We appreciate the concern of the author on the affordability of Tdap for adolescents and adults of all strata of society. The Indian Academy of Pediatrics – Advisory Committee on Vaccines and Immunization Practices (IAP-ACVIP) would urge the manufacturers to provide an affordable vaccine to prevent pertussis in adolescents and adults. One Indian manufacturer is likely to come up with a Tdap vaccine that may bring down the cost. Moreover, when vaccines (or any other drugs) are used in large quantities, their cost go down markedly. IAP-ACVIP thus recommends Tdap vaccination in all adolescents [1], and would recommend it in routine immunization program too.

Typhoid vaccine has emerged as an effective tool to control typhoid fever especially in communities with high incidence of disease. TCV is better than Typhoid Polysaccharide Vaccines (TPV) as it can be administered in children aged between 6 months and 2 years, and has longer duration of action [2]. Repeated doses of TPV do not boost immune response and natural infection does not always boost immune response to TPV. TCV has been found to have efficacy not-inferior to that of TPV in human exposure trial in adults where efficacy of TCV was 54.6% (95%CI 26.8-71.8) and that of TPV was 52.0% (95%CI 23.2-70.0) [3].

When TCV is recommended at 6 months of age there will not be any need of TPV. However, those who have received the TPV earlier can also be given TCV after a minimum of 4 weeks after TPV administration. Although no such studies are available in this regard, this interval is likely to avoid any interference with immune response to TCV.

Benefits of vaccines should not be denied to any individual for lack of resources and the need of the affordable vaccines cannot be over emphasized in the current time. New recommendation on TCV is not likely to reduce the coverage as only single dose is recommended as of now whereas TPV needs to be given every 3 years. Moreover, TPV cannot be used to provide protection in children up to 2 years of age. Rather, the number of people receiving typhoid vaccine will become higher as new recipients (children up to 2 years of age) will receive TCV. Typhoid vaccination is also expected to serve as an important tool to curb antimicrobial resistance. Large-scale, more aggressive typhoid vaccination programs in children up to 15 years of age have the potential to reduce the overuse of antimicrobials, thereby reducing antimicrobial,　resistance　in many bacterial pathogens [4].

1. Balasubramanian S, Shah A, Pemde HK, Chatterjee P, Shivananda S, Guduru VK, et al. Indian Academy of Pediatrics (IAP) Advisory Committee on Vaccines and Immunization Practices (ACVIP) Recommended Immunization Schedule (2018-19) and Update on Immunization for Children Aged 0 through 18 years. Indian Pediatr. 2018;55:1066-74.

2. Michel R, Garnotel E, Spiegel A, Morillon M, Saliou P, Boutin JP. Outbreak of typhoid fever in vaccinated members of the French Armed Forces in the Ivory Coast. Eur J Epidemiol. 2005;20:635-42.

3. Jin C, Gibani MM, Moore M, Juel HB, Jones E, Meiring J, et al. Efficacy and immunogenicity of a Vi-tetanus toxoid conjugate vaccine in the prevention of typhoid fever using a controlled human infection model of Salmonella Typhi: a randomised controlled, phase 2b trial. Lancet. 2017;390(10111):2472-80.