variolation. Later came the use of the term vaccination, which was widely accepted. The term immunization came into vogue in due course to emphasize the importance of active immunity induced by various antigens. The Greek word Immune means to be protected. Whereas the protection offered by vaccines is active, passive protection is achieved by the administration of antisera or immunoglobulins. So, certain terminologies need to be defined carefully. Today both the terms vaccination and immunization are used interchangeably. However, the global practice is to use the term immunization more frequently viz, Expanded Program on Immunization (EPI), Universal Child Immunization (UCI), Global Alliance on Vaccines and Immunization (GAVI), etc.
After the discovery of smallpox vaccine in the year 1796, it took 79 years, for Louis Pasteur to develop the killed rabies vaccine in 1885 followed by the discovery of many more monovalent childhood antigens and the discovery of the first combination vaccine DTP in 1945 and measles, mumps and rubella combined vaccine, MMR, in 1971. With advances in genetic engineering and molecular biology the future will witness the development of more new antigens and perhaps most of these new antigens will be in combination formulation.
Immunization has rightly been claimed as the greatest success story in the history of mankind in the 20th century. Eradication of smallpox in 1978 had paved the way for the elimination/eradication of similar vaccine preventable 2diseases in several developed countries. Many developing countries like India too, have achieved outstanding success in eliminating VPDs like neonatal tetanus, diphtheria, pertussis, measles, poliomyelitis, etc. Global eradication of poliomyelitis by eradicating the circulation of wild as well as vaccine derived polio viruses is expected to be achieved by 2020.
GAVI, NTAGI, IEAG, IPEI RECOMMENDATIONS
Following repeated representations from the Indian Academy of Pediatrics, the Government of India has constituted a National Technical Advisory Group on Immunization (NTAGI) and India Experts Advisory Group (IEAG) which considers the exiting immunization practices and India Polio Eradication Initiative (IPEI) and AFP surveillance respectively and suggest introduction of a few more vaccines into the National Immunization Schedule and strategies to be adopted for polio eradication. It is fervently hoped that the laudable objective of All Vaccines for all the World's Children will become a reality soon.
The National Technical Advisory Group on Immunization since recommended the introduction of MR vaccine in the National Immunization schedule in place of measles vaccine as well as DTwP Booster in place of DT at 5 years. Apart from introducing the pentavalent fully liquid DTwP-HB-Hib vaccine throughout the country, introduction of rotavirus vaccine, one dose of IPV along with 3rd dose of PENTA and the switch to bivalent OPV viz. bOPV 1 and 3, replacing the conventional trivalent OPV viz. tOPV are in place already.
The Government of India has in principle approved the introduction of pneumococcal conjugate vaccine (PCV) in the National Immunization Program (NIP), with GAVI subsidy. Introduction of the rotavirus vaccine using the indigenous monovalent 116E strain is also being contemplated. Annual campaign with a single dose of JE vaccine in JE hyperendemic areas has been successfully implemented. Introduction of MR vaccine at 16–24 months along with DTwP booster and rubella vaccine at 10 years for adolescent girls are also in the agenda. A single dose of IPV along the 3rd dose of DTwP to enhance mucosal immunity, is also being considered as strategy towards Polio End 3Game. Switch from tOPV to bOPV for routine immunization and NIDs has already taken place.
DEVELOPMENT OF NEW VACCINES AND NEW TECHNIQUES FOR VACCINE ADMINISTRATION
Apart from the currently available toxin based, subunit, live organisms, inactivated organisms, polysaccharide, glycol-conjugate vaccines, etc. We will be having additional or replacement vaccines viz., anti-idiotype vaccines, re-assorted genomes, temperature sensitive mutants, recombinant viruses and bacteria, recombinant viral or bacterial vectors, genetic (DNA), plant (edible) vaccines, and transcutaneous vaccines which will revolutionize the concept of immunization.
In addition to development of new vaccines, new vaccine implementation and delivery strategies along with new developments in basic and applied immunology, including those directly related to vaccine biotechnology applied implementation, research and the bioethics of clinical trials promise to make the 21st century exciting for vaccinology. Developments such as whole genome sequencing may reveal entirely new paradigms for vaccine development. With molecular medicine's exorable advances, parallel research must progress to ensure that the scientific advances of developed countries are available in developing countries, as well.
LEARNING POINTS
Pediatric and Adolescent Immunization—yesterday, today and tomorrow:
Yesterday
Handful of vaccines, Expanded Program on Immunization (EPI), Targeted universal coverage of under 5 children and pregnant mothers, development of combination vaccine formulations, elimination and eradication of VPDs, smallpox eradication achieved.
Today
Pocketful of vaccines, EPI, Universal Child Immunization (UCI), Stress on Adolescent and Adult Immunization, 4More antigens for immunization during pregnancy, Global Program on Vaccines (GPV), Global Alliance for Vaccines and Immunization (GAVI), development of more combination vaccine formulations, newer adjuvants, newer technologies for vaccine development and administration, vaccine vial monitors to assess cold chain maintenance, elimination and eradication of VPDs viz. Eradication of poliomyelitis, control and elimination of neonatal and maternal tetanus diphtheria, pertussis, and measles have been achieved.
Tomorrow
Bagful of vaccines, all vaccines for all the world's children with GAVIs subsidy, more sophisticated combination vaccine formulations, needle free vaccine patches, more antigens for universal coverage, improved cold chain equipment, elimination and eradication of more VPDs, global eradication of poliomyelitis, neonatal and maternal tetanus, measles and many more.
BIBLIOGRAPHY
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