Keith J Petrie and Kate Faasse: Monitoring public anxiety about flu

Greater monitoring of the web could provide a guide to public anxiety about flu outbreaks and social media could be used more intensively to provide relevant public health information to younger groups.

Swine flu or influenza A/H1N1 caught world media attention from April 22 2009. Newspapers stories and headlines portrayed A/H1N1 as a potential pandemic and possible world wide killer. A headline in the Daily Mail read “Could Britain cope with a pandemic? Lack of preparation ‘could leave a million dead’.” Television news reports showed closure of schools, workplaces and public events in Mexico and images of people wearing face masks as new cases spread across the globe.

The A/H1N1 outbreak also caused an escalation of activity on social networking and web searches. Twitter, the new microblogging website which allows users to post messages of 140 characters or less (“tweets”), showed an increase from virtually zero at the beginning of April to more than 125,000 tweets per day containing the term “swine flu” on May 1. Swine flu tweets then dropped away over the next week to less than 10,000 per day and a month after the peak this had dropped further to less than 2,500 a day. Similarly, BlogPulse, a search engine that monitors daily activity on web blogs, also showed a large increase in the percentage of blogs mentioning swine flu or A/H1N1 following reports of the Mexican outbreak and a further rise on May 21 when some US schools were closed and the virus was confirmed in Japan (see Figure 1).

Figure 1: Swine flu and A/H1N1 references in recent web blogs


The web has become an important source of health information as well as a medium for expressing health worries. While in the case of seasonal flu, Google search terms such as “flu remedy” and “antiviral medication” have been found to reliably coincide with regional seasonal influenza outbreaks, the recent rise in Google searches for “swine flu” seems to reflect public anxiety about the illness rather than reflecting the number of reported swine flu infections (see Figure 2). As well as gathering information, people are also using the web to post and discuss their concerns about the illness. For example, there are now over 500 groups on the social networking site Facebook discussing swine flu.

Figure 2: Numbers of recent Google searches of “swine flu” and confirmed cumulative total cases of influenza A/H1N1


Health-related activity on the web has become a marker of interest, but more importantly, public anxiety about specific illnesses. Several web applications are available to track trends using search terms, tweets, blog posts and web discussions.,,,, and all monitor how often various phrases and topics appear on the internet. These tools offer the opportunity to gather information on public web activity about a specific illness as well the types of information people are searching for or exchanging.

There are likely to be negative effects from information posted on the web during health scares that need further study. Panic and fear about an illness can cause others reading web posts to interpret benign symptoms as signs of the illness in a similar process to medical students’ disease. Thus transmission of “symptoms” may occur across electronic networks rather than through direct person to person contact. This can lead to increases in the demand for health services. For example, NHS Direct had over 1000 calls over a 24 hour period around the end of April concerning A/H1N1 with over 200 people concerned about symptoms following recent travel. Also the NZ government has recently increased the order for seasonal flu vaccines by 23% to cater for increased demand from patients following the A/H1N1 outbreak.

In the case of the A/H1N1 outbreak, web communication and social networking sites are a useful method of monitoring public concern and also communicating public health information to the younger age group that seem to be at highest risk of contracting the virus. While the web is being used more as source of health information generally, this is particular so for younger groups. Younger people are also more likely to get their news from web sources rather than through television, radio and printed media. Some progress has been made in this area, for example, CDC has a Twitter account dedicated to transmit up-to-date swine flu information ( However, greater monitoring of the web could provide a guide to public anxiety about flu outbreaks and social media could be used more intensively to provide relevant public health information, particularly to younger groups.

Keith J Petrie is a professor at the Department of Psychological Medicine, University of Auckland
Kate Faasse is a graduate student at the Department of Psychological Medicine, University of Auckland