A two wave comparison of characteristics of hospitalized patients with severe and non-severe pandemic influenza A (H1N1) 2009 (H1N1pdm09) in Saurashtra Region, India

Abstract

Objective: The primary objective of the following study was to determine and secondarily to compare the clinical and epidemiological characteristics of hospitalized patients with severe and non-severe pandemic influenza A (H1N1) during two waves from September 2009 to January 2011. Materials and Methods: A total of 274 cases were hospitalized during the first wave from September 2009 to March 2010 and from June 2010 to February 2011, 237 cases hospitalized in different hospitals of Rajkot during the second wave. Real-time reverse-transcriptase-polymerase-chain-reaction testing was used to confirm infection. Two wave′s comparison was made for factors associated with disease severity. Results: During the first wave 87 (31.8%) patients had severe disease with mortality of 81.6% while during the second wave there were 53 (22.36%) patients having severe disease with higher mortality (94.3%) than the first wave. There were more children up to 15 years of age that required intensive care during the second wave (30.2%) compared to the first wave (20.7%). First wave reported more females and cases from an urban area. Presence of co-existing condition, especially pregnancy was a significant risk factor during the first wave, but not during the second wave. All patients have received antiviral drug oseltamivir during both waves. During the second wave, 39.6% of patients with severe cases received it within 2 days of onset of illness. This was higher than the first wave (19.5%). Conclusion: Higher mortality was reported during the second wave of pandemic influenza A (H1N1) 2009 (H1N1pdm09). There were more cases among the younger age group than adults during the second wave.

Keywords

• Disease severity waves
• epidemiologic characteristics
• influenza A (H1N1)