Influenza Other Respir Viruses . Incidence rates of influenza illness during pregnancy in Suzhou, China, 2015-2018

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Influenza Other Respir Viruses


. 2021 Jul 29.
doi: 10.1111/irv.12888. Online ahead of print.
Incidence rates of influenza illness during pregnancy in Suzhou, China, 2015-2018


Liling Chen ¹ , Suizan Zhou ² , Lin Bao ¹ , Alexander J Millman ² , Zhongwei Zhang ³ , Yan Wang ⁴ , Yayun Tan ¹ , Ying Song ² , Pengwei Cui ¹ , Yuanyuan Pang ¹ , Cheng Liu ¹ , Jiangchun Qin ¹ , Ping Zhang ¹ , Mark G Thompson ² , A Danielle Iuliano ² , Ran Zhang ² , Carolyn M Greene ² , Jun Zhang ¹



Affiliations

• PMID: 34323381
• DOI: 10.1111/irv.12888

Free article

Abstract

Background: Data on influenza incidence during pregnancy in China are limited.
Methods: From October 2015 to September 2018, we conducted active surveillance for acute respiratory illness (ARI) among women during pregnancy. Nurses conducted twice weekly phone and text message follow-up upon enrollment until delivery to identify new episodes of ARI. Nasal and throat swabs were collected ≤10 days from illness onset to detect influenza.
Results: In total, we enrolled 18 724 pregnant women median aged 28 years old, 37% in first trimester, 48% in second trimester, and 15% in third trimester, with seven self-reported influenza vaccination during pregnancy. In the 18-week epidemic period during October 2015 to September 2016, influenza incidence was 0.7/100 person-months (95% CI: 0.5-0.9). In the cumulative 29-week-long epidemic during October 2016 to September 2017, influenza incidence was 1.0/100 person-months (95% CI: 0.8-1.2). In the 11-week epidemic period during October 2017 to September 2018, influenza incidence was 2.1/100 person-months (95% CI: 1.9-2.4). Influenza incidence was similar by trimester. More than half of the total influenza illnesses had no elevated temperature and cough. Most influenza-associated ARIs were mild, and <5.1% required hospitalization.
Conclusions: Influenza illness in all trimesters of pregnancy was common. These data may help inform decisions regarding the use of influenza vaccine to prevent influenza during pregnancy.

Keywords: active surveillance; cohort; incidence rate; influenza; pregnant women.