2. Combined Veccination Against Hepatitis A & Hepatitis B The Rationale For a combine Hepatitis A/B Vaccine. Twinrix Twinrix is a vaccine which combines the Antigen used in Havrix and Engerix-B it is effective in preventing Hepatitis A, Hepatitis B and Hepatitis D (Since Hepatitis D Virus depends for its existence on the presence of HBV.

3. Twinrix is a combine Vaccine containing antigen identical to those used in Havrix and Engerix B. These are purified inactivated Hepatitis A virus and genetically – engineered Hepatitis B surface antigen. (HBsAg) Twinrix Pediatric contains 360 ELU of Hepatitis A virus antigen and 10 µg of HBsAg. In.5 ml of water for injection. Twinrix Adult contains 720 ELU of Hepatitis A virus antigen and 10 µg of HBsAg. In.1 ml of water for injection. The antigens are adsorbed on to aluminum hydroxide and aluminum phosphate. The vaccine also contains the anti – microbial agent 2- phenoxyethanol and sodium chloride. Twinrix

4. DOSAGE AND VACCINATION SCHEDULES The recommended dosage of Twinrix pediatric is 0.5 ml. The recommended dosage of Twinrix adult is 1 ml. The standard primary course of vaccination consists of three dosage the 1 st administered at elected that, the 2 nd one month later and the 3 rd 6 months after first dose. Twinrix

5. MMR-Varicella DTPa-IPV-Hib-Hep B A combination formulation incorporating 6 antigens is also now developed. Preliminary data has indicated the immune response to the combination vaccine including Diphtheria, acellular pertussis, tetanus, Hepatitis B and inactivated polio viruses and Hib are comparable with those seen when vaccines are administered separately. COMBINATION VACCINE UNDER DEVELOPMENT

6. There is no doubt the coming era in vaccinology belongs to the new and wonderful concept of combination vaccine Spectacular Advances made in vaccine productions especially in the field of molecular biology and genetic engineering are revolutionizing the concept of child hood immunization. The future naked DNA gene vaccines the available in more combination formulation. NEW THINKING AND RE THINKING ON COMBINATION VACCINE