Baja eficacia de la vacuna antigripal en hemisferio sur.

http://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2017.22.43.17-00707#

Eurosurveillance | Low interim influenza vaccine effectiveness, Australia, 1 May to 24 September 2017

 

The ongoing Australian 2017 influenza season was so far characterised by record-high laboratory-confirmed influenza notifications [], high consultation rates, high hospitalisation and mortality rates, particularly in New South Wales [], large numbers of institutional outbreaks [] and media attention. The southern hemisphere influenza vaccine used in Australia for this season was a quadrivalent formulation comprised of an A/Michigan/45/2015 (H1N1)pdm09-like virus, an A/Hong Kong/4801/2014 (H3N2)-like virus, a B/Brisbane/60/2008-like virus (of the B/Victoria/2/87 lineage) and a B/Phuket/3073/2013-like virus (of the B/Yamagata/16/88 lineage) [,]. This same vaccine composition is being used in the upcoming northern hemisphere for the 2017/18 influenza season []. Here we report interim influenza vaccine effectiveness estimates for 2017 in Australia, using sentinel surveillance data.

The Australian Sentinel Practices Research Network (ASPREN) and the Victorian Sentinel Practice Influenza Network (VicSPIN) constitute Australia's two sentinel influenza general practice (GP) networks. VicSPIN operates in the state of Victoria, while ASPREN operates nationally. Both surveillance systems use similar data collection methods [,], with the key difference that the VicSPIN surveillance period is limited to weeks 18 to 43 (1 May 1– 29 October), timed to start roughly 2 weeks after vaccination campaigns in mid-April. Briefly, sentinel GPs submit weekly reports of the number of patients seen with influenza-like illness (ILI), defined as fever/history of fever, cough and fatigue, and the total number of patients. Nose/throat swabs are collected from a subset of patients with demographic data, date of ILI onset, vaccination status (self-reported or medical record) and indications for vaccination, such as belonging to an influenza risk group. Swabs are tested by RT-PCR and positive samples are referred to the World Health Organization (WHO) Collaborating Centre for Reference and Research on Influenza in Melbourne, for antigenic characterisation by haemagglutination inhibition assay (HAI) [] or focus reduction assay (FRA) [] and genetic sequencing, as described previously []. All data were managed and analysed using R version 3.4.1.

ILI data from ASPREN for 2017 and 2012 to 2016 (averaged) are plotted in and indicate consultation rates were higher in 2017 than in the previous 5 years. For the study period from 1 May 2017 to 24 September 2017, i.e. weeks 18–38, the 262 ASPREN GPs and 88 VicSPIN GPs conducted 493,961 consultations, of which 5,678 (1.1%) met the ILI case definition and swabs were collected from 2,465 (43%) of them. Influenza cases were detected in every week of the study period and peaked in week 34 (21–27 August, n = 235). Percentage of positive samples peaked in week 32 (7–13 August) with 58%.

Figure 1

Sentinel general practice (GP) surveillance data^a, (A) ILI consultation rates, (B) laboratory detections of influenza patients by week and type/subtype, Australia, 2 January–24 September 2017