Measuring vaccine confidence

The Lancet Infectious Diseases
Jul 2013  Volume 13  Number 7   p559 – 638

Inoculating communities against vaccine scare stories
Natasha Sarah Crowcroft, Kwame Julius McKenzie
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The biggest threat facing the success of immunisation might be public lack of confidence in vaccines, repeatedly undermined by safety concerns promulgated in social and news media.1 In The Lancet Infectious Diseases, Heidi Larson and colleagues’ study examines how a typology of concerns can be applied within an established global surveillance system, HealthMap, to track and characterise vaccine news stories.2,3 The usefulness of systematically tracking online media stories was first established for disease surveillance through a Canadian project, the Global Public Health Information Network,4 followed by several other systems including HealthMap.

Measuring vaccine confidence: analysis of data obtained by a media surveillance system used to analyse public concerns about vaccines
Heidi J Larson, David MD Smith, Pauline Paterson, Melissa Cumming, Elisabeth Eckersberger, Clark C Freifeld, Isaac Ghinai, Caitlin Jarrett, Louisa Paushter, John S Brownstein, Lawrence C Madoff

The intensity, spread, and effects of public opinion about vaccines are growing as new modes of communication speed up information sharing, contributing to vaccine hesitancy, refusals, and disease outbreaks. We aimed to develop a new application of existing surveillance systems to detect and characterise early signs of vaccine issues. We also aimed to develop a typology of concerns and a way to assess the priority of each concern.

Following preliminary research by The Vaccine Confidence Project, media reports (eg, online articles, blogs, government reports) were obtained using the HealthMap automated data collection system, adapted to monitor online reports about vaccines, vaccination programmes, and vaccine-preventable diseases. Any reports that did not meet the inclusion criteria—any reference to a human vaccine or vaccination campaign or programme that was accessible online—were removed from analysis. Reports were manually analysed for content and categorised by concerns, vaccine, disease, location, and source of report, and overall positive or negative sentiment towards vaccines. They were then given a priority level depending on the seriousness of the reported event and time of event occurrence. We used descriptive statistics to analyse the data collected during a period of 1 year, after refinements to the search terms and processes had been made.

We analysed data from 10 380 reports (from 144 countries) obtained between May 1, 2011, and April 30, 2012. 7171 (69%) contained positive or neutral content and 3209 (31%) contained negative content. Of the negative reports, 1977 (24%) were associated with impacts on vaccine programmes and disease outbreaks; 1726 (21%) with beliefs, awareness, and perceptions; 1371 (16%) with vaccine safety; and 1336 (16%) with vaccine delivery programmes. We were able to disaggregate the data by country and vaccine type, and monitor evolution of events over time and location in specific regions where vaccine concerns were high.

Real-time monitoring and analysis of vaccine concerns over time and location could help immunisation programmes to tailor more effective and timely strategies to address specific public concerns.

Bill & Melinda Gates Foundation.