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. 2014 Oct;20(10):1723-6.
doi: 10.3201/eid2010.140431.

Differences in influenza seasonality by latitude, northern India

Parvaiz A Koul, Shobha Broor, Siddhartha Saha, John Barnes, Catherine Smith, Michael Shaw, Mandeep Chadha, Renu B Lal

Differences in influenza seasonality by latitude, northern India

Parvaiz A Koul et al. Emerg Infect Dis. 2014 Oct.

Abstract

The seasonality of influenza in the tropics complicates vaccination timing. We investigated influenza seasonality in northern India and found influenza positivity peaked in Srinagar (34.09°N) in January-March but peaked in New Delhi (28.66°N) in July-September. Srinagar should consider influenza vaccination in October-November, but New Delhi should vaccinate in May-June.

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Figures

Figure 1
Figure 1
Weekly trends and proportion of annual numbers of positive influenza cases, by epidemiologic week and influenza type, Srinagar (A) and New Delhi (B), India, 2011–2012. Clear seasonal peaks are seen in January–March (weeks 1–16) for Srinagar and in July and September (weeks 28–40) for New Delhi.
Figure 2
Figure 2
Comparison of latitudes of Srinagar and New Delhi, India, and distribution of influenza virus infections, 2011–2012. A) Locations of Srinagar and New Delhi (black triangles), with vertical lines indicating 30°N latitude and equator. B) Monthly distribution of cases of influenza virus infection in Srinagar (34.0°N latitude). C) Monthly distribution of cases of influenza virus infection in New Delhi (28.7°N latitude). Arrows indicate proposed vaccination timing; latitude of each city is shown. Map created in Epi-Map in Epi Info 7 (Centers for Disease Control and Prevention, Atlanta, GA, USA).
See this image and copyright information in PMC

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