Biden gets COVID-19 vaccine.
  • The US is running out of people willing to get a Covid-19 shot, a leading nonprofit warned.
  • This could mean the US falls short of herd immunity, the Kaiser Family Foundation said.
  • Some states are already closing mass vaccine sites because of dwindling demand.
  • For more stories visit Business Insider.

The US may fall short of vaccinating enough people to stop coronavirus spreading in communities because not enough Americans are willing to get a Covid-19 shot, the Kaiser Family Foundation (KFF), a leading health nonprofit, warned Tuesday.

The nation's ample vaccine supply will outstrip "vaccine enthusiasm" within two to four weeks, the KFF said. Exact timing in each state could differ, it said.

Experts have estimated that about 70% of people need to be immunized to reach herd immunity, the threshold at which the virus can no longer easily spread. This could be difficult if Americans stop coming forward to get a Covid-19 shot, the KFF said.

Michael Fraser, the executive director of the Association of State and Territorial Health Officials, told The New York Times that some states felt they had already hit a wall.

"The folks that wanted it have found it. The folks that don't want it are not bothering to find it," he said.

Some mass vaccination sites are even shutting down because of dwindling demand, Forbes reported. These included three sites in Florida that were operating at less than half capacity and would be shut down in favor of mobile sites, per the Palm Beach Post.

Officials are also closing down sites in Georgia, North Carolina, and Wisconsin, among other states, and a planned mass vaccine clinic in Ohio was canceled this week because of "decreased demand," Forbes reported.

It comes as President Joe Biden is expected to announce later Thursday that the US has met his vaccination goal of 200 million shots before his 100th day in office, which is April 30. More than 51.5% of over-18s have had at least one shot, according to the Centers for Disease Control and Prevention (CDC).

The KFF said that one-fifth of Americans have consistently said they won't get vaccinated.

But the KFF said that, over time, people could move from the "wait and see" group to the "vaccine enthusiasm" group. Those on the fence were the people the White House should target, it said.

On Monday, the White House launched a media campaign to tackle vaccine hesitancy, including among younger people.

Biden said Wednesday that the state would pay for sick days to help people recover from vaccine side effects. He also reaffirmed his commitment to a tax credit for small businesses designed to offset the cost of people taking a day off to get vaccinated.

"If we let up now and stop being vigilant," he warned, "this virus will erase the progress we have already achieved."

In Mississippi, where Insider's Ralph Eubanks wrote about government distrust fueling vaccine hesitancy, less than a third of people have had at least one dose of Covid-19 vaccine. By comparison, two-thirds of people in New Hampshire have had a single shot.

"It's really going to be all about the ground game," Dr. Bechara Choucair, the White House vaccinations coordinator said, per the NYT. "It's going to be about county by county, ZIP code by ZIP code."

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