Predominance of influenza A(H3N2) and Victoria lineage of influenza B in patients with influenza-like illness: A laboratory-based surveillance study from Rajasthan, India
Shiv Prakash Sharma, Neha SharmaABSTRACT
Background:
The relative prevalence of specific influenza subtypes and lineages significantly impacts seasonal epidemiology and the effectiveness of vaccines. Detailed virological data from regional centres in India are crucial, yet often limited.
Aims:
The objective is to determine the subtype and lineage-specific distribution of influenza viruses and analyse their distinct temporal patterns and clinical correlations.
Methods:
A detailed analysis was conducted on 598 influenza-positive samples identified through prospective surveillance of 7,231 patients with influenza-like illness (July 2019–June 2020). Subtyping for A(H1N1) pdm09 and A(H3N2) and lineage determination for B/Victoria and B/Yamagata were performed using real-time RT-PCR. Statistical comparisons were performed using Chi-square tests.
Results:
Influenza A accounted for 83.6% (500/598) of all positive results. Among these,A(H3N2) was overwhelmingly predominant (379/500, 75.8%;
Conclusion:
The complex co-circulation of influenza viruses in North India, with a significant predominance of A(H3N2) and exclusive circulation of B/Victoria. The clear temporal separation and age-specific differences highlight the importance of subtype-specific surveillance for informing regional vaccination strategies and preparedness for waves of illness caused by different viruses.