We thank the readers for their interest in our work [1] and provide the following clarifications: Regarding the inclusion criteria of participants, we wish to clarify that HIV-infected children aged 18 months - 12 years who had been receiving ART for at least 6 months and who had not received any prior dose of HBV vaccine were eligible, provided they were seronegative (HBs antigen negative). Immunization status for hepatitis B was assessed by studying the immunization cards of the child as well as absence of anti-HBs antibodies. We had noticed that the immunization records of some of these children were incomplete due to reasons like relocation/ migration, or where the parents had succumbed to HIV. Hence, relying solely on immunization records and history, did not seem a robust method.

Although, hepatitis B vaccination had been introduced in several Indian states almost a decade ago, the coverage of hepatitis B vaccine was reported low with huge gaps in coverage of DPT3 and HBV3 persisting [2]. A survey from India [3], reported that in 2015-16, 45% of the children aged 12-59 months were not fully vaccinated against hepatitis B, and 20% children had not received even a single dose of hepatitis B vaccine. Some of the participants in our study had been born in remote rural areas and had later migrated to Delhi, and therefore had not received hepatitis B vaccine. Some of these children had also not received other vaccines; the missing vaccination doses were administered by us during their visits to the anti-retroviral clinic.

The disparity in ages of participants in both groups despite block randomization may have been due to the small sample size and because we did not perform stratified randomization [4]. We excluded 20 children out of 70 eligible children. The CONSORT diagram depicts that 20 children were excluded and also elucidates the reasons for exclusion [1].

We agree that the research question addressed remains unanswered. Finding even 50 children who had never received any dose of hepatitis B vaccine was very challenging for us, and hence a convenience sampling was done. This question may be answered by pooling similar data from other studies and performing a meta-analysis.

1. Jain P, Dewan P, Gomber S, et al. Three vs four dose schedule of double strength recombinant hepatitis-B vaccine in HIV-infected children: A randomized controlled trial. Indian Pediatr. 2021;58:224-28.

2. Lahariya C, Subramanya BP, Sosler S. An assessment of hepatitis B vaccine introduction in India: Lessons for roll out and scale up of new vaccines in immunization programs. Indian J Public Health. 2013;57:8-14.

3. Khan J, Shil A, Mohanty SK. Hepatitis B vaccination coverage across India: Exploring the spatial heterogeneity and contextual determinants. BMC Public Health. 20192;19:1263.

4. Broglio K. Randomization in clinical trials: Permuted blocks and stratification. JAMA. 2018;319:2223-224.