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Introducing computing and IT
Introducing computing and IT

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4.4 Explicit recommendations

Of the 84 websites examined, 17.9% recommended vaccination, 4.8% discouraged vaccination, while the majority (77.4%) made no recommendation either way. However, there were significant differences between the number of recommendations made by performing different types of search (Table 1).

Table 1 Percentages of sites making recommendations for or against childhood vaccination with differing search terms
Search term used Recommend vaccination (%) Discourage vaccination (%)
Negative 17.9 10.7
Neutral 25.9 3.7
Positive 10.3 0.0
(Ruiz and Bell, 2014)

Activity 11 (exploratory) Analysing search results for vaccination

  • a.Which search terms are least likely to (i) recommend vaccination and (ii) discourage vaccination?
  • b.How much more likely is a user to encounter a recommendation against vaccination when searching with negative search terms than with a neutral search term?


  • a.In both cases, positive searches produce the fewest explicit recommendations or discouragements.
  • b.Users were 10.7 / 3.7 = 2.89 times more likely to see a recommendation against vaccination than if they used a neutral term. Had they used a positive term, users would not have seen any sites discouraging vaccination.

This study demonstrated that the reliability of search engine results can be influenced by the choice of search terms used. In the case of vaccination, the wrong search terms can lead to people following incorrect health advice and being exposed to greater levels of concern and worry about the effects of childhood vaccination.

At first reading, the fact that users entering positive search terms encountered fewer myths appears to be good news. However, where a positive search returned a myth such as Children’s vaccines contain harmful chemicals, the page was unlikely to counter the myth with factual information. Overall, positive searches were relatively unhelpful to parents who were worried about falsehoods surrounding vaccination. Instead, parents could only research these myths by negative searches, which returned less accurate, potentially harmful, information. The study’s authors strongly suggest that websites offering accurate information about vaccination must include information about myths and why they are false.


In the UK, the NHS has a comprehensive page [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] listing the facts and myths about childhood vaccination.

A second weakness of positive searches was that they were least likely to return pages recommending vaccination. The authors of the study suggest that the creators of positive pages knew the benefits of vaccination and assumed their potential audience were of a similar mind, when in fact this does not seem to be the case. The researchers recommend that site developers test their pages with differing search terms to ensure that factual information always appears high in search engine results.