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ObjectiveTo evaluate the vaccine effectiveness (VE) of inactivated trivalent influenza vaccine in primary and secondary school students. MethodsRespiratory specimens were detected with PCR for influenza virus nucleic acid among 286 primary and secondary school students (6 – 15 years old) diagnosed as influenza-like illness (ILI) cases at all fever clinics in Nanshan district of Shenzhen city during an influenza season (from November 2021 to May 2022) and the ILI cases’ information on demography and influenza vaccination were collected simultaneously. The ILI cases positive for viral nucleic acid were assigned into a case group and those negative into a control group. Influenza vaccination ratio and odds ratio [OR] of viral nucleic acid positivity for the two groups were analyzed and compared to estimate the VE of influenza vaccination. ResultsOf the 286 ILI cases, 68 (23.78%) were positive for influenza nucleic acid (all belonging to B strain) and 218 (76.22%) were negative. The ratio of seasonal influenza vaccination was 5.88% (4/64) for the cases and 15.14% (33/216) for the controls, and the OR of being virus nucleic acid positive was 0.3886 (95% confidence interval [CI]: 0.1528 – 0.9880) for the vaccinated ILI cases. The estimated VE was 61.14% (95%CI: 1.20% – 84.72%) for seasonal influenza vaccination. ConclusionSeasonal influenza vaccination can protect primary and secondary school students from influenza virus infection. The result suggests that seasonal influenza vaccination needs to be promoted among school age children.

As a simple, rapid and effective research method, test-negative design (TND) has been widely used to support the evaluation of post-marketing effectiveness of vaccines and efficacies of interventions in healthcare institutions, showing a magnificent prospect of application. With the emergence of new derivative types such as real-time TND and cluster-randomized TND, TND has also been gradually applied to the exploration of disease risk factors and effectiveness evaluation of interventions. However, there are still few related research reports in China. We introduced the basic principles, methods and essentials of implementation, newly derivative types such as real-time TND and cluster-randomized TND, advantages and limitations of TND, as well as its applications in assessing post-marketing effectiveness for vaccines and efficacies of interventions, providing a theoretical and practical basis for researchers in China to carry out relevant research.

ObjectiveTo evaluate influenza vaccine effectiveness (VE) in preventing laboratory confirmed influenza illness among children aged 6 – 59 months during 2011 – 2021, and to provide evidences for improving vaccination recommendation and policy-making. MethodsBased on a prospective influenza surveillance conducted at the Soochow University Affiliated Children′s Hospital in Suzhou city, Jiangsu province from October 2011 to May 2021, we conducted a test-negative case-control study. The participants of the study were selected from 5 554 influenza-like illness (ILI) and 7 737 severe acute respiratory infection (SARI) outpatients/inpatients aged 6 – 59 months and with nasopharyngeal swab/sputum specimen test for influenza virus nucleic acid in the surveillance and influenza vaccination records of all the ILI and SARI patients were checked retrospectively. The cases of the study were influenza virus-positive ILI (n = 517) and SARI (n = 582) patients aged 6 – 59 months; the controls were 1 : 2 age- and clinic attending/hospital admission date-matched influenza virus-negative ILI/SARI patients. The adjusted odds ratio (aOR) of vaccination and VE were estimated using conditional logistic regression. ResultsThe vaccination records were available for 73.3% (9 747) of the registered patients and the observed vaccination rate was 1.79% (174/9 747). The overall VE for all the ILI/SARI patients was 36.8% (95% confidence interval [95% CI]: – 4.7% – 61.9%); the VE was 26.7% (95% CI: – 34.8% – 60.2%) for the ILI and 53.1% (95% CI: – 17.0% – 81.2%) for the SARI. The VE were 28.9% (95% CI: – 31.2% – 61.5%) and 51.2% (95% CI: – 21.3% – 80.4%) for the patients aged 6 – 35 months and 36 – 59 months. The VE of partial vaccination and full vaccination for children aged 6 – 35 months were 21.6% (95% CI = – 65.1% – 62.7%) and 40.6% (95% CI = – 66.0% – 78.8%), respectively. ConclusionThe overall VE of influenza vaccination was 36.8% among 6 – 59 months old children, with a higher VE against SARI than that against ILI and a higher VE among the children aged 36 – 59 months than that among those aged 6 – 35 months. Full dose influenza vaccination provided better protection than partial dose vaccination for children aged 6 – 35 months.