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Bijukchhe SM, Gurung M, Pokhrel B, Shakya M, Pant D, Maskey P, Maskey H, Dhakal B, Rajkarkinar S, Bista S, Voysey M, Mujadidi YF, Kim YC, Atherton R, Jones E, Mclean F, Shrestha S, Hill M, Nyland KT, Kelly S, O'reilly P, Sah GP, Basnyat B, Pollard AJ, Shrestha S. Immune responses to typhoid conjugate vaccine in a two dose schedule among Nepalese children <2 years of age. Vaccine 2024; 42:2018-2025. [PMID: 38395723 DOI: 10.1016/j.vaccine.2024.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 01/29/2024] [Accepted: 02/02/2024] [Indexed: 02/25/2024]
Abstract
BACKGROUND Previously, the Vi-typhoid conjugate vaccine (Vi-TT) was found to be highly efficacious in Nepalese children under 16 years of age. We assessed the immunogenicity of Vi-TT at 9 and 12 months of age and response to a booster dose at 15 months of age. METHODS Infants were recruited at Patan Hospital, Kathmandu and received an initial dose of Vi-TT at 9 or 12 months of age with a booster dose at 15 months of age. Blood was taken at four timepoints, and antibody titres were measured using a commercial ELISA kit. The primary study outcome was seroconversion (4-fold rise in antibody titre) of IgG one month after both the doses. FINDINGS Fifty children were recruited to each study group.Some visits were disrupted by the COVID19 pandemic and occurred out of protocol windows.Both the study groups attained 100 % IgG seroconversion after the initial dose. IgG seroconversion in the 9-month group was significantly higher than in the 12-month group (68.42 % vs 25.8 %, p < 0.001). Among individuals who attended visits per protocol, IgG seroconversion after the first dose occurred in 100 % of individuals (n = 27/27 in 9-month and n = 32/32 in 12-month group). However, seroconversion rates after the second dose were 80 % in the 9-month and 0 % in the shorter dose-interval 12-month group (p < 0.001) (n = 16/20 and n = 0/8, respectively). INTERPRETATION Vi-TT is highly immunogenic at both 9 and 12 months of age. Stronger response to a booster in the 9-month group is likely due to the longer interval between doses.
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Affiliation(s)
- Sanjeev M Bijukchhe
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal; Department of Paediatrics, University of Oxford, Oxford, United Kingdom.
| | - Meeru Gurung
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Bhishma Pokhrel
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Mila Shakya
- Oxford University Clinical Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Dikshya Pant
- Oxford University Clinical Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Pratistha Maskey
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Himang Maskey
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Babita Dhakal
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Shristy Rajkarkinar
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Sabitri Bista
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Merryn Voysey
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Yama F Mujadidi
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Young Chan Kim
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Rachel Atherton
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Elizabeth Jones
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Florence Mclean
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Sonu Shrestha
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Matilda Hill
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | | | - Sarah Kelly
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Peter O'reilly
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Ganesh Prasad Sah
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Buddha Basnyat
- Oxford University Clinical Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Andrew J Pollard
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Shrijana Shrestha
- Deparment of Paediatrics, Patan Academy of Health Sciences, Kathmandu, Nepal
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