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ORIGINAL RESEARCH article

Front. Med.
Sec. Infectious Diseases: Pathogenesis and Therapy
Volume 12 - 2025 | doi: 10.3389/fmed.2025.1543398
This article is part of the Research Topic SARS-CoV-2 Vaccines Beyond the Pandemic Era View all 21 articles

Safety and immunogenicity of Ad5-nCoV administered intradermally by needle-free injector in rats

Provisionally accepted
Li Chen Li Chen 1Xiaoyin Zhang Xiaoyin Zhang 2Lairun Jin Lairun Jin 1,3Lihua Hou Lihua Hou 4Fengcai Zhu Fengcai Zhu 3*Jingxin Li Jingxin Li 3*
  • 1 School of Public Health, Southeast University, Nanjing, Jiangsu Province, China, Nanjing, Chile
  • 2 Taizhou Disease Prevention and Control Center, Taizhou, Zhejiang Province, China
  • 3 Jiangsu Provincial Center for Disease Control And Prevention, Nanjing, China
  • 4 Beijing Institute of Radiation Medicine, Academy of Military Medical Sciences (AMMS), Beijing, Beijing, China

The final, formatted version of the article will be published soon.

    Objectives: To evaluate the safety and immunogenicity of adenovirus type 5 vectored COVID-19 vaccine (Ad5-nCoV), by intradermal immunization with a needle-free injector in rats. Methods: This study was divided into two parts. In study A, 105 rats were randomly assigned to seven groups, to receive the low-dose, medium-dose, or high-dose vaccine by needle-free intradermal injections (NFI), or needle-based intramuscular injections (NI), or needle-free intradermal injections with saline solution as a control group. Blood samples were collected on day 0 before vaccination, and day 7, day 14, day 21 and day 28 after vaccination. Binding antibody, pseudovirus neutralizing antibody as well as cellular immune response were measured. The safety endpoints included weight changes and skin reactions. In study B, 32 rats were randomly assigned to four groups to receive low-dose, or medium-dose vaccine by NFI or NI, to observe pathological changes at the injection site following immunization. Results: No safety concern was noted associated with NFI of Ad5-nCoV. Comparable levels of neutralizing antibodies against various variants induced by NFI compared to NI at the same dosage. Conclusion: The NFI immunization would be considered as an alternative immunization method to replace the traditional NI for the Ad5-nCoV.

    Keywords: COVID-191, Adenovirus type-5 vector-based COVID-19 vaccine2, immunogenicity3, Safety4, Needle-free injector5

    Received: 11 Dec 2024; Accepted: 04 Feb 2025.

    Copyright: © 2025 Chen, Zhang, Jin, Hou, Zhu and Li. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Fengcai Zhu, Jiangsu Provincial Center for Disease Control And Prevention, Nanjing, China
    Jingxin Li, Jiangsu Provincial Center for Disease Control And Prevention, Nanjing, China

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.