Defining RSV epidemic season in southwest China and assessing the relationship between birth month and RSV infection: A 10-year retrospective study from June 2009 to May 2019

Taoyu Li; Heping Fang; Xiangyu Liu; Yu Deng; Na Zang; Jun Xie; Xiaohong Xie; Zhengxiu Luo; Jian Luo; Yulin Liu; Zhou Fu; Luo Ren; Enmei Liu

doi:10.1002/jmv.28928

Defining RSV epidemic season in southwest China and assessing the relationship between birth month and RSV infection: A 10-year retrospective study from June 2009 to May 2019

J Med Virol. 2023 Jul;95(7):e28928. doi: 10.1002/jmv.28928.

Authors

Taoyu Li^{1

2}, Heping Fang^{1

2}, Xiangyu Liu^{1

2}, Yu Deng¹, Na Zang¹, Jun Xie¹, Xiaohong Xie¹, Zhengxiu Luo¹, Jian Luo¹, Yulin Liu¹, Zhou Fu¹, Luo Ren^{1

2}, Enmei Liu¹

Affiliations

¹ Department of Respiratory Medicine, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, Chongqing, China.
² Pediatric Research Institute, Children's Hospital of Chongqing Medical University, Chongqing, China.

PMID: 37455559
DOI: 10.1002/jmv.28928

Abstract

Respiratory syncytial virus (RSV) is one of the most common causes of lower respiratory tract infections (LRTI). However, only limited information is available regarding its seasonality and its relationship with birth month. A retrospective hospital-based study was carried out from June 2009 to May 2019 in Chongqing, southwest of China. LRTI cases under 5 years were enrolled in this study and PCR was used to detect 8 respiratory viruses. RSV seasonality was determined using "average annual percentage" (AAP) and "percent positivity" method. A total of 6991 cases were enrolled in this study, with an RSV positivity of 34.5%. From June 2009 to May 2019, we analyzed RSV epidemic season during 10 RSV epidemic years in Chongqing using two methods. The result of AAP method was similar to that of percent positivity method with a 30% threshold, which showed an epidemic season of roughly October to March in the subsequent year, with a small peak in June. On average, the RSV epidemic season in RSV-A dominant years typically started earlier (week 42 for RSV-A vs. week 46 for RSV-B), ended earlier (week 12 for RSV-A vs. week 14 for RSV-B), lasted longer (24 weeks for RSV-A vs. 22 weeks for RSV-B), and reached its peak earlier (week 2 for RSV-A vs. week 3 for RSV-B) than in RSV-B dominant years. The proportion of severe LRTI was higher in cases of single infection with RSV-A compared to those of single infection with RSV-B (26.3% vs. 22.3%, p = 0.024). Among infants under 1 year, those born in May and August through December were more likely to be infected with RSV. Infants born 1-2 months before the epidemic season were relatively more susceptible to RSV infection. In Chongqing, the RSV epidemic was seasonal and usually lasted from October to March of next year with a small peak in summer. Infants born 1-2 months before the epidemic season were relatively more susceptible to RSV infection and this population should be targeted while developing RSV immunization strategies.

Keywords: infant; respiratory syncytial virus; respiratory tract infections; season.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Child, Preschool
China / epidemiology
Epidemics
Female
Humans
Infant
Male
Respiratory Syncytial Virus Infections* / epidemiology
Respiratory Syncytial Virus, Human
Respiratory Tract Infections* / epidemiology
Respiratory Tract Infections* / virology
Retrospective Studies
Seasons*