Study	Reason for exclusion
Allsup 2001	Elderly denominator 19 and no breakdown of cases by age groups is given
Allsup 2003	See Allsup 2004
Anonymous 1995	Comment
Anonymous 2004b	No data presented.
Ansaldi 2002	Cross‐sectional study
Arden 1986	Review
Armstrong 2004	Data presented cannot be used in the analysis; the statistical model is not comparable with that used in the other studies.
Arroyo 1988	Description of epidemic
Arya 2003	No data presented.
Ayala‐Montiel 2004	No placebo/do nothing comparator: influenza + pneumococcus versus influenza vaccine
Baldo 1999	Lack of a control group
Barker 1980	Cross‐sectional study
Bektimirov 1993	No original data presented.
Belshe 2004	Children and adults
Ben‐Yehuda 2003	No placebo/do nothing comparator
Berg 2004	The study does not investigate the vaccine efficacy.
Buxton 2001	Lack of a control group
Carman 2000	Data are not presented by vaccine condition.
Castilla 2006	Retrospective paper looking at vaccination cover in > 65 and relations with effectiveness claimed as efficacy. Only 60 influenza‐like illness cases were tested out of a total of 2300.
Chen 2004	The study does not investigate the vaccine efficacy.
Chlibek 2002	This could be a cohort study to be considered for the adults review.
Christenson 2002	Same cohorts of Christenson 2001
Chumakov 1992	High‐risk groups
Cohen 2004	Does not present original data
Conne 1997	Lack of a control group
Cruijff 1999	Same cohorts of Govaert 1994a
D'Alessandro 2004	Both arms administered influenza vaccine, no placebo/do nothing comparator.
de Bernardi 2002	Healthy adults; lack of a control group
de Bruijn 2004	Serological outcome only
Deguchi 2000a	Same cohorts of Deguchi 2001
Deguchi 2000b	Same cohorts of Deguchi 2001
Deguchi 2000c	Same cohorts of Deguchi 2001
Deibel 1970	The study does not investigate the vaccine efficacy.
De Serres 2004	Same data set as Skowronski ‐ high‐risk group
Elder 1996	Healthy adults
Ender 2001	Assessment of vitamins before vaccination as immunomodulators
Erofeeva 2001	Frequency data are not reported; outcome is not clearly defined.
Fedson 1992	The study does not investigate the vaccine efficacy.
Fedson 1993	Comment
Fitzner 2001	Economic study without original data
Fukumi 1969	The study does not investigate the vaccine efficacy.
Fukushima 1999	Serological outcome only
Galanti 1976	Data presented cannot be estimated for the analysis.
Galasso 1977	Healthy adults
Garcia‐Doval 2001	Case report
Garcia‐Garcia 2009	Only 16% of participants are over the age of 60.
Gasparini 2002	Economic study; data source not described
Gavira 1990	Economic evaluation
Gendon 1988	No original data presented.
Giglio 1994	Unclear study design; probably retrospective cohort based only on individual recall of disease
Glass 1978	The study does not investigate the vaccine efficacy.
Glezen 1987	The study does not investigate the vaccine efficacy.
Gomez de Caso 1996	The study does not investigate the vaccine efficacy.
Govaert 1994b	Antibody outcomes only
Gowda 1979	The study does not investigate the vaccine efficacy.
Grigor'eva 1994	Study population is children.
Grigor'eva 2002	Study population is children.
Gross 1977	Study population is children.
Gross 1995	Review
Guarino 1977	Serological survey
Guillevin 1983	The study does not investigate the vaccine efficacy.
Gutierrez 2001	Unclear study design; probably retrospective cohort based only on individual recall of disease; 1‐year follow‐up
Hak 1998	High‐risk groups
Hall 1981	The study does not investigate the vaccine efficacy.
Hampson 1997	Economic review
Hara 2008	Redundant publication of Hara 2006
Harling 2004	NI used
Harper 1985	Comment
Hedlund 2003	Same cohorts of Christenson 2001
Helliwell 1988	Economic evaluation
Hennessen 1978	Cross‐sectional study
Herzog 2003	The study does not investigate the vaccine efficacy.
Heymann 2004	Same cohorts of Shapiro 2003
Hirota 1997	Healthy adults
Hoberman 2003	Study population is children.
Hope‐Simpson 1970	The study does not investigate the vaccine efficacy.
Howell 1967	Not elderly
Hurwitz 1983	Non‐comparative data
Icardi 2002	Unclear study design; probably cross‐sectional
Ikematsu 1998	Poorly described study. Influenza‐like illness was defined only as "fever". Deaths from all causes referred to too long a period (from January to September).
Ikematsu 2000	Poorly described study. Influenza‐like illness was defined only as "fever". Asymptomatic infections were indistinguishable from symptomatic ones.
Isahak 2007	Inadequate comparator
Jackson 1999	High‐risk groups
Jackson 2002	High‐risk groups
Jahnz‐Rozyk 2003	Economic evaluation
Jani 1994	Case report
Jarstrand 1974	The study does not investigate the vaccine efficacy.
Jovanovic 1977	Lack of a control group; high‐risk groups
Kaplan 1983	Non‐comparative design
Keavey 1999	No data
King 1997	Comment
Knight 1984	Case report
Knottnerus 1996	Cost‐of‐illness study
Kurland 1984	Non‐comparative study
Landi 2003	1‐year follow‐up in a population with important diseases
Landi 2006	Same data set as Landi 2003
Lavergne 1980	No placebo/do nothing comparator, serological responses and age group?
Lawson 2000	Frequency data not reported.
Lindahl 1999	Case report
Lohse 1999	Case report
Luce 2001	Economic evaluation
Mair 1974	Lack of a control group
Mandal 1973	Descriptive
Manzano 2000	Case report
Manzoli 2007	Feasibility study of general practice reporting method to assess vaccine effectiveness
Margolis 1990b	No placebo/do nothing comparator
Marine 1973	Serological outcome only
Marinich 1997	Serological outcome only
Martin 1997	Lack of a control group
Marwick 1995	Comment
Masurel 1979	Antibody only
Maxim 1998	No data presented.
Mayon‐White 1994	No data presented.
McCall 1996	No data presented.
McCarthy 1978	No data presented.
McElhaney 2002	No data presented.
McGuffey 1993	No data presented.
Meiklejohn 1989	Interruption study
Mendelman 2001	Study population is children and adults.
Meynaar 1991	Comment
Mignogna 2000	Case report
Miller 1975	Lack of a control group
Modlin 1977	Children
Monto 1994	No data presented.
Moreno 2009	Non‐systematic review and meta‐analysis with metaviews back to front
Mostow 1969	Lack of a control group
Mostow 1988	No data presented.
Nguyen‐van‐Tam 1992	Unclear study design
Nichol 1996	Same cohorts of Nichol 1994
Nichol 1999a	No original effectiveness data presented.
Nichol 1999b	Same cohorts of Nichol 1994
Nichol 1999c	High‐risk groups
Nichol 1999d	Adult population
Nichol 2002	Same cohorts of Nichol 1998
Nichol 2007	Data already included in review from other publication by the same author
Nicholson 1979	No placebo/do nothing comparator
Nicholson 1983	Lack of a control group
Nicholson 1990a	Unclear study design; symptomatic participants only
Nicholson 1990b	No data presented.
Nicholson 1992	Unclear study design; symptomatic participants only
Nielsen 1996	No data presented.
Nygaard 1999	No data presented.
Odelin 1993	Lack of a control group
Odelin 2003	Lack of a control group
Ohmit 1995	Same population as Ohmit 1995
Ortqvist 2007	Data already included in the 2005 review; re‐analysis of the same data set
Oshitani 2000	Ecological study
Parkin 1978	Case series
Parsons 1997	No data
Patel 1988	Case report
Patriarca 1985	The study does not investigate the vaccine efficacy.
Patriarca 1994	Comment
Pena‐Rey 2003	The study does not investigate the vaccine efficacy.
Perez 2000	Case report
Perez‐Tirse 1992	Review of economic evaluations
Perucchini 2004	Lack of a control group
Peters 1988	Serological outcomes
Philip 1969	Data are not presented by age.
Phillips 1970	Lack of a control group
Phillips 1971	Comment
Piedra 2002	Study population is children.
Poe 1977	Not about vaccine effectiveness
Poland 2002	Review
Potter 1997	Data are not presented by vaccine condition.
Powers 1991	Serological outcome only
Pregliasco 1997	Not about vaccine effectiveness
Pregliasco 1999	The study does not investigate the vaccine efficacy.
Profeta 1987	Serological outcome only
Provinciali 1994	Unclear study design
Puig Barberà 1995	Review
Puretz 1979	Review
Pyhala 1997	Guideline
Quinlisk 1990	Not about vaccines
Quinnan 1983	Does not report safety outcomes by age group
Rao 1982	Not about vaccines
Read 2000	No outcome data by vaccine status, uncertain denominators
Reedy 2000	Review
Ruben 1973	Serological outcome only
Rubin 1973	No data
Rudenko 1981	Review
Rudenko 1993	Children
Ruel 2002	Only 1 participant was unvaccinated.
Ruf 2004	Antibody titres and no placebo/do nothing comparator
Runehagen 2002	Not about vaccines
Russell 2001	Not about vaccines
Ryan 1984	No placebo/do nothing comparator
Sadler 2000	Not about vaccines
Sandrini 1997	Data only in graphs
Saslaw 1966	Antibody responses
Satsuta 1985	Not about vaccines
Schoenbaum 1969	Poor description; data do not fit the comparison of this review
Schwartz 1995	Comment
Selvaraj 1998	Case report
Serie 1977	Very poor description; absence of definitions, incoherence between data reported in text and data reported in tables
Sethi 2002	Not about vaccines
Sharbaugh 1997	Descriptive study
Shinkawa 2002	No data
Shoji 2003	Comment
Siewert 1988	The study does not investigate the vaccine efficacy.
Simonsen 2005	Ecological study
Skowronski 2003	High‐risk groups
Skull 2009	Study assessing risk factors for community‐acquired pneumonia. Insufficient data presented for evaluation of influenza vaccine effectiveness.
Slepuskin 1967	Ecological study
Sloan 1993	Comment
Socan 2004	Lack of a control group
Solomon 1984	Case report
Solomon 1996	Case report
Solomon 1999	Case report
Spencer 1979	Healthy adults
Sprenger 1990	The study does not investigate the vaccine efficacy.
Squarcione 2003	No placebo/do nothing comparator
Stamboulian 1999	Unclear study design
Stott 2001	Letter with no data
Tamblyn 1997	Comment
Thompson 1988	Review
Treanor 1992	Lack of a control group
Treanor 1998	Lack of a control group
Tsai 2007	Model based on aspecific outcomes
Upshur 2000	Descriptive study
Urquhart 1974	Antibody titres
Uyeki 2003	The study does not investigate the vaccine efficacy.
Vallee 2000	No data presented.
Van Horren 1976	Not about effectiveness
van Vuuren 2009	Insufficient data
Verde 1973	Serological outcomes
Verweij 2002	Ethical study
Vila‐Corcoles 2005	Insufficient data reported.
Visconti 1973	Serological outcomes
Voordouw 2004	Lack of a control group
Voordouw 2006	Insufficient data reported (denominators are not reported).
Vu 2002	Review
Wagner 1993	Lacks controls
Wagner 1994	Comment
Wakefield 1990	The study does not investigate the vaccine efficacy.
Wang 1986	Comment
Wang 2002	1‐year follow‐up
Warburton 1972	Ecological study
Wareing 2001	Review
Watson 1997	Review
Weaver 2001	The study does not investigate the vaccine efficacy.
Wiehl 2001	Comment
Williams 1980	Comment
Wilson 1994	Comment
Winer 1984	Survey of cases
Wise 1977	Healthy adults
Wood 2000	Review
Woratz 1984	Methodological paper
Yassi 1993	Vaccine and amantadine were used to control outbreak: amantadine acts as confounder.
Zambon 2001	The study does not investigate the vaccine efficacy.
Zimmerman 2004	Not about vaccine effectiveness
Zoffmann 1977	Not about vaccine effectiveness
Zourbas 1973	Serological outcome only
Zuckerman 1990	Serological outcome only
Zuckerman 1992	Serological outcome only
Zuckerman 1993	Serological outcome only

NI: neuoraminidase inhibitors