Factors influencing infection by pandemic influenza A(H1N1)pdm09 over three epidemic waves in Singapore

Influenza and Other Respiratory Viruses

Mark I. C. Chen¹  Alex R. Cook¹  Wei Yen Lim¹  Raymond Lin⁵  Lin Cui⁵  Ian G. Barr³  Anne Kelso³  Vincent T. Chow⁴  Yee Sin Leo¹  Jung Pu Hsu⁴  Rob Shaw³  Serene Chew²  Joe Kwan Yap²  Meng Chee Phoon⁴  Hiromi W. L. Koh¹  Huili Zheng¹  Linda Tan¹ 

[1] Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore;Institute of Infectious Diseases and Epidemiology, Tan Tock Seng Hospital, Singapore;WHO Collaborating Centre for Reference and Research on Influenza, Melbourne, Vic., Australia;Department of Microbiology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore;National Public Health Laboratory, Ministry of Health, Singapore

关键词: Epidemic waves;    H1N1pdm09;    haemagglutination inhibition;    risk factors;    seroconversion;    seroepidemiology;   

DOI  :  10.1111/irv.12129

来源: Wiley

【 摘 要 】

Abstract

Introduction

Previous influenza pandemics had second and on occasion third waves in many countries that were at times more severe than the initial pandemic waves.

Objective

This study aims to determine the seroepidemiology of successive waves of H1N1pdm09 infections in Singapore and the overall risks of infection.

Methods

We performed a cohort study amongst 838 adults, with blood samples provided upon recruitment and at 5 points from 2009 to 2011 and tested by haemagglutination inhibition (HI) with A/California/7/2009 (H1N1pdm09). Surveys on key demographic and clinical information were conducted at regular intervals, and associations between seroconversion and these variables were investigated.

Results

After the initial wave from June to September 2009, second and third waves occurred from November 2009 to February 2010 and April to June 2010, respectively. Seroconversion was 13·5% during the first wave and decreased to 6·2% and 6·8% in subsequent waves. Across the three waves, the elderly and those with higher starting HI titres were at lower risk of seroconversion, while those with larger households were at greater risk. Those with higher starting HI titres were also less likely to have an acute respiratory infection.

Conclusions

The second and third waves in Singapore had lower serological attack rates than the first wave. The elderly and those with higher HI titres had lower risk, while those in larger households had higher risk of seroconversion.

【 授权许可】

Unknown   
© 2013 John Wiley & Sons Ltd