Seasonal Influenza Incidence in India: A Retrospective Study Based on Multiple Indian Hospital and Diagnostic Laboratory Centre

The objective of the study is to understand the seasonal variation in influenza incidence across multiple Indian states by using diagnostic laboratories data of influenza.

Materials and Methods: Diagnostic laboratory-based data of subjects who were tested for influenza between 1st January April 2014 to December 2017 across seven Indian states were analysed. In diagnostic laboratories of Maharashtra, Delhi, Uttar Pradesh, Haryana, and Rajasthan RT-PCR was used for detection of H1N1 and laboratories of Tamil Nadu used GeneXpert along with RT-PCR. A total sample size of 10,755 was used in the descriptive observational retrospective study.

Results: In case of H1N1, sample population had almost equal male and female proportion (5172) with 36.5 years mean age. In majority of states, >3-5 years age group had the highest positivity rate. Paediatric age group (0-18 years) contributed 25% of total H1N1 burden, while older adults (>60 years) contributed 15% of the total sample. The yearly trends showed a higher incidence rate of H1N1 in 2015, followed by a decline during 2016 and a surge in 2017. Monthly trends showed consistent rise in H1N1 positivity rate during early months (January, February, and March) of 2015, 2016 and 2017. For influenza B, paediatric age group (0-18 years) showed the highest positivity rate and contributed almost 40% of total influenza ‘B’ burden.

Conclusion: This study highlights the importance of big data-based analytics and its use in understanding the epidemiological behaviour of diseases like influenza. Insight by leveraging laboratories data, like in the case of current research study, gives demographic patterns of influenza in terms of age, gender, seasons, and regions/states.