Unraveling influenza sentinel surveillance in Pakistan 2008-2024: Epidemiological insights during the pre and post pandemic period of COVID-19.

BACKGROUND

The coronavirus pandemic has substantially influenced the transmission pattern of other respiratory viruses. However, screening and detecting other respiratory pathogens was unheeded during this time to combat the COVID-19 pandemic. High virulence and re assortment factors intensify the importance of influenza virus surveillance for effective disease management. Therefore, the present surveillance study was designed to determine the influenza positivity rate from 2008-24. This study will provide integral support in depicting a panoramic representation of two respiratory-pandemic periods, 2010-11 and 2019-2021, for influenza and COVID-19 pandemics, respectively.

METHODS

An inferential cross-sectional study was conducted from 2008 to 2024 by collecting influenza surveillance data from twelve sentinel sites in Pakistan. Clinical and demographic data was recorded at sample collection time. Specimens were collected through nasopharyngeal/throat swabs and stored in viral transport medium (VTM) at the sentinel site laboratory at 2-4 °C. Viral RNA was isolated from the samples using KingFisher TM Flex Purification System and MagMAX™ Viral/Pathogen Nucleic Acid Extraction Kit.

RESULTS

Within 16 years, 78118 samples were tested for influenza, of which 7999 (10.2 %) appeared positive. The positivity rate appeared very low in recent years, with only a 3.5 % positivity rate observed in 2020. Influenza A strain H1N1pdm09 seemed to be the prominent strain (n = 3407, 42.6 %), followed by influenza B (n = 2125, 26.6 %).

CONCLUSION

The positivity of influenza samples was 10.2 % and recorded in patients where typical clinical representation of influenza was absent. Fewer samples were reported during the coronavirus pandemic, which might be because influenza screening was hindered and overlooked to combat the SARS-CoV-2 virus, and the patient threshold was very high for COVID-19 virus screening.