Sinilaite Angela, Doyon-Plourde Pamela, Young Kelsey, Harrison Robyn
NACI Secretariat, Public Health Agency of Canada.
NACI Influenza Working Group Chair at the time of the NACI Statement writing.
Can Commun Dis Rep. 2023 Apr 1;49(4):90-98. doi: 10.14745/ccdr.v49i04a01.
At the commencement of a pandemic, it is important to consider the impact of respiratory infections on the health system and the possibility of vaccine shortages due to increased demand. In the event of an influenza vaccine shortage, a strategy for administration of fractional influenza vaccine doses might be considered. This article reviews the available evidence for efficacy, effectiveness, immunogenicity and safety of fractional influenza vaccine dosing, and summarizes the National Advisory Committee on Immunization (NACI) recommendations on fractional dosing strategies by public health programs in Canada.
Two rapid literature reviews were undertaken to evaluate the efficacy, effectiveness, immunogenicity and safety of fractional influenza vaccine dosing via the intramuscular or intradermal route. The NACI evidence-based process was used to assess the quality of eligible studies, summarize and analyze the findings, and apply an ethics, equity, feasibility and acceptability lens to develop recommendations.
There was limited evidence for the effectiveness of fractional influenza vaccine dosing. Fractional dosing studies were primarily conducted in healthy individuals, mainly young children and infants, with no underlying chronic conditions. There was fair evidence for immunogenicity and safety. Feasibility issues were identified with intradermal use in particular.
NACI recommended that, in the event of a significant population-level shortage of influenza vaccine, a full-dose influenza vaccine should continue to be used, and existing vaccine supply should be prioritized for those considered to be at high risk or capable of transmitting to those at high risk of influenza-related complications or hospitalizations. NACI recommended against the use of fractional doses of influenza vaccine in any population.
在大流行开始时，重要的是要考虑呼吸道感染对卫生系统的影响以及因需求增加导致疫苗短缺的可能性。如果出现流感疫苗短缺，可考虑采用分剂量接种流感疫苗的策略。本文回顾了关于分剂量流感疫苗接种的有效性、效果、免疫原性和安全性的现有证据，并总结了加拿大国家免疫咨询委员会（NACI）关于加拿大公共卫生项目分剂量接种策略的建议。
进行了两项快速文献综述，以评估通过肌肉注射或皮内注射途径分剂量接种流感疫苗的有效性、效果、免疫原性和安全性。采用NACI基于证据的流程来评估符合条件的研究的质量，总结和分析研究结果，并从伦理道德、公平性、可行性和可接受性的角度提出建议。
分剂量接种流感疫苗有效性的证据有限。分剂量接种研究主要在健康个体中进行，主要是幼儿和婴儿，无潜在慢性病。免疫原性和安全性有合理证据。特别是皮内使用时发现了可行性问题。
NACI建议，如果出现大规模人群层面的流感疫苗短缺，应继续使用全剂量流感疫苗，现有疫苗供应应优先用于那些被认为处于高风险或可能将流感传播给有流感相关并发症或住院高风险人群的人。NACI建议任何人群都不要使用分剂量流感疫苗。
