ABSTRACT
Nowadays, more and more people surf the Internet seeking health-related information. Information and communication technologies (ICTs) can represent an important opportunities in the field of Public Health and vaccinology.
The aim of our current research was to investigate a) how often people search the Internet for vaccination-related information, b) if this search is spontaneous or induced by media, and c) which kind of information is in particular searched. We used Google Trends (GT) for monitoring the interest for preventable infections and related vaccines.
When looking for vaccine preventable infectious diseases, vaccine was not a popular topic, with some valuable exceptions, including the vaccine against Human Papillomavirus (HPV). Vaccines-related queries represented approximately one third of the volumes regarding preventable infections, greatly differing among the vaccines. However, the interest for vaccines is increasing throughout time: in particular, users seek information about possible vaccine-related side-effects. The five most searched vaccines are those against 1) influenza; 2) meningitis; 3) diphtheria, pertussis (whooping cough), and tetanus; 4) yellow fever; and 5) chickenpox.
ICTs can have a positive influence on parental vaccine-related knowledge, attitudes, beliefs and vaccination willingness. GT can be used for monitoring the interest for vaccinations and the main information searched.
KEYWORDS: Google Trends, vaccination, Web 2.0
Introduction
Vaccination represents an important, effective tool for preventing infectious diseases or, at least, reducing their burden. Therefore, ensuring a high acceptance and coverage rate during vaccination campaigns is crucial.1 However, phenomena such as anti-vaccination2 and vaccine hesitancy,3,4 vaccine resistance or vaccine refusal5 could jeopardize what has been achieved so far thanks to herd immunity, leading to re-emerging infectious diseases and outbreaks.
Clinicians still represent a fundamental source of health-related information,1 even though in the last years the Internet has rapidly become a widely used source of information, thanks to the rise of interactive content and social networking (e.g., Facebook, Twitter and YouTube, among others). This “new” Internet, termed as “Web 2.0,” is characterized by the blurring of the difference between the user and the webmaster: the user is, at the same time, both consumer and producer (the so-called prosumer model).6 The Web, and in particular the Web 2.0, has deeply changed the way that people can use the Internet to seek information on vaccines.7-9 In Holland, 45.8% of parents do not judge sufficient the information received by the Dutch National Immunization Program and actively search for extra information.7 According to a cross-sectional study performed by Bianco and colleagues, 29.6% of Italian parents search for vaccination.8 Searching the web for vaccination-related information can have a positive impact on vaccination willingness. McRee and collaborators investigated the Internet-related behaviors of North Carolina parents of daughters and found that mining the Web looking for information about HPV vaccine was a predictor of higher level of HPV knowledge, disease perception and vaccination willingness and a predictor of lower level of vaccination hesitancy and worriness for vaccination-related side effects.9 In a study performed by Barak-Corren and Reis in Israel, Internet-related activities were a proxy of vaccination compliance.10
On one hand, the widespread use of rapidly updated, interactive content has not only increased the potential audience base for Internet based information, but has made impossible to regulate and discipline from a normative point of view the information that reaches parents searching for vaccine information. Even though vast and abundant,11 information available in the Internet is not always reliable. Further, much of the Internet-based vaccine information that reaches parents contains content that overly discourages vaccination practices.12-14 This content is displayed in pages which are frequently returned from search engines and are high-ranked.15 Further, this content is reported adopting a language that mimics scientific standards, trying to legitimate itself and claiming scientific veracity.12 The information in the Web regarding MMR 16 is generally consistent and reliable, but websites do not report accurate, complete and consistent information about influenza,17 and HPV,18 among others. Some information, for example concerning antenatal vaccinations, is even lacking in the Web.19 This can have a negative impact on parental decision, even among educated parents.20 A study performed in the USA found that first-time expectant mothers searching for vaccine-related information in the Internet were more likely to delay one or more recommended vaccinations.21
On the other hand, workers in the field of the Public Health can exploit the new technologies22 in order to provide lay-people with updated, neutral and credible information, increase vaccine confidence.23 For example, the State Health Departments in the USA exploit Facebook to post vaccine-related information (7% of the totally posted content).22 In particular, considering that a decisional process is computationally complex and taking into account the interactive, multidimensional, multi-tasking nature of the Web 2.0, the Internet can represent the proper platform to support and facilitate the decision whether to vaccinate or not.24,25 Information alone, indeed, is not enough: it can create awareness and facilitate acceptance, but results more effective when actively supported.26,27 Some examples of Internet-based platforms are: GoHealthyGirls.org,28,29 VaccinarSi30 and the project “Hermes,” which is trying to promote Internet αbetization among pediatricians in the Region Tuscany (Italy). These aids appear to be effective and also cost-effective.31
The Internet can be exploited also for promoting vaccination-related advocacy32 and for increasing education among health-care workers,33 especially in low- and middle-income countries (LMICs).34 In an investigation performed in Melbourne, Australia, the Internet proved to be an effective mean for increasing participation and coverage rate during the influenza vaccination campaign.35
The aim of our current research was to investigate a) how often people search the Internet for vaccination-related information, b) if this search is spontaneous or induced by media, and c) which kind of information is in particular searched.
Results
In general, the interest for vaccines as general topic is stable throughout the period 2004-present, apart from a peak in November 2009, associated with the 2009 pandemic influenza (Fig. 1). The used keywords for top and rising queries and top and rising topics related to preventable infectious diseases and vaccination, as well as the chosen time period, are shown in Table 1.
Figure 1.
Interest toward vaccines in the study period 2004–2015 as captured by Google Trends.
Table 1.
List of preventable infectious diseases mined in the present study, together with the used keyword(s) both for the infectious disease and the corresponding vaccine. The period of time in which the query was performed is also indicated.
| Preventable infectious diseases | Used keyword(s) for the infectious disease | Used keyword for the vaccine | Period time |
|---|---|---|---|
| Anthrax | Anthrax [Disease] + Anthrax bacterium [Bacteria] + 2001 Anthrax attack [Event] | Search topic option not available | From inception |
| Cervical Cancer (Human Papillomavirus) | Cervical cancer [Disease or medical condition] | HPV vaccines [Vaccine] | From 2006 on |
| Diphtheria | Diphtheria [Disease or medical condition] | Diphtheria vaccine [Drug] + DTP vaccine [Vaccine] | From inception |
| Hepatitis A | Hepatitis A [Infectious disease] | Hepatitis A vaccine [Vaccine] | From inception |
| Hepatitis B | Hepatitis B [Infectious disease] | Hepatitis B vaccine [Vaccine] | From inception |
| Haemophilus influenzae type b (Hib) | Haemophilus influenzae [Bacteria] | Hib vaccine [Vaccine] | From inception |
| Human Papillomavirus (HPV) | HPV* | HPV vaccines [Vaccine] | From 2006 on |
| Influenza (Flu) | Influenza [Infectious disease]+ Influenza A virus [Virus] + Influenza A virus subtype H1N1 [Cause of death] + 1918 flu pandemic [Disaster] | Influenza vaccine [Vaccine] | From inception |
| Japanese encephalitis (JE) | Japanese encephalitis | Japanese encephalitis vaccine [Drug] | From inception |
| Measles | Measles [Contagious disease] | Measles vaccine [Condition prevention factors] + MMR vaccine [Vaccine] | From inception |
| Meningococcal infection | Meningitis [Medical condition] + Meningococcus [Bacteria] | Meningococcal vaccine [Vaccine] | From inception |
| Mumps | Mumps [Viral disease] + Mumps virus [Virus] | MMR vaccine [Vaccine] | From inception |
| Pertussis | Pertussis [Contagious disease] + Bordetella Pertussis [Bacteria] | Pertussis vaccine [Drug] | From inception |
| Pneumococcal infection | Streptococcus pneumoniae [Bacteria] + Pneumococcal pneumonia [Disease or medical condition] | Pneumococcal vaccine [Medical treatment] | From inception |
| Polio | Poliomyelitis [Infectious disease] + Poliovirus [Disease cause] | Polio vaccine [Vaccine] + DTP vaccine [Vaccine] | From inception |
| Rabies | Rabies [Viral disease] + Rabies virus [Virus] | Rabies vaccine [Vaccine] | From inception |
| Rotavirus | Rotavirus [Virus] | Rotavirus vaccine [Topic] | From inception |
| Rubella | Rubella [Disease] + Rubella virus [Disease cause] | Rubella vaccine [Drug] + MMR vaccine [Vaccine] | From inception |
| Shingles (Herpes Zoster) | Shingles [Viral disease] | Zoster vaccine [Vaccine] | From 2006 on |
| Smallpox | Smallpox [Infectious disease] | Vaccination against smallpox [Topic] | From inception |
| Tetanus | Tetanus [Disease or medical condition | DTP vaccine [Vaccine] | From inception |
| Typhoid fever | Typhoid fever [Disease] | Search topic option not available | From inception |
| Typhus | Typhus [Disease] + Epidemic typhus [Disease] | Search topic option not available | From inception |
| Tuberculosis (TB) | Tuberculosis [Infectious disease] + Latent tuberculosis [Disease] | BCG vaccine [Vaccine] | From inception |
| Varicella (Chickenpox) | Chickenpox [Contagious disease] | Varicella vaccine [Vaccine] | From inception |
| Yellow Fever | Yellow fever [Viral disease] + Yellow fever mosquito [Insect] | Yellow fever vaccine [Drug] | From inception |
search term option
Generally speaking, when looking for vaccine preventable infectious diseases, vaccine was not a popular topic, with some valuable exceptions, including the vaccine against HPV (Table 2). Vaccines-related queries represented approximately a third of the queries generated by looking for infections, namely 31.10 ± 56.70% of the volumes regarding preventable infections (median 10.89%; range 1.72–230.00%).
Table 2.
Top and rising queries and top and rising topics related to preventable infectious diseases and vaccination in the study period 2004–2015 as captured by Google Trends. Abbreviations: RSV (Relative Search Volume).
| Preventable infectious diseases | Related top query | Related rising query | Related top argument | Related rising argument | Ratio RSV preventable disease/RSV related vaccine (%) |
|---|---|---|---|---|---|
| Anthrax | Not among the first 10 | Not among the first 10 | Not among the first 10 | Not among the first 10 | — |
| Cervical Cancer (Human Papillomavirus) | Not among the first 10 | 1 | 1 | 1 | 17.31 |
| Diphtheria | Not among the first 10 | 3 | 4 | 2 | 3.85 |
| Hepatitis A | 10 | 8 | 4 | 4 | 15.68 |
| Hepatitis B | Not among the first 10 | Not among the first 10 | 4 | 2 | 10.67 |
| Haemophilus influenzae type b (Hib) | Not among the first 10 | 1 | 3 | Not among the first 10 | 164.86 |
| Human Papillomavirus (HPV) | 3 | 2 | 1 | 1 | 11.11 |
| Influenza (Flu) | Not among the first 10 | Not among the first 10 | 3 | Not among the first 10 | 16.67 |
| Japanese encephalitis (JE) | Not among the first 10 | Not among the first 10 | Not among the first 10 | Not among the first 10 | — |
| Measles | Not among the first 10 | 4 | 3 | 1 | 34.78 |
| Meningococcal infection | 9 | Not among the first 10 | 2 | 1 | 37.29 |
| Mumps | Not among the first 10 | Not among the first 10 | 4 | Not among the first 10 | 62.96 |
| Pertussis | 6 | 3 | 1 | 1 | 1.72 |
| Pneumococcal infection | 10 | Not among the first 10 | Not among the first 10 | Not among the first 10 | 230.00 |
| Polio | 6 | 1 | 1 | 1 | 26.42 |
| Rabies | 9 | 7 | 1 | 1 | 6.85 |
| Rotavirus | 9 | 2 | 1 | 2 | 13.51 |
| Rubella | Not among the first 10 | Not among the first 10 | 2 | 1 | 2.50 |
| Shingles (Herpes Zoster) | Not among the first 10 | 1 | 5 | 1 | 3.75 |
| Smallpox | Not among the first 10 | Not among the first 10 | Not among the first 10 | Not among the first 10 | 2.04 |
| Tetanus | 2 | 1 | 2 | 1 | 7.41 |
| Typhoid fever | Not among the first 10 | Not among the first 10 | Not among the first 10 | Not among the first 10 | — |
| Typhus | Not among the first 10 | Not among the first 10 | Not among the first 10 | Not among the first 10 | — |
| Tuberculosis (TB) | Not among the first 10 | Not among the first 10 | Not among the first 10 | Not among the first 10 | 5.13 |
| Varicella (Chickenpox) | Not among the first 10 | Not among the first 10 | 3 | 1 | 4.23 |
| Yellow Fever | 6 | 2 | 1 | 1 | 5.56 |
Vaccine-related queries are generally influenced by media coverage (Table 3).
Table 3.
Vaccine-related queries in terms of interest and potential impact of the media coverage.
| Preventable infectious diseases | Interest toward vaccine | Related queries | Media influence |
|---|---|---|---|
| Anthrax | Not enough volume | Not enough volume | Not enough volume |
| Cervical Cancer (Human Papillomavirus) | Stable | Side effects (breakout); use of vaccine in men (breakout) | 10 peaks due to media coverage |
| Diphtheria | Rising | Use during pregnancy (breakout); side effects (breakout) | 4 peaks due to media coverage |
| Hepatitis A | Stable | Vaccine schedule (breakout); general information | 1 peak due to media coverage |
| Hepatitis B | Rising | Vaccine schedule (breakout); general information | 2 peaks due to media coverage |
| Haemophilus influenzae type b (Hib) | Stable | General information | 1 peak due to media coverage |
| Human Papillomavirus (HPV) | Stable | Side effects (breakout); use of vaccine in men (breakout) | 10 peaks due to media coverage |
| Influenza (Flu) | Stable | Swine flu (breakout); side effects | 6 peaks due to media coverage |
| Japanese encephalitis (JE) | Rising | General information (breakout) | 4 peaks due to media coverage |
| Measles | Stable | Side effects (breakout); link with autism (breakout); vaccine schedule (breakout); general information | 10 peaks due to media coverage |
| Meningococcal infection | Stable | General information | 6 peaks due to media coverage |
| Mumps | Rising | Side effects (breakout); link with autism (breakout); vaccine schedule (breakout); general information | 10 peaks due to media coverage |
| Pertussis | Rising | General information (breakout); use during the pregnancy (breakout) | 4 peaks due to media coverage |
| Pneumococcal infection | Stable | Vaccine schedule (breakout) | 4 peaks due to media coverage |
| Polio | Rising | Use during pregnancy (breakout); side effects (breakout) | 1 peak due to media coverage |
| Rabies | Rising | Veterinary use (breakout) | 1 peak due to media coverage |
| Rotavirus | Rising | General information (breakout); vaccine schedule (breakout) | 6 peaks due to media coverage |
| Rubella | Stable | Side effects (breakout); link with autism (breakout); vaccine schedule (breakout); general information | 10 peaks due to media coverage |
| Shingles (Herpes Zoster) | Rising | Age (breakout); cost (breakout) | 6 peaks due to media coverage |
| Smallpox | Not enough volume | Not enough volume | |
| Tetanus | Rising | Use during pregnancy (breakout); side effects (breakout) | 4 peaks due to media coverage |
| Typhoid fever | None | None | 2 peaks due to media coverage |
| Typhus | None | None | 2 peaks due to media coverage |
| Tuberculosis (TB) | Rising | Side effects (breakout) | 3 peaks due to media coverage |
| Varicella (Chickenpox) | Rising | Disease symptoms (breakout); vaccine schedule (breakout) | 3 peaks due to media coverage |
| Yellow Fever | Rising | General information (breakout) | Not enough volume |
However, the interest for vaccines is increasing throughout time: in particular, users seek information about possible vaccine-related side-effects (Table 3). The five most searched vaccines are those against 1) influenza; 2) meningitis; 3) diphtheria, pertussis (whooping cough), and tetanus; 4) yellow fever; and 5) chickenpox.
Discussion
Our finding that approximately one third of the health-related queries regards vaccines is in agreement with the result obtained by Bianco et al.36 The query volumes considerably vary according to the searched vaccine.
This research has shown great interest for vaccination against HPV. This is in agreement with data from the literature, that indicate that most users are female adolescents. Also searching if it safe or not to uptake vaccines during pregnancy confirms the previous finding.
Another interesting observation is that users often search for vaccines-related side-effects. This is in agreement with what found by a Dutch study7 and, more generally, with other studies concerning drugs.37,38 This underlines the importance of properly communicating the risks that may be related to a vaccination, even though rare. ICTs can play a role also regarding this aspect. Vaxtracker, for example, is a web-based platform for the adverse events.39
This study has some limitations. GT only captures the search behavior of a certain segment of the population – those with Internet access and those using Google rather than other search engines (although Google is the most common search engine). However, the major limitation of GT is the lack of detailed information on the method by which Google generates this search data and the algorithms it employs to analyze it.
Another limitation of the current study is that we cannot speculate about a putative relationship between mandatory vaccination policies and public interest for vaccines, in that these policies differ greatly among different countries.45 This issue could be properly addressed only at single country level.
Finally, although some privacy issues exist in using Google Web search data, tracing individuals that conduct online searches when signed into their accounts and recording and analyzing data about users' characteristics, such as gender and age, intent of web search and “search outcomes” could improve the usefulness of this tool for public health and health education purposes.
Conclusion
ICTs can have a positive influence on parental vaccine-related knowledge, attitudes, beliefs and vaccination willingness, but can also lead to misinformation and vaccine concerns and problematization. As such, the web should be monitored and exploited by health-care workers working in the field of Public Health.
GT can be used for monitoring the public interest for vaccinations and explore the main information searched. This knowledge could help health-care workers in properly addressing people's concerns and doubts about vaccinations.
Material and methods
Google Trends (GT), an online tracking system of Internet hit-search volumes that recently merged with its sister project Google Insights for Search (Google Inc.), was used to explore Internet activity related to the currently preventable infectious diseases and respective, available vaccines.
GT has been extensively used in the field of infectious diseases, both for monitoring and surveillance purposes40-43 and for investigating the public interest for epidemic outbreaks, especially in terms of reaction to media coverage.44,45
Searches can be performed using “search term” or “search topic” option. The first strategy enables to search exactly what entered by the user, while in the second search approach, GT enables to search all websites not only including that given keyword but related to the entered term. We focused our analysis on the “Related Searches” section, which shows queries (and not keywords) that are related to the entered terms (which are instead true keywords). In particular, GT distinguishes between top and rising queries. Top queries are the most popular or “evergreen” queries within the used search parameters, and, as such, tend to stay relatively consistent across time periods. On the contrary, rising queries tend to increase in term of relative interest. This rise in interest is expressed in percentage; with the term “breakout,” GT indicates an increase above 5,000%.
The list of infectious diseases currently preventable with vaccines was downloaded from the US Centers for Disease Control and Prevention (CDC) and systematically searched on GT.
Disclosure of potential conflicts of interest
No potential conflicts of interest were disclosed.
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