Background and Aims: In late November 2015 and early February 2016, an outbreak of
H1N1 influenza A virus infection occurred in the north of Iran. The aim of this study was to describe
the incidence of mortality due to H1N1 influenza among patients admitted in hospitals affiliated to Mazandaran
University of Medical Sciences in north of Iran.
Material and Methods: A descriptive cross-sectional study was done using the medical records of mortality
cases of influenza A, whose result of RT-PCR (reverse transcriptase polymerase chain reaction assay)
confirmed H1N1. Demographic data, symptoms and signs of disease, clinical backgrounds, radiographic
evidences, laboratory findings, treatment procedure and outcome of these patients were recorded.
Results: Out of the 428 confirmed cases of influenza A (H1N1) in Mazandaran province between 21st
March 2015 and 19th March 2016, 23 (5.3%) deaths (10 males and 13 females) were reported. Death occurred
between outbreak in late November 2015 and early February 2016. The average age of deceased
patients was 46.9±21.4 years old (range 14-95 years). The most prevalent symptoms and signs were: fever
(91.3%), cough (82.6%), dyspnea (73.9%), and headache (69.5%). The most underlying conditions among
decedent patients were: heart failure (47.8%), diabetes mellitus (30.4%), and BMI≥40 (30.4%).
Conclusion: The association between underlying risk factors and mortality rate, emphasizes the priority
of vaccination in high risk groups.