Abstract

Background: Despite widely available annual immunisation and antiviral therapy, seasonal influenza continues to cause considerable morbidity and mortality. Limited data are available regarding the demographic and virologic characteristics of seasonal influenza in Qatar. The aim of this study was to assess the incidence and clinical impact of laboratory-confirmed influenza infection in Qatar during the years 2016 to 2018.

Methods: Qatar Influenza Surveillance Programme involves offering laboratory testing for all individuals who present with an influenza like illness (ILI) to any primary health centre or hospital department. Upper respiratory samples are submitted to the National Virology Laboratory based at Hamad Medical Corporation, Doha, where they are tested using RT-PCR (Xpert Flu, Cepheid, Sunnyvale, California) and multiplex PCR (FTD Respiratory pathogens 21, Fast-Track Diagnostics, Esch-sur-Alzette, Luxembourg). Surveillance results, hospital admissions and mortality data were retrieved retrospectively from electronic databases. All samples tested between January 2016 and December 2018 were included. Stata (StataCorp LLC, College Station, Texas) was used for descriptive statistics. Incidence rates (IR) are reported by 100,000 population. Population data are based on those reported by Qatar Planning and Statistics Authority. The study was approved by the Institutional Review Board at Hamad Medical Corporation.

Results: Over the study period, Influenza Virus was detected in 19,339 (1.3%) out of 1,447,636 specimens from individuals with ILI, corresponding to an overall IR of 244 per 100,000 population. Of those with confirmed Influenza, there were significantly more males (56% versus 46% females, P < 0.001) and younger age groups (35% from those aged 0 to 4 years and 19% from 5 to 14 years age group). Influenza A (71.0%) predominated, nearly half (48.7%) of which were H1N1pd09 type. Significantly more cases were diagnosed during the months of October to December compared with January to March (63.0% versus 18.0%, P < 0.001) (Figure 1). During the year 2018, there were 410 Hospitalizations due to influenza, with a rate of 15.33 (95%CI 13.88; 16.88) per 100,000 hospital admissions due to Influenza and 10 deaths with an in-hospital mortality rate of 0.37 (95%CI 0.22; 0.49) per 100,000.

Conclusion: The incidence of laboratory-confirmed seasonal Influenza is high in Qatar. However, children and young adults are most commonly affected, and hence relatively low rates of severe complications and mortality are observed.

Keywords:Influenza Virus Infection; Qatar; Influenza Like Illness (ILI)

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