Relationships between A(H1N1)pdm09 influenza infection and infections with other respiratory viruses

Abstract

BackgroundA(H1N1)pdm09, a new influenza pandemic virus emerged in 2009. The A(H1N1)pdm09 infection had several unique characteristics which included rapid transmissibility and high morbidity in obese individuals, pregnant women and individuals suffering from chronic diseases.ObjectivesTo study the relationships between A(H1N1)pdm09 influenza infection and infections with other respiratory viruses such as respiratory syncytial virus (RSV), human metapneumo virus (hMPV), adenovirus and seasonal influenza.MethodsSamples (nasopharyngeal swabs or aspirates) collected between 2007 until 2012 from patients of various ages that were hospitalized due to respiratory virus infections were analyzed for the presence of various respiratory viruses, using qRT-PCR.ResultsIn 2009–2010, when the pandemic influenza A(H1N1)pdm09 first appeared, two major infection peaks were noted and individuals of various ages were infected. Following the decline of the A(H1N1)pdm09 virus infection, the percentages of patients infected with adenovirus and hMPV increased, while infection frequency with RSV B and with seasonal influenza virus decreased. Furthermore, RSV infections were delayed and very few percentages of patients were co-infected with more than one virus. Interestingly, the A(H1N1)pdm09 virus lost its dominancy when it reappeared in the winter of 2010–2011, and at this time, only the incidence of RSV infections was affected by the A(H1N1)pdm09 virus.ConclusionsThe A(H1N1)pdm09 virus had distinct effects on other respiratory viruses when it first appeared versus later, when it evolved from being a pandemic to a seasonal virus.

Viral detection profile in children with severe acute respiratory infection

“…10 In Ohio, patients coinfected with rhinovirus tended to present a less severe clinical picture than those coinfected with other viruses. 7 Data from epidemiological reports in Brazil [31][32][33] and studies in other countries 3,34,35 showed that, in the post-pandemic period, H1N1 virus continues to circulate and cause SARI and deaths. The influenza virus continues to mutate and frequently re-appears in variant forms.…”

“…Respiratory infections are an important cause of morbidity and mortality throughout the world, particularly in children. [1][2][3] Besides the high susceptibility to viral respiratory infections, children present with a higher frequency of coinfections, especially those under five years of age. 4,5 The influenza A (H1N1) pandemic in 2009, affected mainly children, young adults, pregnant women, and patients with chronic diseases.…”

Surveillance of Severe Acute Respiratory Infection (SARI) for Hospitalized Patients in Northern Vietnam, 2011–2014

“…Our findings are similar to those of other reports of the viral etiologies associated with SARI from Asia and other countries (12,(17)(18)(19)(20)(21)(22). Many studies from both temperate and tropical countries have described the epidemiology and outcome of influenza A H1pdm09 associated with hospitalized SARI (12,17,(23)(24)(25)(26). Influenza infection is well-recognized as the cause of significant healthcare costs, morbidity, and mortality in temperate countries (27)(28)(29)(30)(31).…”

Seasonal Influenza A H1N1pdm09 Virus and Severe Outcomes: A Reason for Broader Vaccination in Non-Elderly, At-Risk People

“…By between 2010 and 2012, approximately 50% of the population had already developed immunity against the virus [12], and more severe cases in older and people with comorbidities were observed in the following [13]. In the 2009 pandemics, only 48% of hospitalized patients suffered from comorbidities, whereas in the 2010–2012 period, this figure had risen to 75% [14]. However, the range of comorbidities associated with severe disease has not changed significantly in recent years [15].…”

“…However, the range of comorbidities associated with severe disease has not changed significantly in recent years [15]. All these changes, and the replacement of previous seasonal influenza A(H1N1), reflect the evolution of influenza A H1N1pdm09 from a pandemic to a seasonal virus [14]. …”