Influenza epidemiology and influenza vaccine effectiveness during the 2016–2017 season in the Global Influenza Hospital Surveillance Network (GIHSN)

Abstract

Background The Global Influenza Hospital Surveillance Network (GIHSN) aims to determine the burden of severe influenza disease and Influenza Vaccine Effectiveness (IVE). This is a prospective, active surveillance and hospital-based epidemiological study to collect epidemiological data in the GIHSN. In the 2016–2017 influenza season, 15 sites in 14 countries participated in the GIHSN, although the analyses could not be performed in 2 sites. A common core protocol was used in order to make results comparable. Here we present the results of the GIHSN 2016–2017 influenza season. Methods A RT-PCR test was performed to all patients that accomplished the requirements detailed on a common core protocol. Patients admitted were included in the study after signing the informed consent, if they were residents, not institutionalised, not discharged in the previous 30 days from other hospitalisation with symptoms onset within the 7 days prior to admission. Patients 5 years old or more must also complied the Influenza-Like Illness definition. A test negative-design was implemented to perform IVE analysis. IVE was estimated using a logistic regression model, with the formula IVE = (1-aOR) × 100, where aOR is the adjusted Odds Ratio comparing cases and controls. Results Among 21,967 screened patients, 10,140 (46.16%) were included, as they accomplished the inclusion criteria, and tested, and therefore 11,827 (53.84%) patients were excluded. Around 60% of all patients included with laboratory results were recruited at 3 sites. The predominant strain was A(H3N2), detected in 63.6% of the cases (1840 patients), followed by B/Victoria, in 21.3% of the cases (618 patients). There were 2895 influenza positive patients (28.6% of the included patients). A(H1N1)pdm09 strain was mainly found in Mexico. IVE could only be performed in 6 sites separately. Overall IVE was 27.24 (95% CI 15.62–37.27. Vaccination seemed to confer better protection against influenza B and in people 2–4 years, or 85 years old or older. The aOR for hospitalized and testing positive for influenza was 3.02 (95% CI 1.59–5.76) comparing pregnant with non-pregnant women. Conclusions Vaccination prevented around 1 in 4 hospitalisations with influenza. Sparse numbers didn’t allow estimating IVE in all sites separately. Pregnancy was found a risk factor for influenza, having 3 times more risk of being admitted with influenza for pregnant women. Electronic supplementary material The online version of this article (10.1186/s12889-019-6713-5) contains supplementary material, which is available to authorized users.

High performance of rapid influenza diagnostic test and variable effectiveness of influenza vaccines in Mexico

“…Finally, our RT-PCR results showed that influenza A(H1N1) pdm09 virus was the predominant strain in our population, coinciding with other studies reporting a high circulation of this strain in Mexico during the same period (Baselga-Moreno et al, 2019), while most other Northern Hemisphere countries reported a predominance of influenza AH3N2 virus (Pebody et al 2017;Mira-Iglesias et al 2018;Wu et al 2018;Baselga-Moreno et al, 2019;Flannery et al, 2019). Interestingly, the incidence of influenza B in our study was higher than previous local seasonal averages (Cortes-Alcala et al 2018;Fernandes-Matano et al 2019), but contrasts with official national statistics showing a lower incidence of influenza B during the same period (Secretaria de Salud and Dirección General de Epidemiología, 2017).…”

“…We also evaluated the VE of 2016/17 influenza vaccines. Our overall VE estimates against any type of influenza were lower compared to the previous season (Jackson et al 2017) and almost similar to estimates from other Northern Hemisphere countries that also showed a low VE of the 2016/17 vaccines (Pebody et al 2017;Mira-Iglesias et al 2018;Wu et al 2018;Baselga-Moreno et al, 2019;Flannery et al, 2019). Our results also showed that VE against influenza AH3N2 virus was higher in children and young adults compared to older patients during the evaluated season (Kissling et al 2017;Pebody et al 2017;Wu et al 2018;Flannery et al, 2019).…”

“…Our results also showed that VE against influenza AH3N2 virus was higher in children and young adults compared to older patients during the evaluated season (Kissling et al 2017;Pebody et al 2017;Wu et al 2018;Flannery et al, 2019). Of note, VE against influenza A(H1N1)pdm09 virus was not significant in other countries that reported low circulation of this virus (Baselga-Moreno et al, 2019). Conversely, we found a significant 44.6% VE against this virus, which remains similar to previous seasons (Belongia et al 2016;Darvishian et al 2017; Table 4 Absolute numbers of influenza cases and non-cases among vaccinated and unvaccinated ILI patients.…”

Complicated hospitalization due to influenza: Results from the Global Hospital Influenza Network for the 2017–2018 season

“…During the 2017-2018 in uenza season, in uenza accounted for approximately one-third of hospital admissions with in uenza-like symptoms, which agrees with previous in uenza seasons in the GISHN, where proportions were between 21% and 31% [8][9][10]17]. As in previous studies, all strains of in uenza were detected, with widely varying strain circulation between sites and even neighboring regions.…”

The selection pressure on the neuraminidase gene of influenza viruses isolated in Ukraine from 2009 to 2015

“…Isolation of RNA from the influenza viruses was carried out using the QIAamp® Viral RNA Mini Kit (QIAGEN, Germany) according to the manufacturer's instructions. The reaction mixture for PCR was prepared according to the method for the detection of swine and seasonal A(H1N1)pdm09 influenza viruses as recommended by the CDC (Atlanta, USA) [17]. For the PCR, the Ambion AgPath-IDTM One-Step RT-PCR Kit and a set of primers and probes (Thermo Fisher Scientific, USA) were used.…”