Sleep . Changed epidemiology of narcolepsy before, during, and after the 2009 H1N1 pandemic: a nationwide narcolepsy surveillance network study in mainland China, 1990-2017

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Sleep


. 2023 Jan 3;zsac325.
doi: 10.1093/sleep/zsac325. Online ahead of print.
Changed epidemiology of narcolepsy before, during, and after the 2009 H1N1 pandemic: a nationwide narcolepsy surveillance network study in mainland China, 1990-2017


Xiling Wang ¹ , Fulong Xiao ² , Yiping Wang ¹ , Xiaowei Deng ¹ , Zhiyuan Chen ¹ , Xiaosong Dong ² , Wei Wang ¹ , Chenyang Li ² , Zhifei Xu ³ , Huijuan Wu ⁴ , Huan Yu ⁵ , Changjun Su ⁶ , Zan Wang ⁷ , Xiangdong Tang ⁸ , Yunhui Lv ⁹ , Yun Li ¹⁰ , Shuchen Sun ¹¹ , Junying Huang ¹² , Lijuan Hao ¹³ , Xuan Wei ¹⁴ , Liying Deng ¹⁵ , Yu-Shu Huang ¹⁶ , Jihui Zhang ¹⁷ , Yun-Kwok Wing ¹⁷ , Jun Zhang ¹⁸ , Emmanuel Mignot ¹⁹ , Fang Han ² , Hongjie Yu ^{20 21 22}



Affiliations

• PMID: 36595587
• DOI: 10.1093/sleep/zsac325

Abstract

Study objectives: Increased incidence of narcolepsy was reported in children during the 2009 H1N1 pandemic following Pandemrix®, a H1N1 flu vaccine. A link with A(H1N1)pdm09 infections remains controversial. Using nationwide surveillance data from China (1990 to 2017), the epidemiology of narcolepsy was analyzed.
Methods: Individual records of narcolepsy patients were collected from 15 of 42 hospitals across China known to diagnose cases. Incidence was estimated assuming representativeness of these hospitals. Age-specific incidence, epidemiological and clinical characteristics of patients were evaluated before, during, and after the 2009 H1N1 pandemic. Sensitivity analyses were conducted by including NT1 cases only and to exclude the effect of 2009 H1N1 vaccination.
Results: Average annual incidence was 0.79 per 100,000 person-years (PY) from 1990 to 2017 and 1.08 per 100,000 PY from 2003 to 2017. Incidence increased 4.17 (95%CI 4.12, 4.22) and 1.42 (95%CI 1.41, 1.44) fold during and after the 2009 H1N1 pandemic when compared to baseline. These results were robust in sensitivity analyses. Patients with onset of narcolepsy during the pandemic period were younger (notably in 5-9-year-old strata), and age shift toward younger children reversed to baseline following the pandemic.
Conclusions: Increased incidence of narcolepsy was observed during the 2009 H1N1 pandemic period. This is likely to be associated with the circulation of the wild-type A(H1N1)pdm09 virus. This observation should be considered for future influenza pandemic preparedness plans.

Keywords: 2009 H1N1 pandemic; epidemiology; narcolepsy.