Clinical Scorecard: Impact of Annual Influenza Vaccination on Immune Response in a Hong Kong Community Cohort During 2021/22 and 2022/23
At a Glance
Category
Detail
Condition
Seasonal influenza infection prevention
Key Mechanisms
Repeated annual influenza vaccination influences antibody titer boosting and waning, assessed by hemagglutination inhibition assays
Target Population
Community-dwelling individuals in Hong Kong aged ≥18 years receiving annual influenza vaccination
Care Setting
Community-based vaccination and sero-epidemiological surveillance
Key Highlights
Repeated influenza vaccination is associated with reduced antibody titer increase at 14 days post-vaccination compared to first-time vaccination.
Participants with higher vaccination uptake showed significantly slower antibody waning for certain influenza strains but reached similar antibody titers at 6 months post-vaccination.
The absence of influenza circulation during the COVID-19 pandemic allowed assessment of vaccine-induced antibody dynamics without confounding natural infection.
Guideline-Based Recommendations
Diagnosis
Use hemagglutination inhibition (HAI) assays to measure antibody titers against contemporary and prior influenza vaccine strains.
Management
Recommend annual influenza vaccination as the best protective measure against influenza despite attenuated antibody responses in repeat vaccinees.
Consider vaccination history when evaluating immune response and planning vaccination strategies.
Monitoring & Follow-up
Monitor antibody titers at multiple time points post-vaccination (e.g., day 14 and 6 months) to assess boosting and waning dynamics.
Use longitudinal serological sampling to evaluate vaccine immunogenicity in community cohorts.
Risks
Attenuated antibody responses in repeat vaccinees may be associated with reduced vaccine effectiveness in some years.
Patient & Prescribing Data
Adults aged ≥18 years in a Hong Kong community cohort receiving inactivated influenza vaccines in consecutive seasons
Repeat vaccination leads to lower mean fold rises in antibody titers shortly after vaccination but maintains comparable antibody levels at 6 months, suggesting sustained longer-term immunity despite initial attenuation.
Clinical Best Practices
Encourage annual influenza vaccination to maintain population immunity, even in the context of repeated vaccination.
Collect detailed vaccination history to interpret antibody response data accurately.
Perform serial antibody measurements to understand individual and population-level immune dynamics.
Account for the absence of natural influenza infection when evaluating vaccine immunogenicity during pandemic periods.
by Jennifer C Zhong, Shuyi Zhong, Lisa Touyon, Faith Ho, Niki Y M Au, Samuel M S Cheng, Dennis K M Ip, Malik Peiris, Emily T Martin, Sarah Cobey, Sook-San Wong, Nancy H L Leung, Benjamin J Cowling
