Influenza Vaccine Effectiveness against Influenza A-Associated Outpatient and Emergency-Department-Attended Influenza-like Illness during the Delayed 2022–2023 Season in Beijing, China
Li Zhang,
Guilan Lu,
Chunna Ma,
Jiaojiao Zhang,
Jia Li,
Wei Duan,
Jiaxin Ma,
Weixian Shi,
Yingying Wang,
Ying Sun,
Daitao Zhang,
Quanyi Wang,
Da Huo
Affiliations
Li Zhang
Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, No.16 He Pingli Middle St, Dongcheng District, Beijing 100013, China
Guilan Lu
Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, No.16 He Pingli Middle St, Dongcheng District, Beijing 100013, China
Chunna Ma
Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, No.16 He Pingli Middle St, Dongcheng District, Beijing 100013, China
Jiaojiao Zhang
Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, No.16 He Pingli Middle St, Dongcheng District, Beijing 100013, China
Jia Li
Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, No.16 He Pingli Middle St, Dongcheng District, Beijing 100013, China
Wei Duan
Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, No.16 He Pingli Middle St, Dongcheng District, Beijing 100013, China
Jiaxin Ma
Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, No.16 He Pingli Middle St, Dongcheng District, Beijing 100013, China
Weixian Shi
Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, No.16 He Pingli Middle St, Dongcheng District, Beijing 100013, China
Yingying Wang
Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, No.16 He Pingli Middle St, Dongcheng District, Beijing 100013, China
Ying Sun
Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, No.16 He Pingli Middle St, Dongcheng District, Beijing 100013, China
Daitao Zhang
Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, No.16 He Pingli Middle St, Dongcheng District, Beijing 100013, China
Quanyi Wang
Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, No.16 He Pingli Middle St, Dongcheng District, Beijing 100013, China
Da Huo
Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, No.16 He Pingli Middle St, Dongcheng District, Beijing 100013, China
Background: During the 2022–2023 influenza season, the influenza activities in most regions of China were postponed, including Beijing. The unusually delayed influenza epidemic posed a challenge to the effectiveness of the influenza vaccine. Methods: Using the test-negative design, we evaluated influenza vaccine effectiveness (VE) during the 2022–2023 influenza season against influenza A-associated outpatient and emergency-department-attended influenza-like illness (ILI) in Beijing, China, from 9 January to 30 April 2023. Results: The analysis included 8301 medically attended ILI patients, of which 1342 (46.2%) had influenza A(H1N1)pdm09, 1554 (53.4%) had influenza A(H3N2), and 11 (0.4%) had co-infection of the two viruses. VE against influenza A-associated ILI patients was 23.2% (95% CI: −6.5% to 44.6%) overall, and 23.1%, 9.9%, and 33.8% among children aged 6 months to 17 years, adults aged 18–59 years, and adults aged ≥60 years, respectively. VE against influenza A(H1N1)pdm09 and against influenza A(H3N2) were 36.2% (95% CI: −1.9% to 60.1%) and 9.5% (95% CI: −34.1% to 39.0%), respectively. VE of the group with vaccination intervals of 14–90 days (70.1%, 95% CI: −145.4 to 96.4) was higher than that of the groups with a vaccination interval of 90–149 days (18.7%, 95% CI: −42.4% to 53.6%) and ≥150 days (21.2%, 95% CI: −18.8% to 47.7%). Conclusions: A moderate VE against influenza A(H1N1)pdm09 and a low VE against influenza A(H3N2) were observed in Beijing during the 2022–2023 influenza season, a season characterized with a delayed and high-intensity influenza epidemic. VE appears to be better within three months after vaccination. Our findings indicate a potential need for the optimization of vaccination policies and underscore the importance of continuous monitoring of influenza to enhance vaccines and optimizing vaccination timing.
