After the H1N1 virus mutation last year, experts had confirmed that the disease was not seasonal anymore.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/swine-flus-tendency-mutate-leads-rise-cases
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/daily-news-analysis-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/swine-flu
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/influenza
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/infectious-diseases
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/animal-diseases
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/indian-council-medical-research-icmr
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/health