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Bibliometric analysis of scientific output on influenza in Mexico, 2000-2012

How to cite this article: Castillo-Pérez JJ, Muñoz-Valera L, García-Gómez F, Mejía-Aranguré JM. Bibliometric analysis of scientific output on influenza in Mexico, 2000-2012. Rev Med Inst Mex Seguro Soc. 2015 May-Jun;53(3):294-301.



Received: April 15th 2014

Accepted: July 29th 2014

Bibliometric analysis of scientific output on influenza in Mexico, 2000-2012

José Juan Castillo-Pérez,a Luz Muñoz-Valera,a Francisco García-Gómez,b Juan Manuel Mejía-Aranguréc

aGrupo de Estudios Métricos de la Información en Salud (EMIS)

bCoordinación del Centro Nacional de Investigación Documental en Salud (CENAIDS), Centro Médico Nacional Siglo XXI / EMIS

cCoordinación de Investigación en Salud

Instituto Mexicano del Seguro Social, Distrito Federal, México

Communication with: José Juan Castillo-Pérez

Telephone: (55) 5627 6900, extension 21633

Background: During the spring of 2009, H1N1 influenza became the first pandemic of the 21st century. There are no bibliometric studies in Mexico that have analyzed this topic in relation to the generation of Mexican knowledge. The aim of this article is to determine the volume and impact of Mexican scientific output published in journals indexed in Science Citation Index (SCI) on influenza from January 1, 2000, to October 1, 2012.

Methods: All the documents within SCI whose topic was influenza were included; in order to do this, we used the describers influenza or swine flu H1N1. The analysis included authorship, international collaboration, journals, document type, citations and address of correspondence.

Results: In 2000-2012, 241 articles related to influenza were published. The years with the highest number of articles were 2009 (n = 53) and 2010 (n = 62). The journals with the highest quantity of papers were Salud Pública de México (n = 16), PLOS ONE (n = 13), Archives of Medical Research (n = 13) and Vaccine (n = 10). The most investigated area was infectious diseases (18.9 %), followed by internal medicine (14 %) and immunology (14 %), occupational health (13 %) and experimental medicine (12.3 %).

Conclusion: The scientific output on influenza supposes near 1 % of the total of the medical-scientific production with a decline posterior to the outbreak of 2009 pandemic influenza.

Key words: Bibliometrics; H1N1 subtype Influenza A virus; Scientific output; Bibliometric indicators

Infectious diseases have long been a threat to humans, especially when social conditions have changed continually.1

Despite the growing interest in information on pandemic influenza, in Mexico little it is known about the volume of scientific production of Mexican researchers. A widely used tool for this purpose is the bibliometric analysis, which is a research method used in information sciences to evaluate the performance of research through quantitative bibliometric indicators.2 This method describes the pattern of publications on a subject, a field, an institution or a country.3,4

The detailed analysis of literary production provides information to researchers and represents their past, current or future trends.5 This is evidenced by the progressive inclusion of such indicators in evaluation studies of scientific activity and its presence in many of the publications that are written periodically on science and technology indicators, both in the European Union and the United States.6

A common method for carrying out bibliometric analysis is the use of the database Science Citation Index, consulted worldwide, created by the Institute for Science Information (now Thomson Reuters),7 although in recent years Scopus from European publisher Elsevier has been used.8

The aim of this study is to determine, through bibliometric techniques, the volume, the impact, and the tendency of Mexican scientific production on the subject of influenza from January 2000 to October 2012, based on information from the Web of Science (WoS) database. The results of this study may be useful for researchers and decision makers on the issue of research policy to trace the current trend and future direction of research on influenza.


This is a documentary retrospective study performed on the Science Citation Index (SCI) database of Thomson Reuters7 whose unit of study was the scientific article published in a periodical journal indexed in Journal Citation Reports (JCR). Access to this database was made through the Universidad Nacional Autónoma de México.

The search strategy to extract publications by Mexican researchers was to use the descriptor influenza in the subject field (topic) and the descriptor mexico in the affiliation field (address); new mexico was excluded from that field.

Topic = (influenza) AND Address = (mexico) NOT Address = (new mexico)

The period investigated was the first of January 2000 to the first of October 2012, as current information.

Timespan = 2000-01-01 - 2012-10-01. Databases = SCI-EXPANDED, SSCI. Lemmatization = On

Note that in the consultation on the topic, the term swine flu H1N1 was also included.

We considered any citable document indexed in the JCR. In each document we obtained author data such as name, affiliation, position in the article, correspondence, country, language of the document, and document type.

The search strategy yielded 243 records from January 2000 until the first of October 2012. The data were loaded and prepared on an MS Excel sheet for descriptive analysis. The names of the signatories and institutions were standardized; the names of the authors were associated with the name of the institution even if it was abbreviated, shortened, an acronym, or translated into English.

We are excluding two documents (original articles) because one was related to the issue of nutrition (and not with the subject matter) and the other had foreign signatories; 241 documents were left for analysis.

We include information on membership of the signatories, the first author’s country, citation count, medical specialty of the article, type of document, and journal type. The impact factor (IF) was determined for each journal as reported in JCR9 2011, as the latest version available on the WoS.

We also did a search in ScienceDirect8 and obtained 50 articles on the topic of influenza. These items were already included in the WoS database.

pub-date> 1999 and TITLE (influenza) and AFFILIATION (mexico) and not AFFILIATION (new mexico

The time period considered for the analysis was divided into two periods, the first from 2000 to 2008 (before the pandemic) and the second from January 2009 to October 2012 (during and after the pandemic), in order to understand the trend of scientific production.

Version 4.5 of WoS system provides some important bibliometric results, such as the subject classification, the H index, citations, and other measures of interest.10 Note that this classifies a document in one or more areas of research according to MeSH terms used for article identification.
Descriptive data analysis of was done using MS Excel. We only used bibliometric indicators from generated documents, citation count, and distribution by institution, since the purpose of the study was not to compare production among academic of health institutions or research centers in Mexico.


Scientific production about influenza, 2000-2012

A total of 241 articles published about influenza in 121 journals were obtained. Considering the 13-year period, an average of 18.5 articles were produced yearly with a standard deviation of 21 items and a range of 1-62 items.

For the 2000-2008 period there was a significant increase of 1.4 articles annually, p = 0.005 (Figure 1). During this period, 24.1% of total production on the subject was published.

Figure 1 Trends in scientific production about influenza, 2000-2012 period (p < 0.05)
Source: Web of Science database from Thomson Reuters [consulted October 2012]

In the two-year period of the pandemic, publications on influenza rose exponentially relative to the previous period, representing 47.7% of total production (115 of 241 publications); however, for the two years 2011-2012 there was a decrease of 41% of literary production in contrast to the 2009-2010 period.


The most active journals in this area during the period considered (≥ 2 documents) were Salud Pública de México, PLOS ONE, Archives of Medical Research, and Vaccine; these four journals published 6.6%, 5.3%, 5.3% and 4.1% of the total articles, respectively (Table I). The average impact factor of the journals was 2.7 with a range of 0.08 to 53,298. Mexican researchers published 22.2% of the pieces in seven Mexican journals and 77.8% in foreign journals.

Table I Journals in which scientific literature on influenza by Mexican researchers was published in 2000-2012 period Magazines Table I in which the scientific literature on influenza Mexican researchers published in the period 2000-2012
Journal name Journal country Articles % IF
Salud Publica Mex Mexico 16 6.64 0.941
PLOS ONE United States 13 5.39 4.092
Arch Med Res Mexico 13 5.39 1.733
Vaccine Netherlands 10 4.15 3.766
Gac Med Mex Mexico 9 3.73 0.221
Rev Invest Clin Mexico 8 3.32 0.419
Emerg Infect Dis United States 5 2.07 6.169
Influenza Other Resp Vir England 5 2.07 4.157
Int J Infect Dis Canada 5 2.07 1.938
Cir Cir Mexico 5 2.07 0.138
J Virol United States 4 1.66 5.402
Avian Dis United States 4 1.66 1.462
New Engl J Med United States 3 1.24 53.298
Lancet United States 3 1.24 38.278
Science United States 3 1.24 31.201
J Rheumatol Canada 3 1.24 3.695
Pediatr Infect Dis J United States 3 1.24 3.577
Am J Trop Med Hyg United States 3 1.24 2.592
Poultry Sci United States 3 1.24 1.728
Vet Rec England 3 1.24 1.248
Rev Panam Salud Publica United States 3 1.24 0.847
Jama United States 2 0.83 30.026
Plos MED United States 2 0.83 16.269
Clin Infect Dis United States 2 0.83 9.154
Am J Transplant United States 2 0.83 6.394
Aids England 2 0.83 6.245
Euro Surveill European Union 2 0.83 6.153
Eur Respir J Switzerland 2 0.83 5.895
J Infect England 2 0.83 4.126
J Hosp Infect England 2 0.83 3.393
Epidemiol Infect England 2 0.83 2.843
Clin Vacc Immunol United States 2 0.83 2.546
Virol J England 2 0.83 2.343
Value Health United States 2 0.83 2.191
Transbound Emerg Dis Germany 2 0.83 1.809
J Infect Dev Ctries Italy 2 0.83 1.191
Med Intensiva Spain 2 0.83 1.072
Tec Pecu Mex Mexico 2 0.83 0.4
IF = impact factor from Journal Citation Reports 2011

Ten of the journals in which Mexicans published their work had an impact factor greater than 10, and these published 7.4% of the articles. 26% of papers were published in journals with impact factor less than 1. Among these are Mexican journals as Gaceta Médica de México (8 items), Cirugía y Cirujanos (5 items) and Veterinaria de México (1 item). English dominated the scientific production with 83.8% of the total, and the remainder was articles published in Spanish.

Authors and institutions

The total of unique signatories was 1399 with an average of 7.7 signatures per document, a standard deviation of 6.5 and a range of one to 59 signers. The items were ranked by the number of signatories: in the 13-year period a total of 11 articles were signed by only one author (4.6%), either first author or co-author, 19 by two authors (7.9%), 24 by three ( 9.96%) and one single article had 59 signatories, as shown in Figure 2. On the other hand, we note that 18 items involved 360 signatories, averaging 22.5 authors per article.

Figure 2 Distribution of authors by article, 2000-2012 period

70.95% of the principal authors and 34.85% of the correspondents were Mexican. Those who generated six or more items on the issue were considered highly active authors (Table II).

Table II Authors with more than 5 articles published about influenza in 2000-2012 period
Author Institution Articles % Citations
x* (min-max)
Chowell, Gerardo Arizona State University, USA 11 4.56 38.8 (0-289)
Noyola, Daniel E Universidad Autónoma de San Luis Potosí, Mexico 10 4.15 10.1 (0-27)
Dominguez-Cherit, Guillermo Instituto Nacional de Ciencias Médicas y Nutrición, Mexico 8 3.32 43.4 (0-339)
Miller, Mark A National Health Institute, USA 8 3.32 43.4 (0-289)
Hernández-Ávila, Mauricio Secretaría de Salud, Mexico 8 3.32 114.5 (0-567)
Pérez-Padilla, José Rogelio Instituto Nacional De Enfermedades Respiratorias, Mexico 8 3.32 80.9 (1-567)
Ruiz-Palacios, Guillermo M Instituto Nacional de Ciencias Médicas y Nutrición, Mexico 8 3.32 59.7 (0-339)
Alpuche-Aranda, Celia M Instituto de Diagnóstico y Referencia Epidemiológicos (INDRE), Mexico 7 2.90 237.7 (5-738)
Santos-Preciado, José Ignacio Universidad Nacional Autónoma de Mexico, Mexico 7 2.90 6.0 (0-35)
López-Martínez, Irma Instituto Nacional de Salud Pública, Mexico 7 2.90 110.4 (0-738)
Viboud, Cecile National Health Institute, USA 7 2.90 8.1 (0-17)
Del Río, Carlos Emory University, USA 6 2.49 7.0 (0-19)
Franco-Paredes, Carlos Emory University, USA 6 2.49 7.3 (0-35)
Bautista, Edgar Instituto Nacional de Enfermedades Respiratorias, Mexico 6 2.49 199.8 (1-567)
Borja-Aburto, Victor Hugo Instituto Mexicano del Seguro Social, Mexico 6 2.49 28.5 (0-147)
Ponce de León-Rosales, Samuel Birmex - Laboratorios de Biológicos y Reactivos de Mexico, S.A. de C.V. 6 2.49 100.8(0-567)
* Average citations during period (total citations in period between number of articles)

Regarding the country of the main authors, we note that during the period 2000-2012, Mexico contributed 70.9% (n = 171), followed by the US with 16.2% (n = 39), Canada with 3.3% (n = 8), Spain and the UK published 1.2% each (n = 3), Germany, Argentina, Australia, and Italy 0.8% each (n = 2) and for Brazil, Colombia, China, Finland, Japan, Malaysia, Switzerland, Uruguay, and Vietnam each country had an author who published one article.

According to the WoS it was found that among national institutions the Universidad Nacional Autónoma de México (UNAM) dominated production on the theme of influenza with 24.5%, followed by the Instituto Nacional de Enfermedades Respiratorias (INER) with 8.2%, the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán (INCMN SZ) with 7.4%, the Instituto Nacional de Salud Pública (INSP) and the Instituto Mexicano del Seguro Social (IMSS), each with 6.2%, to name the most common.

According to results from the WoS on affiliation of the signatories, Mexico worked with 24 countries: eight European, seven Asian, five Latin American, two American (US and Canada), one African, and one from Oceania (Australia). Institutions in the United States collaborated on 33% of production, followed by Canada with 7.41% and England with 5.35%. Five Latin American countries (Brazil, Argentina, Colombia, Chile and Peru) collaborated with Mexico in literary production with 9.9%.

Characteristics of scientific production

Mexican production comprised of 175 original articles (72.6%), 22 conference abstracts (9.13%), 19 revisions (7.8%), 15 editorials (6.22%) and 10 letters to the editor (4.15%).

The WoS classified scientific production by research area​​, as shown in Table III, where the highest percentage corresponds to infectious diseases (18.9%), followed by internal medicine (14%) and immunology (14%). The field of knowledge with the highest frequency was clinical and health with 54%, followed by basic research with 35%, and social medicine with 11% of production.

Table III Distribution by research topics in 2000-2012 period
Research area* Field of knowledge Articles %
Infectious diseases Clinical/Medical 46 18.93
Internal medicine Clinical/Medical 34 13.99
Immunology Biomedical/Basic 34 13.99
Occupational health Social-medical 31 12.76
Experimental medical research Clinical/Medical 30 12.35
Veterinary sciences Biomedical/Basic 21 8.64
Virology Biomedical/Basic 18 7.41
Life sciences and others Clinical/Medical 16 6.58
Microbiology Biomedical/Basic 9 3.70
Respiratory system Clinical/Medical 7 2.88
Surgery Clinical/Medical 7 2.88
Molecular biology Biomedical/Basic 6 2.47
Agriculture Biomedical/Basic 5 2.06
Biotechnology applied to biology Biomedical/Basic 5 2.06
Neurology and neurosciences Clinical/Medical 5 2.06
Pediatrics Clinical/Medical 4 1.65
Rheumatology Clinical/Medical 4 1.65
Technological sciences and others Clinical/Medical 4 1.65
Tropical medicine Clinical/Medical 4 1.65
Environmental science, ecology Biomedical/Basic 3 1.24
Health services Social-medical 3 1.24
Medical-laboratory technology Biomedical/Basic 3 1.24
Pathology Clinical/Medical 3 1.24
Pharmacology Biomedical/Basic 3 1.24
Biophysics Biomedical/Basic 2 0.82
Business Social-medical 2 0.82
Hematology Clinical/Medical 2 0.82
Biomathematics Biomedical/Basic 2 0.82
Nutrition Clinical/Medical 2 0.82
Oncology Clinical/Medical 2 0.82
Transplants Clinical/Medical 2 0.82
*Classification by Web of Science 4.5 from Thomson Reuters

Regarding the citations, in the period analyzed the literary production received 3212 citations, with 99 self-citations and 17.9 average annual citations per document, with a range of 0-738 citations. The articles in the first period were cited 669 times and only 10 items were not referred to. The articles published in the period from January 2009 to October 2012 were referred to 3654 times. Seventy-six articles in this period have not received any citations. There were eight items with more than 100 citations. This included three original research articles, published in 2009, that received 738, 579, and 567 citations. We note that 46% of the production has received between 1 and 10 citations, and 9.1% has a range from 11 to 20 citations (Table IV).

Table IV Distribution of annual production by category of number of bibliographic citations
Publication year Citations Total articles
0 1-10 11-20 21-50 51-100 > 100
2000 1 - - - - - 1
2001 - - - - - - 0
2002 - 2 3 - - - 5
2003 - - 2 - 1 - 3
2004 1 5 1 1 - - 8
2005 3 4 1 1 - 1 10
2006 2 6 3 2 - - 13
2007 1 6 - - - - 7
2008 2 7 1 1 - - 11
2009 13 24 6 4 - 6 53
2010 25 30 3 3 - 1 62
2011 17 25 2 1 - - 45
2012 21 2 - - - - 23
86 111 22 13 1 8 241


The use of the scientific literature as a measure of research activity has become important in the assessment and use of scientific information. This study provides a bibliometric analysis (divided into two periods) of Mexican scientific production on the subject of Influenza over the last 13 years. This allows an overview of research before, during, and after the pandemic. The databases Web of Science from Thomson Reuters and Science Direct (Scopus) from Elsevier were used as sources, being the databases most used for this type of analysis.11,12

One limitation of the study was having used data from the WoS, seeing as this indexes mostly Anglo-Saxon journals. National databases such as Artemis and some Latin American indexes such as SciELO were not used; however, we should mention that most national journals are local, and in addition the Mexican indices do not allow extracting information related to the signatories and documents. Artemis searches, for example, must be done manually, i.e., one must download the article and record the required information. Journals compiled (registered) in the WoS and Scopus have international visibility, plus the WoS includes journals with impact factor, a measure considered for curricular evaluations of many research institutions, a characteristic that most Mexican journals do not have.

Another limitation of the study is that despite the standardization of institutional affiliations of the signatories, is well known that many researchers have two or three affiliations and do not adequately establish their institutions.13 Both WoS and Scopus standardize institutional signatures associated with the authors, but still the production of any institution could be under- or overestimated.

Bibliometric studies in Mexico are scarce despite the benefits they bring not only to know the vitality of a particular discipline and to identify areas of interest, but also for the position of a country in international context.

It is difficult to compare the results of this study with previous data or similar studies, because the bibliometric area is little addressed and little used by decision-makers in our country. Studies have been done like those of Bravo Vinaja14 or Rojas Sola,15 on agricultural science and hydraulic engineering respectively, but our review did not identify complete bibliometric studies in the health area​​.

We found a study conducted in 2011 by the Foro Consultivo Científico y Tecnológico that establishes the ranking of Mexican scientific production16 for the period 2003-2009, by using the WoS, version 3.0. In that study, Mexican production is led by the UNAM, followed by national institutes of health, which remains constant in this work. Within this study, in the period 2003-2009 and according to the Spanish research group SCIMAGO,17 Mexican scientific production in the health sector generated 14,073 documents; in our study we identified 115 documents for the same period, representing 0.82% of the total national production for the health sector.

The production of publications during the pandemic was evident; however, there appears to be no continuity or at least it is not reflected in the number of publications, because in the last two years a significant decrease in the trend was seen. The low production may be because there are no researchers or research groups with specific lines of research on influenza, plus it has not been considered by the decision-makers of health and academic institutions, perhaps due to lack of science and technology infrastructure for such research.

In this regard, according to the topic (Table III) 60% of the production identified was in the field of clinical knowledge, i.e., 193 items (60%) described medical conditions, epidemiological aspects of the affected population, and health strategies used by the Mexican health system, such as epidemiological fence. 28.2% of articles (90 documents) were associated with the biomedical field. It is noteworthy that although textual analysis was not performed, according to the MeSH terms of the articles, no article estimated new cases of influenza.

The analysis period was divided into two sections, 2000-2008 and 2009-2012, because the data distribution is not linear. You can see that the first period had an annual increase of 1.4 articles on the subject addressed, and in the second period we observed that 2010 had the highest peak, 62 documents related to the year of the pandemic, and for following years we observe a decrease in production in 2011 and 2012 of 27.4 and 63%, respectively. Importantly, influenza still remains dormant in our country; just in March 2012 the Secretaría de Salud reported 5876 cases and 229 confirmed deaths from influenza A (H1N1).18

In relation to international collaborations, we note that Mexican researchers seek partnerships with prominent nations like the US, the most common country, seeing that academic connections, such as with the University of Arizona or research centers such as the Centers for Disease Control and Prevention (CDC) in Atlanta, are ever stronger. Collaboration with Latin American countries is low, despite increasing involvement of regional countries that have managed to overcome the unfavorable conditions prevailing against scientific development and competition.19


Influenza in Mexico should not only be a seasonal infectious disease but must be a subject of research. The pattern of publication on influenza in the years of the pandemic suggests an immediate summons, a low rate of collaboration, and a dominance by Anglo-Saxon journals.

Our study provides data suggesting that decision-makers generate research policies aimed at supporting research groups, as well as creating networks of collaboration20 between Mexico and other Latin American countries, in addition to strengthening those existing with the United States. In that regard, it is necessary to issue health policies that allow for a more optimal response from the Mexican health system.

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Conflict of interest statement: The authors have completed and submitted the form translated into Spanish for the declaration of potential conflicts of interest of the International Committee of Medical Journal Editors, and none were reported in relation to this article.

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