In a new Washington Post and ABC News poll, more than half of unvaccinated respondents said they "probably" or "definitely" would not get a Covid-19 vaccine.

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What the poll found on vaccine hesitancy, vaccine passports, and more

The poll of 1,007 adults was conducted between April 18 and 21—during the period when the distribution of one prominent Covid-19 vaccine, manufactured by Johnson & Johnson, was temporarily paused while regulators examined potential safety concerns. (Distribution of that vaccine has since resumed.)

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The poll found that 56% of respondents had received at least one dose of a Covid-19 vaccine. But among the 44% who had yet to be vaccinated, 55% said they would either "probably" or "definitely" not get the vaccine, while just 41% said they would.

The poll also found stark differences in willingness to receive a Covid-19 vaccine by political party affiliation. For example, among all respondents, the poll found that 55% of Republicans under the age of 40 said they would not get a Covid-19 vaccine. By comparison, just 14% of Democrats under 40 said the same.

The poll also found that 55% of U.S. adults said they would support their state issuing printed or digital certificates verifying a person's vaccination, a type of documentation sometime referred to as a "vaccine passport." However, while 77% of Democrats said they supported vaccine passports, just 30% of Republicans said the same.

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The poll identified a similar partisan split in attitudes toward the possibility of businesses requiring that employees be vaccinated to come into work. Although about 45% of respondents overall supported such requirements, about 65% of Democrats supported them, compared to 22% of Republicans.

Fauci says Americans could see turnaround in the epidemic 'within a few weeks'

Meanwhile, in a virtual event hosted by the Harvard T.H. Chan School of Public Health on Monday, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and chief medical advisor for the White House, said that if the United States continues at its current vaccination pace, "literally within a few weeks, we're going to start to see a turning around of the dynamics" of the Covid-19 epidemic.

"Not down to no infections," he said. "If you're waiting for classic measles-like herd immunity, that's going to be a while before we get there. But that doesn't mean we're not going to have a significant diminution in the number of infections per day and a significant diminution in all of the parameters, namely hospitalizations and deaths."

Fauci has previously said between 70% and 85% of the U.S. population needs to be vaccinated to achieve herd immunity. On Monday, however, Fauci said herd immunity is a "moving target" and that the country should instead be focused on vaccinating as many people as possible.

"We don't know what the durability of the infection-induced immunity is," he said. "We don't know if someone who got infected last winter or in the early part of 2020 is going to be safe from a protected standpoint now" (Goldstein/Clement, Washington Post, 4/26; Cunningham, Washington Post, 4/26; Lovelace, CNBC, 4/26).