41 participants including flu experts and health representatives from the US-CDC, OpenHealth, the Executive committee / Foundation for Influenza Epidemiology, the University of Edinburgh, Fondation Mérieux, Sanofi Pasteur and the WHO attended the meeting.
Summary of the 2015-2016 season results
During the 2015/2016 season, the GIHSN included 29 hospitals across 9 countries (Russian Federation, Czech Republic, France, Turkey, China, India, Spain, Mexico and Brazil) in both Northern and Southern Hemisphere.
Inpatients were enrolled from October 2015 to June 2016 in the Northern hemisphere, with variations depending on the site.
The highest wave of hospital admissions started during weeks 1-2, slowly declined after week 11, with a peak of number of admissions around weeks 3 and 4, 2016.
This 2015/2016 season was dominated by influenza A(H1N1)pdm09 (60%) and B/Victoria lineage (22%) (not included in the TIV), with low but relevant circulation of A(H3N2) (10%).
The H1N1 genetic changes were detected by laboratory sites, most of them being reference laboratory of WHO.
Burden of disease
A(H1N1)pdm09 and B/Victoria lineage severe cases had a high impact among the young population, whereas A(H3N2) distribution was more homogenous across age groups.
Comorbidities and underlying conditions such as diabetes, CVD, COPD, asthma, immunodeficiency, renal disease, neuromuscular, or liver disease were related to an increased risk of influenza. Pregnancy was a clear risk factor especially when there was an interaction with comorbidities (aOR= 1.9, 95%CI: 1.2-1.9 pregnancy only; aOR=4.55, 95% CI: 1.43 – 14.49 pregnancy with comorbidity).
A(H1N1)pdm09 was related to severe disease (ICU, mechanical ventilation, in-hospital death and pneumonia).
A(H3N2) was related to respiratory and metabolic failure. B/Victoria was associated with hospital deaths and cardiovascular complications.
The pooled analysis showed a reduction of the risk of getting hospitalized for influenza by statistically significant IVE of 40% against H1N1 all ages, 20.5% against H3N2 all ages and insignificant IVE for B/Victoria lineage given the mismatch with the TIV vaccine.
Effectiveness was high in preventing A(H1N1)pdm09 related admissions in the not previously vaccinated (≈ 65%). Previous influenza vaccination altered the Immune response due to the antigenic characteristics of the circulating strains and their relatedness to the composition of the seasonal 2015/16 and previous season vaccines. It was mentioned that vaccination coverage was globally low (average 15%) and this is a pending issue for the estimation of vaccine effectiveness.
Other respiratory viruses
This annual meeting was the opportunity to present results of analysis on other respiratory viruses during three consecutive seasons, 2012/2013 to 2014/2015. Four sites contributed to the data collection (Saint Petersburg, Turkey, Valencia and Fortaleza).
Other than influenza, RSV was the most dominant respiratory virus (21%), followed by Rhinovirus/enterovirus (13%). Results showed that other respiratory viruses circulated earlier in the season than influenza. RSV is particularly prevalent among young children.
Development and perspectives
During this 4th Annual Meeting, the GIHSN showed its potential to make a substantial contribution to a better understanding of severe disease related to respiratory viruses. There is a strong commitment from the coordination office and all the implementing partners to contribute to further development and success of the network.
Eight new sites are joining the GIHSN (Canada, Peru, Romania, Kazakhstan, Ivory Coast, Tunisia, and South Africa) and will collect data during the 2016/2017 season. There will also be involvement of new partners in the coordination of the GIHSN.