Burden of the 1999-2008 seasonal influenza epidemics in Italy: Comparison with the H1N1v (A/California/07/09) pandemic

Abstract

Despite preventive efforts, seasonal influenza epidemics are responsible for substantial morbidity and mortality every year worldwide, including developed countries. The A/H1N1v pandemic imposed a considerable healthcare and economic burden. In order to obtain an accurate estimate of the economic burden of influenza, and hence to guide policymakers effectively, systematic studies are necessary. To this end, data from epidemiological surveillance are essential. To estimate the impact of the 1999-2008 seasonal influenza epidemics and the H1N1v pandemic, we analyzed data from the Italian Influenza Surveillance System (CIRI NET). In the period 1999-2008, the Italian surveillance network consisted of sentinel general practitioners and pediatricians, who reported cases of Influenza-Like Illness (ILI) and Acute Respiratory Infections (ARI ) observed during their clinical practice from mid-October to late April each year; reports were sent to the Center for Research on Influenza and other Viral Infections (CIRI -IV). CIRI -IV receives data from 9 of the 20 Italian regions: Liguria, Abruzzo, Calabria, Friuli Venezia Giulia, Lombardy, Puglia, Sicily, Tuscany and Umbria. Previous estimates of influenza case costs were used in economic evaluations. Clinical-epidemiological and virological surveillance of the seasonal epidemics from 1999-2008 showed that the highest epidemic period was 2004-2005, when a new variant of the H3N2 influenza virus subtype emerged (A/California/07/04). Indeed, the highest peak of morbidity in the decade occurred in February 2005 (12.6 per 1,000 inhabitants). In 1999-2008, H1N1 subtype strains circulated and co-circulated with strains belonging to the H3N2 subtype and B type. Regarding B viruses in 2001-02, viruses belonged to the B/Victoria/02/07 lineage re-emerged, and in subsequent years co-circulated with viruses belonging to the B/Yamagata/lineage. The estimated costs of seasonal epidemics from 1999-2008 in Italy ranged from €15 to €20 billion, and the costs of the H1N1v pandemic ranged from €1.3 to €2.3 billion. This Italian study yields interesting conclusions: the results of influenza surveillance in several developed countries vary markedly; influenza imposes a considerable social, healthcare and economic burden; most cases that occurred during the pandemic involved subjects under 14 years of age and, although the clinical course of H1N1v influenza was usually mild, the related economic burden was heavy.

Disease burden of 2013-2014 seasonal influenza in adults in Korea

“…In a study preformed in England, 779,000–1,164,000 general practice consultations, 19,000–31,200 hospital admissions, and 18,500–24,800 deaths annually were estimated to be attributable to influenza virus infections [18]. In the study performed in Italy, the estimated costs of seasonal epidemics from 1999–2008 in Italy ranged from EUR €15 to EUR €20 billion [19]. Differences in research methods, population and health care system including medical insurance system may have caused the difference of seasonal influenza disease burden.…”

Heterogeneous estimates of influenza virus types A and B in the elderly: Results of a meta‐regression analysis

“…For instance, a meta‐regression analysis by Jayasundara et al has shown that the natural attack rate is about four times higher (15.2% vs 3.5%) in children than in adults. Our previous research documented that, in ten consecutive seasons, children aged 0‐14 years had the highest cumulative incidence of influenza‐like illness (ILI), followed by 15‐ to 64‐year‐olds, while the lowest cumulative incidence was constantly reported in the elderly. On the other hand, despite the lower incidence rates, influenza‐attributable hospitalizations and mortality are highest among the elderly; on average, about 90% of influenza‐related deaths occur in people aged 65 years or older …”

Do the omeprazole family compounds exert a protective effect against influenza-like illness?

“…In the United States, more than 200,000 hospitalizations per year for respiratory and heart conditions have been attributed to seasonal influenza [2]. In Italy, considering seasonal epidemic periods alone, it has been estimated that 25 million cases of Influenza-like Illness (ILI) occurred from 1999 to 2008, with an average of 2.5 million cases per year [3]. …”