Effectiveness of influenza vaccination on influenza-associated hospitalisations over time among children in Hong Kong: a test-negative case-control study

Publication date: Available online 12 November 2018Source: The Lancet Respiratory MedicineAuthor(s): Shuo Feng, Susan S Chiu, Eunice L Y Chan, Mike Y W Kwan, Joshua S C Wong, Chi-Wai Leung, Yiu Chung Lau, Sheena G Sullivan, J S Malik Peiris, Benjamin J CowlingSummaryBackgroundThe protection conferred by influenza vaccination is generally thought to last less than a year, necessitating annual revaccination. However, the speed with which influenza vaccine effectiveness might decline during a year is unknown, which is of particular importance for locations with year-round influenza activity. We aimed to assess how influenza vaccine effectiveness changes by time intervals between vaccination and admission to hospital, taking advantage of almost year-round circulation of influenza in Hong Kong.MethodsIn this test-negative case-control study, we analysed vaccine effectiveness in children (aged 6 months to 17 years) who were admitted to hospital in Hong Kong over 5 consecutive years (2012–17). We included those who were admitted to general wards in four public hospitals in Hong Kong with a fever (≥38°C) and any respiratory symptom, such as runny nose, cough, or sore throat. We used direct immunofluorescence assay and reverse transcription PCR to detect influenza virus infection, and recorded children's influenza immunisation history. We compared characteristics of positive cases and negative controls and examined how vaccine effectiveness changed by time between vaccination and...
Source: The Lancet Respiratory Medicine - Category: Respiratory Medicine Source Type: research