A study that assessed the burden of influenza hospitalisations found thatroughly five people in every 1,000 in the community under study required such hospitalisation. It was the first such assessment in India,the researchers say.
Carried out by Punes National Institute of Virology,it found 20 per cent of hospitalised patients had influenza,adjusted that finding with those from health utilisation surveys of a rural population in Pune district,and then estimated what proportion of the local community required hospitalisation for influenza. The NIV study was published in the journal PloS One on May 15.
The study from May 2009 to April 2011 was undertaken on patients at King Edward Memorials 35-bed rural hospital at Vadu,30 km from Pune,a five-bed primary health centre,and 28 private nursing homes. It enrolled 3,391 patients (out of 9,426) and 665 tested positive for influenza.
Researchers then went on to calculate the annual incidence of influenza hospitalisations at 46.8 per 10,000 during the H1N1 pandemic period,and 40.5 per 10,000 during the post-pandemic period. The average annualised incidence of influenza-associated hospitalisations was 44.1 per 10,000,which is substantially higher than the 3.6 to 11.5 per 10,000 in the United States.
During peak periods,especially in the monsoons,20 per cent of all hospital admissions in the community had influenza positivity. These findings can help health authorities inform development of influenza prevention and control strategies in India, says Dr M S Chadda,deputy director of NIV.
Our data highlights the impact of the 2009 H1N1 pandemic and seasonal influenza and provides the first estimates of influenza-associated hospitalization rates in India, she says. In our population,46 to 57 per cent of the burden of influenza-associated hospitalizations was accounted for by the swine flu influenza virus along with seasonal influenza.
In India,acute respiratory infections are a leading cause of morbidity and mortality,particularly in children less than five years of age in whom the incidence of hospitalised pneumonia is estimated at 0.37 episodes per child year. An estimated 43 million episodes of acute respiratory infection occur in India annually. However,data such as influenza-associated hospitalisation was so far unknown,the researchers say.
NIV undertook the burden study when a pandemic virus was emerging,hence the estimated incidence rates of influenza-associated hospitalisations are higher than what has been observed for seasonal influenza elsewhere,Chadda says.
We found the lowest hospitalisation incidences in persons aged over 60 years,followed by infants aged less than one year, Chadda says.