The number of Americans who say they would get vaccinated has increased to 60%, indicating the public is growing more confident that the Trump administration’s Operation Warp Speed will deliver a safe and effective vaccine for Covid-19, according to a new Pew Research Center survey.

Still, a majority of Americans say they would be uncomfortable being among the first to take a vaccine, and a sizable minority say they will pass on getting vaccinated. The findings come as the U.S. Food and Drug Administration conducts an emergency review of the Pfizer-BioNTech Covid vaccine today. The Moderna vaccine and others are also on deck for emergency FDA authorization

“Public confidence has grown that the research and development process will yield a safe and effective vaccine for Covid-19,” Pew reported. “Seventy-five percent have at least a fair amount of confidence in the development process today, compared with 65% who said this in September.”

Overall, 60% of Americans say they would definitely or probably get a vaccine for the coronavirus if one were available today, up from 51% who said so in September. About four in 10 (39%) say they definitely or probably would not get a coronavirus vaccine, though about half of this group, or 18% of U.S. adults, indicate it’s possible they would decide to get vaccinated once people start getting a vaccine and more information becomes available.

Yet 21% of U.S. adults are hard negatives and reported they do not intend to get vaccinated and are “pretty certain” more information will not change their mind, according to the Pew survey.

These findings come on the heels of preliminary analysis from the two separate Pfizer and Moderna clinical trials, which have produced vaccines that are over 90% effective. The FDA is expected to issue its first emergency authorization this week.

While public intent to get a vaccine and confidence in the vaccine development process are up, people are showing wariness about being the first to get the vaccine: 62% of the public said they would be uncomfortable doing it. Just 37% would be comfortable.

The new national survey by Pew Research Center, conducted November 18 to 29 among 12,648 U.S. adults, found that amid a rising number of Covid-19 cases in the U.S., the public’s outlook for the country has darkened: 71% say they think the worst of the outbreak is still to come, up from 59% who said so in June.

A number of factors come into play when Americans consider getting the vaccine:

Partisanship also plays a role in Americans’ decision-making about vaccines, Pew found. Overall, there’s a 19% gap between Democrats and Republicans. Sixty-nine percent of Democrats or those who lean Democrat say they will get a vaccination, while only 50% of Republicans and Republican leaners report that they’ll get one.

Republicans remain less likely than Democrats to see the Covid outbreak as a major threat to public health. Overall, 84% of Democrats and 43% of Republicans say the coronavirus outbreak is a major threat to the U.S. population as a whole. The partisan gap on this measure remains about as wide as at any point during the outbreak and stands in contrast to the large shares of both Republicans (83%) and Democrats (86%) who say the outbreak is a major threat to the U.S. economy, Pew reported.

Confidence in scientists remains slightly higher than before the pandemic. With scientists and their work in the spotlight, 39% of Americans say they have a great deal of confidence in scientists to act in the public’s best interest, an uptick from 35% who said this before the pandemic began. Most Americans have at least a fair amount of confidence in scientists. However, ratings of scientists are now more partisan than at any point since Pew Research Center first asked this question in 2016: 55% of Democrats now say they have a great deal of confidence in scientists, compared with just 22% of Republicans who say the same.

While six in 10 Americans say they would definitely or probably get a coronavirus vaccine if it were available today, up 9 percentage points from 51% in September, there remain sizable differences among key demographic groups, Pew reported.

Those with higher family incomes, adjusted for cost of living and household size, are more likely than those with middle or lower incomes to say they would get immunized, according to the survey.

Black Americans continue to stand out as less inclined to get vaccinated than other racial and ethnic groups: 42% would do so, compared with 63% of Hispanic and 61% of white adults. English-speaking Asian-Americans are even more likely to say they would definitely or probably get vaccinated (83%).

The coronavirus is thought to be a particular health risk for older adults, who are more likely to have complicating pre-existing conditions and weaker immune systems to combat the disease. Three-quarters of adults ages 65 and older say they would definitely or probably get vaccinated, compared with 55% of those under age 30, Pew found.

People’s views on getting a coronavirus vaccine that is not yet available to the general public remain fluid. Among the roughly four in 10 Americans who say they would not get the vaccine today, 46% say it’s possible they would do so once others start getting vaccinated and more information becomes available. Still, 53% of those not currently planning to get vaccinated (21% of all Americans) say they are pretty certain they won’t get a vaccine even with more information, the survey found.