The results of a new poll show that vaccine hesitancy worldwide poses a risk to ending the COVID-19 pandemic for good.
In 79 out of 117 countries surveyed, the number of people who said they were willing to be vaccinated was below 70%, the minimum percentage of the population that scientists say needs to have immunity to stop the virus from circulating.
Attitudes shift when vaccines arrive, though, experts note, and many of the countries have not begun mass vaccinations yet.
But the numbers "give a glimpse of just how strong the headwinds are in some of these places," said Julie Ray, managing editor for world news at polling company Gallup, which conducted the survey.
Gallup contacted about 1,000 people in each of the 117 countries, mostly late last year.
In 20 countries, most polled said they would not be vaccinated. In Russia, for example, 61% of people said they would refuse a vaccine; in Kosovo, 56% would refuse; and in Senegal, 55%.
Overall, based on the results, the survey estimates that more than 1 billion people of the 7.6 billion worldwide would not get vaccinated.
Health officials are aiming to get enough people vaccinated to reach "herd immunity," a state in which the spread of the disease slows dramatically because the virus has a hard time finding new people to infect.
The more the virus circulates, the more opportunity it has to mutate into dangerous new variants that can undermine vaccines.
Scientists do not know exactly when a population reaches herd immunity, but the best estimate, often cited, is when 70% to 90% have protection.
In total, 68% of people surveyed said they would be vaccinated, just short of the lowest end of the threshold.
"It's a big deal," Ray said.
Vaccination is not the only factor in herd immunity. Natural infections also contribute. Some countries in which vaccine rollout is under way are seeing sharp declines in cases long before vaccines reach 70% of the population.
But questions remain about the strength of the immune response to natural infection, its length and whether emerging variants can overcome it. Many of these questions remain unanswered concerning the COVID-19 vaccines as well.
The 'moveable middle'
The survey was conducted before vaccines began to roll out anywhere. Attitudes have probably shifted somewhat already, Ray said, as hundreds of millions of shots have been given and media coverage has been widespread.
The United States is a good example of how opinions change once vaccination starts. But it also shows the limits of how much can change.
Gallup conducted the U.S. portion of the global poll between August and October. At the time, about 46% of Americans said they would not be vaccinated.
Gallup's most recent survey, in March, shows that figure has fallen to 26%.
The biggest change, according to a separate poll, was among people who said they would "wait and see" whether they would get vaccinated.
According to the Kaiser Family Foundation COVID-19 Vaccine Monitor, in December, nearly 2 in 5 people said they would wait and see, while only 1 in 3 said they would get a vaccine as soon as possible.
By March, the "wait and see" group had shrunk to 17%, while more than half said that they had already gotten their shots or would as soon as possible.
Outright refusals did not change much, on the other hand, decreasing from 15% in December to 13% in March.
"We focus on this movable middle," said behavioral scientist Rupali Limaye with the International Vaccine Access Center at the John Hopkins Bloomberg School of Public Health.
She said in every country, some people are ready to roll up their sleeves right away and some are dead set against it. But "a huge proportion of the population ... is just ambivalent (about vaccines), meaning they need a nudge in one direction or the other."
In some countries, people are hesitant because they do not trust the government, Gallup's Ray said.
Trust in government is low in the countries of the former Soviet Union, for example, and residents were far less likely to say that they would take the vaccine.
But that is not the whole story, she added. Among Russians who were confident in their government, 49% still said that they would not take it.
Some of the reluctance is about vaccines in general. Ray had worked on another poll, the 2018 Wellcome Global Monitor, that examined attitudes toward vaccines, among other things. Not surprisingly, there is a lot of overlap between those countries in which a low percentage of people in the Wellcome poll said that vaccines were safe and those countries in which a high percentage in the new survey said that they would refuse vaccines.
In Eastern Europe, for example, only 40% of people told the Wellcome poll that vaccines were safe. Ten of the 20 countries in which the majority of those polled would refuse the vaccine are in Eastern Europe.
Another factor: In Eastern Europe especially, "misinformation is through the roof," Limaye said, "which has caused another whole wrench in the plan."
Unfortunately, in much of the world, she said, "they're not getting a lot of pro-vaccine messages right now ... (because) the vaccine is not available in the vast majority of the world."
Creating demand for a product that is not available is not helpful, so "right now we're in a bit of a weird holding pattern," she said.