In December, Joe Biden outlined an important goal: One hundred million Americans would receive at least a single dose of a COVID-19 vaccine within the first 100 days of his presidency.

On Thursday, Biden declared that he was well ahead of schedule. “I’m proud to announce that tomorrow, 58 days into our administration, we will have met our goal,” the president said.

Tomorrow, we’re going to hit a big milestone: 100 million shots in people’s arms. pic.twitter.com/Cj65chMhJJ

— President Biden (@POTUS) March 19, 2021

Biden’s 100 doses in 100 days initiative has been criticized for lacking ambition. As NBC News points out, “In the final days of then-President Donald Trump’s administration, nearly 1 million shots were being administered per day, the daily average Biden needed to hit in order to meet his goal.”

But the milestone marks an achievement few thought was possible just a year ago, and Biden said his administration would be announcing a new goal next week.

Biden added that 65 percent of people age 65 or older had received at least one shot and 36 percent have been fully vaccinated.

However, a new Washington Post-Kaiser Family Foundation poll reveals that vaccine hesitancy exists within a surprising group: health-care workers.

According to The WaPo description of the poll:

“barely half of front-line health-care workers (52 percent) said they had received at least their first vaccine dose at the time they were surveyed. More than 1 in 3 said they were not confident vaccines were sufficiently tested for safety and effectiveness.

The nationally representative survey of 1,327 front-line health-care workers, conducted Feb. 11 through March 7, illustrates the challenges ahead as vaccine advocates try to persuade a wider population — with less familiarity with medicine — to get vaccinated.“

The Post-@KFF poll shows the importance of employers in efforts to vaccinate front-line health care workers – nearly 8 in 10 of those who said they had been vaccinated received doses from their employers. https://t.co/VHQQFTaSK4

— Post Polls (@PostPolls) March 19, 2021

Vaccine hesitancy is particularly prevalent among Republicans. According to a recent NPR/PBS NewsHour/Marist survey, nearly half of Republican men (49%) say they won’t choose to be vaccinated when they are eligible.

Earlier this week, former-President Trump, the most influential figure in GOP culture, encouraged his supporters to get vaccinated.

On Friday evening, Biden and the Vice President, Kamala Harris, are scheduled to visit the Centers for Disease Control in Atlanta to get an “update from the team of health and medical experts who are helping lead the fight against the pandemic.”

They are also expected to meet with Asian American leaders to discuss the recent uptick in violence against that community.