Since the race to develop a coronavirus vaccine began last spring, upbeat announcements were stalked by ominous polls: No matter how encouraging the news, growing numbers of people said they would refuse to get the shot.

The time frame was dangerously accelerated, many warned. The vaccine was a scam from Big Pharma, others said. A political ploy by the Trump administration, many Democrats charged. The internet pulsed with apocalyptic predictions from longtime vaccine opponents, who decried the new shot as the epitome of every concern they'd ever put forth.

But over the past few weeks, as the vaccine went from hypothetical to reality, something happened. Fresh surveys show attitudes shifting and a clear majority of Americans now eager to get vaccinated.

In polls by Gallup, the Kaiser Family Foundation and the Pew Research Center, the portion of people saying they are now likely or certain to take the vaccine has grown from about 50% this summer to more than 60%, and in one poll 73% — a figure that approaches what some public health experts say would be sufficient for herd immunity.

Resistance to the vaccine is not vanishing. Misinformation and dire warnings are gathering force across social media. At a meeting on Dec. 20, members of an advisory panel to the Centers for Disease Control and Prevention cited strong indications that vaccine denouncements as well as acceptance are growing, so they could not predict whether the public would clamor for limited supplies or take a pass.

But the attitude change is striking. A similar shift on another heated pandemic issue was reflected in a different Kaiser poll this month. It found that nearly 75% of Americans are now wearing masks when they leave their homes.

The change reflects a constellation of recent events: the uncoupling of the vaccine from Election Day; clinical trial results showing about 95% efficacy and relatively modest side effects for the vaccines made by Pfizer-BioNTech and Moderna; and the alarming surge in new coronavirus infections and deaths.

"As soon as it is my turn to get the vaccine, I will be there front and center! I am very excited and hopeful," said Joanne Barnes, 68, a retired elementary school teacher from Fairbanks, Alaska, who told the New York Times last summer that she would not get it.

What changed her mind? "The Biden administration, returning to listening to science and the fantastic stats associated with the vaccines," she replied.

The lure of the vaccines' modest quantities also can't be underestimated as a driver of desire, somewhat like the must-have frenzy generated by a limited-edition Christmas gift, according to public opinion experts.

That sentiment can also be seen in the shifting nature of some of the skepticism. Rather than just targeting the vaccine itself, eyebrows are being raised across the political spectrum over who will get it first — which rich individuals and celebrities, demographic groups or industries?

But the grim reality of the pandemic and the wanness of this holiday season are perhaps among the biggest factors.

"More people have either been affected or infected by COVID," said Rupali Limaye, an expert on vaccine behavior at the Johns Hopkins Bloomberg School of Public Health. "They know someone who had a severe case or died."

Limaye concluded: "They are fatigued and want to get back to their normal lives."