Reduction of influenza A(H3N2)-associated symptoms by influenza vaccination in school aged-children during the 2014-2015 winter season dominated by mismatched H3N2 viruses

ABSTRACT

Background: Little is known about the vaccine effectiveness (VE) in attenuating the influenza-associated symptoms in children during the 2014–2015 influenza season in Beijing, China, in which there was a mismatch between the vaccine and circulating strain.

Methods: This study included 210 laboratory-confirmed influenza cases among children, who were enrolled in 2014, from November 1 to December 31. Standard demographic information and clinical symptoms were recorded. Influenza vaccination was confirmed via a vaccination registry. Univariate and multivariate analyses were used to estimate the odds of presenting with clinical symptoms among vaccinated and unvaccinated groups, adjusting for sex, age, area, BMI level, and chronic conditions.

Results: Among the 210 laboratory-confirmed influenza cases, 170 (81.0%) presented with fever ≥38°C. The other most common symptoms were cough (78.1%), sore throat (46.7%), nasal congestion/rhinorrhea (38.6%), headache (34.8%), fatigue (24.8%) and myalgia/arthralgia (16.2%). Approximately 9.0% (19/210) exhibited nausea/vomiting, and 2.4% (5/210) exhibited diarrhea/abdominal pain. Respiratory complications occurred in 5.7% (12/210) of the confirmed influenza cases. In 210 laboratory-confirmed cases, univariate and multivariate conducted after adjusted for the aforementioned characteristics suggested that the odds of fever ≥ 38°C were significantly reduced in vaccinated children (odds ratio [OR]: 0.42, 95% CI: 0.19–0.93; P = 0.033).

Conclusions: Influenza vaccination may reduce the clinical symptoms of laboratory-confirmed influenza cases potentially even in the mismatching season.

KEYWORDS:

• Influenza
• vaccination
• symptoms
• outbreak
• school
• children

Acknowledgments

We thank all the 70 schools participated in this study, and we also appreciate all of the support of the data collectors. Also, we thank the children and their parents, all health workers and teachers involved in this study for their sustained support.

Disclosure of potential conflicts of interest

No potential conflict of interest was reported by the authors.

Author’s contribution

This study was conceived by Wei Duan and Peng Yang. Wei Duan, Li Zhang and Shuangsheng Wu collected study data and Wei Duan also interpreted the data. All the co-authors in this study performed the study.

Additional information

Funding

This work was supported by Beijing Health System High Level Health Technology Talent Cultivation Plan (2013-3-098), Beijing Municipal Science and Technology Commission (D141100003114002), Capital’s Funds for Health Improvement and Research (2018-2-1013), Beijing Talents Fund (2014000021223ZK36).