Public confidence in vaccines varies widely around the world, with low but improving acceptance in some areas of Europe and growing wariness in countries experiencing political instability and religious extremism, according to the largest known vaccine confidence modeling study.
The study, published yesterday in The Lancet, analyzed data from 290 nationally representative surveys of 284,381 adults in 149 countries collected from September 2015 to December 2019 on the importance, efficacy, and safety of vaccines. The data are regularly collected by the Vaccine Confidence Project at the London School of Hygiene & Tropical Medicine, which led the study.
The findings could spell trouble as officials roll out COVID-19 vaccines in the coming months once they are approved, which could be later this year or early in 2021.
Regular monitoring of vaccine attitudes is critical, the authors said, because vaccine hesitancy interferes with uptake of life-saving vaccines for infectious diseases such as COVID-19. In 2019, the World Health Organization declared vaccine skepticism one of the top 10 global health threats because it is at least partially behind a rising number of outbreaks for preventable diseases such as measles, meningitis, and polio.
Vaccine opposition, misinformation campaigns
In the survey, vaccine confidence in Europe ranged from just 19% in Lithuania to 66% in Finland in December 2019. And at least partially because of an anti-vaccine movement in Poland, vaccine confidence in that country fell from 64% in November 2018 to 53% in December 2019. But upticks have been noted in trust in vaccine safety in areas of Europe, especially in Finland, France, Italy, Ireland, and the United Kingdom.
In contrast, strong anti-vaccine sentiment has grown in six politically unstable countries affected by religious extremism, including Afghanistan (from 2% in 2015 to 3% in 2019), Azerbaijan (2% to 17%), Indonesia (1% to 3%), Nigeria (1% to 2%), Pakistan (2% to 4%), and Serbia (4% to 7%).
Vaccine confidence also dropped in Indonesia, Pakistan, the Philippines, and South Korea from November 2015 to December 2019. The study authors said that the decline in trust in the Philippines (from 82% support for the safety of vaccines in 2015 to 58% in 2019) was likely related to adverse events in children associated with the dengue vaccine Dengvaxia in the past 3 years.
In South Korea, the anti-vaccine group ANAKI (a Korean acronym for "raising children without medication") and like organizations have eroded trust in vaccines. Similarly, declines in trust in vaccine safety (from 64% to 50%), importance (75% to 50%), and effectiveness (59% to 47%) were seen in Indonesia from 2015 to 2019, which the authors partially attribute to Muslim leaders' skepticism about the safety of the MMR (measles, mumps, and rubella) vaccine. The leaders issued a fatwa (religious order) forbidding the vaccine, claiming that it contains swine-derived ingredients (Muslims do not eat pork).
The authors said that the results of this and other surveys can help focus public health efforts and resources in regions where they most need to build trust in vaccines. Coauthor Heidi Larson, PhD, of the London School of Hygiene & Tropical Medicine, said in a Lancet press release that misinformation about vaccine safety spreads quickly online and often causes larges declines in vaccination coverage. For example, in Pakistan and Nigeria, misleading information about the polio vaccine has led to outbreaks in both countries.
"Sometimes there is a genuine small risk that gets rapidly spread and amplified to appear to be a much larger risk," she said. "There are also cases where vaccine debates have been purposefully polarised, exploiting the doubting public and system weaknesses for political purposes, while waning vaccine confidence in other places may be influenced by a general distrust in government and scientific elites."
Perceptions of vaccine importance
Coauthor Clarissa Simas, MSc, of the London School of Hygiene & Tropical Medicine, said in the release that their findings suggest that confidence in the importance of vaccines—as opposed to their efficacy or safety—are most critical to vaccine uptake.
"Our findings suggest that people do not necessarily dismiss the importance of vaccinating their children even if they have doubts about how safe vaccines are," she said. "The public seem to generally understand the value of vaccines, but the scientific and public health community needs to do much better at building public trust in the safety of vaccination, particularly with the hope of a COVID-19 vaccine."
In 2019, countries and territories with the highest proportion of respondents who said that it was important for children to be vaccinated included Iraq (95%), Liberia (93%), and Senegal (92%), while those with the lowest proportion were Albania (26%), Hong Kong (36%), and Russia (34%).
Men and less-educated people tended to have lower vaccine uptake, in contrast with those who trust information from healthcare professionals over that from their social circles.
In a commentary in the same journal, Daniel Salmon, PhD, and Matthew Dudley, PhD, of Johns Hopkins University said that communications assuring the public about vaccine safety are urgently needed while the world awaits an approved vaccine against SARS-CoV-2, the virus that causes COVID-19.
"Without substantial global investment in active vaccine safety surveillance, continuous monitoring of public perceptions, and development of rapid and flexible communication strategies, there is a risk of SARS-CoV-2 vaccines never reaching their potential due to a continued inability to quickly and effectively respond to public vaccine safety concerns, real or otherwise," they wrote.