Molecular Detection of Influenza A and B Viruses in Four Consecutive Influenza Seasons 2015–16 to 2018–19 in a Tertiary Center in Western Saudi Arabia

Abdulhakeem Althaqafi,Abdulhakeem Althaqafi,Abdulhakeem Althaqafi,Fayssal Farahat,Fayssal Farahat,Fayssal Farahat,Asim Alsaedi,Asim Alsaedi,Asim Alsaedi,Majid Alshamrani,Majid Alshamrani,Majid Alshamrani,Moneerah S Alsaeed,Moneerah S Alsaeed,Baraa Alhajhussein,Baraa Alhajhussein,Sherif A El-Kafrawy,Sherif A El-Kafrawy,Esam I Azhar,Esam I Azhar

doi:10.2991/jegh.k.210427.001

Abstract

IntroductionInfluenza infection poses a significant public health threat. The core for disease prevention and control relies on strengthened surveillance activities, particularly in Saudi Arabia, the country that hosts the largest annual mass gathering event worldwide. This study aimed to assess the molecular and seasonal pattern of influenza virus subtypes in western Saudi Arabia to inform policy decisions on influenza vaccine.MethodsThis cross-sectional study was conducted at King Abdulaziz Medical City, western Saudi Arabia. Medical records and surveillance database of laboratory-confirmed influenza cases were reviewed from October 2015 to 2019. A panel of real-time polymerase chain reactions was performed to detect influenza A and B. Extracted RNA from a subset of positive samples was used to determine influenza A subtypes and influenza B lineages.ResultsThis study included a total of 1928 patients with laboratory-confirmed influenza infections. Influenza peaks were observed in October each season, with variant predominant strains. Influenza virus subtypes co-circulate with no reports of co-infection. Influenza A(H3N2) was reported in 42% of the cases, then influenza B (30.7%) and influenza A(H1N1)pdm09 (27.3%). Healthcare workers represented 9.4% of the cases. One-third of the cases (30.4%) were admitted to the hospital with a median admission duration of 4 days. The influenza B viruses were subtyped in 218 cases. Victoria lineage was predominant (64.1%) in 2015 and 2016; however, Yamagata was predominant in the next two consecutive seasons (94.4% and 85.4%, respectively).ConclusionThe burden due to influenza B may be underestimated with an observed vaccine mismatch. A quadrivalent influenza vaccine is recommended to reduce the health impact associated with influenza B infections. Molecular surveillance of the influenza viruses should be enhanced continuously for a better understanding of the influenza activity and assessment of vaccine effectiveness.

Highlights

Influenza infection poses a significant public health threat
This study included a total of 1928 patients with laboratoryconfirmed influenza infections over four seasons from October 2015
Throughout the studied seasons, influenza virus subtypes co-circulate with no reports of co-infection (Figure 2)

Summary

Introduction

Influenza infection poses a significant public health threat. The core for disease prevention and control relies on strengthened surveillance activities, in Saudi Arabia, the country that hosts the largest annual mass gathering event worldwide. This study aimed to assess the molecular and seasonal pattern of influenza virus subtypes in western Saudi Arabia to inform policy decisions on influenza vaccine. Influenza viruses are recognized globally as persistent threats to human health. They are the primary respiratory pathogens that cause annual epidemics with high economic loss and approximately 250,000–500,000 deaths annually worldwide [1,2]. Influenza viruses are characterized by two mechanisms that direct the evolution of new variants; antigenic drift and genetic shift [3,4]. Studies that aimed at comparing the epidemiological and clinical characteristics of influenza virus subtypes are limited and showed variant results [11,12] The antigenic drift through several mechanisms that include insertions, deletions, and substitutions are frequent among influenza A and different lineages of influenza B viruses [7,8,9,10].

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