Evaluating Google Flu Trends in Latin America: Important Lessons for the Next Phase of Digital Disease Detection.
BACKGROUND
Latin America has a substantial burden of influenza and rising Internet access and could benefit from real-time influenza epidemic prediction web tools such as Google Flu Trends (GFT) to assist in risk communication and resource allocation during epidemics. However, there has never been a published assessment of GFT's accuracy in most Latin American countries or in any low- to middle-income country. Our aim was to evaluate GFT in Argentina, Bolivia, Brazil, Chile, Mexico, Paraguay, Peru, and Uruguay.


METHODS
Weekly influenza-test positive proportions for the eight countries were obtained from FluNet for the period January 2011-December 2014. Concurrent weekly Google-predicted influenza activity in the same countries was abstracted from GFT. Pearson correlation coefficients between observed and Google-predicted influenza activity trends were determined for each country. Permutation tests were used to examine background seasonal correlation between FluNet and GFT by country.


RESULTS
There were frequent GFT prediction errors, with correlation ranging from r = -0.53 to 0.91. GFT-predicted influenza activity best correlated with FluNet data in Mexico follow by Uruguay, Argentina, Chile, Brazil, Peru, Bolivia and Paraguay. Correlation was generally highest in the more temperate countries with more regular influenza seasonality and lowest in tropical regions. A substantial amount of autocorrelation was noted, suggestive that GFT is not fully specific for influenza virus activity.


CONCLUSIONS
We note substantial inaccuracies with GFT-predicted influenza activity compared with FluNet throughout Latin America, particularly among tropical countries with irregular influenza seasonality. Our findings offer valuable lessons for future Internet-based biosurveillance tools.
Department of Epidemiology & Biostatistics, University of California at San Francisco.|Marie Bashir Institute for Infectious Diseases & Biosecurity, University of Sydney.
Simon
S
Pollett
Department of Epidemiology & Biostatistics, University of California at San Francisco.
W John
WJ
Boscardin
Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia.
Eduardo
E
Azziz-Baumgartner
Department of Virology & Emerging Infectious Diseases, US Naval Medical Research Unit No 6, Callao, Peru.
Yeny O
YO
Tinoco
Department of Virology & Emerging Infectious Diseases, US Naval Medical Research Unit No 6, Callao, Peru.
Giselle
G
Soto
Department of Virology & Emerging Infectious Diseases, US Naval Medical Research Unit No 6, Callao, Peru.
Candice
C
Romero
Centre for Infectious Diseases and Microbiology Laboratory Services, Level 3 Institute of Clinical Pathology and Medical Research, Pathology West, Westmead Hospital, New South Wales, Australia.
Jen
J
Kok
Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia.
Matthew
M
Biggerstaff
Fogarty International Center, National Institutes of Health, Bethesda, Maryland.
Cecile
C
Viboud
Department of Epidemiology & Biostatistics, University of California at San Francisco.
George W
GW
Rutherford
D004196:Disease Outbreaks; D062306:Geography, Medical; D049674:History, 21st Century; D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology* / Q000266:history; D007843:Latin America / Q000453:epidemiology; D011159:Population Surveillance / Q000379:methods; D057386:Search Engine; D012621:Seasons
Google Flu Trends; Latin America; digital epidemiology
Clin Infect Dis. 2008 Dec 1;47(11):1443-8
18954267
Nature. 2009 Feb 19;457(7232):1012-4
19020500
MMWR Morb Mortal Wkly Rep. 2009 May 8;58(17):467-70
19444150
PLoS One. 2011 Apr 27;6(4):e18687
21556151
PLoS Negl Trop Dis. 2011 May;5(5):e1206
21647308
Bull World Health Organ. 2012 Apr 1;90(4):318-20
22511830
Clin Infect Dis. 2012 Oct;55(8):e75-8
22715172
J Infect Dis. 2012 Sep 15;206(6):838-46
22829641
Influenza Other Respir Viruses. 2013 Nov;7(6):1017-32
23210504
PLoS Comput Biol. 2013;9(10):e1003256
24146603
Science. 2014 Mar 14;343(6176):1203-5
24626916
PLoS One. 2014 Jun 23;9(6):e100659
24956184
Am J Prev Med. 2014 Sep;47(3):341-7
24997572
Cad Saude Publica. 2015 Apr;31(4):691-700
25945979
Sci Rep. 2015 Aug 03;5:12760
26234783
PLoS Comput Biol. 2015 Oct 29;11(10):e1004513
26513245
PLoS Curr. 2015 Oct 19;7:null
26543674
Influenza Other Respir Viruses. 2016 Jul;10(4):301-9
26547629
Proc Natl Acad Sci U S A. 2015 Nov 24;112(47):14473-8
26553980
Influenza Other Respir Viruses. 2016 May;10(3):170-5
26701079