Comparison of 1 Versus 2 Doses of Quadrivalent Influenza Vaccine in 3-8-Year-Old Children with Different Immunological States - Jiangsu Province, China, 2021.

What is already known about this topic?:The quadrivalent influenza vaccine (QIV) provides protection against a broader range of influenza strains by including strains of influenza A/H1N1, A/H3N2, B/Yamagata, and B/Victoria. What is added by this report?:This study aimed to assess the immunogenicity and safety of administering a single dose compared to two doses of QIV in children, taking into consideration their previous influenza vaccination history. What are the implications for public health practice?:This study provides evidence supporting the use of a single dose of the QIV in children aged 3-8 years who have previously received two or more doses of influenza vaccine. However, children who have not been previously vaccinated with influenza vaccine should still adhere to the recommended schedule of receiving two doses.