Measuring vaccine confidence: introducing a global vaccine confidence index

Abstract

Background: Public confidence in vaccination is vital to the success of immunisation programmes worldwide. Understanding the dynamics of vaccine confidence is therefore of great importance for global public health. Few published studies permit global comparisons of vaccination sentiments and behaviours against a common metric. This article presents the findings of a multi-country survey of confidence in vaccines and immunisation programmes in Georgia, India, Nigeria, Pakistan, and the United Kingdom (UK) - these being the first results of a larger project to map vaccine confidence globally.

Methods: Data were collected from a sample of the general population and from those with children under 5 years old against a core set of confidence questions. All surveys were conducted in the relevant local-language in Georgia, India, Nigeria, Pakistan, and the UK. We examine confidence in immunisation programmes as compared to confidence in other government health services, the relationships between confidence in the system and levels of vaccine hesitancy, reasons for vaccine hesitancy, ultimate vaccination decisions, and their variation based on country contexts and demographic factors.

Results: The numbers of respondents by country were: Georgia (n=1000); India (n=1259); Pakistan (n=2609); UK (n=2055); Nigerian households (n=12554); and Nigerian health providers (n=1272). The UK respondents with children under five years of age were more likely to hesitate to vaccinate, compared to other countries. Confidence in immunisation programmes was more closely associated with confidence in the broader health system in the UK (Spearman's ρ=0.5990), compared to Nigeria (ρ=0.5477), Pakistan (ρ=0.4491), and India (ρ=0.4240), all of which ranked confidence in immunisation programmes higher than confidence in the broader health system. Georgia had the highest rate of vaccine refusals (6 %) among those who reported initial hesitation. In all other countries surveyed most respondents who reported hesitating to vaccinate went on to receive the vaccine except in Kano state, Nigeria, where the percentage of those who ultimately refused vaccination after initially hesitating was as high as 76%) Reported reasons for hesitancy in all countries were classified under the domains of "confidence," "convenience," or "complacency," and confidence issues were found to be the primary driver of hesitancy in all countries surveyed.

Keywords: vaccine hesitancy.

Figures

"A Warning from History"

Published originally in the November 2012 Report of the Independent Monitoring Board of the Global Polio Eradication Initiative, this figure presents the spread of poliovirus from Nigeria following the 2003-2004 boycott.

Overview of Confidence Comparisons

These plots compare confidence scores for immunisation programmes against confidence scores in the larger health system, in emergency services, in family planning services, and in community health workers, in each country for which the requisite data are available.

Confidence in Immunisation Programme and Health System

These contingency tables illustrate the varying association between confidence in immunisation programmes and confidence in the broader health system in India, Pakistan, the UK, and households and providers in Nigeria.

Relationship between Vaccine Confidence and Vaccination Behavior

Probability of having hesitated to vaccinate in the past, according to expressed level of confidence in immunisation programmes, in each country for which the requisite data are available. Dotted lines indicate average hesitancy rate for RCU5s, irrespective of confidence in immunisation programmes.

Reasons for Hesitancy

These graphs illustrate the total sample size (whole circle), composed of respondents who were not parents of children under 5 (light grey slice), parents who never hesitated to vaccinate their children (medium grey slice), and hesitant parents (dark grey slice). The curved grey-and-orange dial to the right of the hesitant slice shows the proportion of hesitant parents who ultimately refused the vaccine (orange), and those who eventually went on to get the vaccine (grey). Hesitant parents are further disaggregated according to the reasons they gave for their hesitation, which are grouped into complacency (blue), confidence (magenta), convenience (green), and other (grey).

Figure 6: Perceptions of vaccine coverage This figure compares perceptions of how many people get vaccinated among those respondents without children under 5 (outer ring) to those reported by those with children under five RCU5s (inner circle).

Fig. 7: Confidence in Immunisation Programme and Emergency Services These contingency tables illustrate the varying association between confidence in immunisation programmes and confidence in emergency services in India and the UK.

Fig. 8: Confidence in Immunisation Programme and Family Planning These contingency tables illustrate the varying association between confidence in immunisation programmes and confidence in family planning programmes in India, Pakistan, and households and providers in Nigeria.

Fig. 9: Confidence in Immunisation Programme and Community Health Workers These contingency tables illustrate the varying association between confidence in immunisation programmes and confidence in community health workers in India, Pakistan, the UK, and households and providers in Nigeria.