(CNN) Covid-19 vaccination rates are down and cases are on the rise, exacerbated by the more transmissible Delta variant -- and an expert says the key to winning the race against the spread is getting more Americans vaccinated.
"We're losing time here. The Delta variant is spreading, people are dying, we can't actually just wait for things to get more rational," Dr. Francis Collins, director of the National Institutes of Health told CNN on Wednesday.
In Arkansas, the top official at the University of Arkansas for Medical Sciences sounded the alarm Thursday on current Covid-19 infection and hospitalization rates in the state.
When asked during a Q&A on Twitter about the impact the Delta variant is having on hospitalizations, Chancellor Cam Patterson said hospitals are "full right now and cases are doubling every 10 days."
"If that trend continues, there will be significant challenges in providing care for both Covid and non-Covid patients over the next two weeks," Patterson said, noting he met with Gov. Asa Hutchinson to discuss the matter.
Patterson said while hospitals have the ability to add more ICU beds, staffing is an acute issue. Patterson said they "are close to the limit now."
Vaccines have been available to most Americans for months, but still only 48.3% of the country is fully vaccinated, according to the US Centers for Disease Control and Prevention -- and the rate of new vaccinations is on the decline. It was down 11% from a week ago and is less than a quarter of the pace from two months ago.
Meanwhile, case rates have been going up dramatically. In 47 states, the rate of new cases in the past week is at least 10% higher than the previous week, according to data from Johns Hopkins University. A total of 35 states have seen increases of more than 50%.
Officials and experts have said disinformation is largely to blame for the high number of unvaccinated Americans, a group that is seeing the largest impacts of the pandemic.
"This is not just a matter of people expressing opinions that might be wrong, this is life and death," Collins said.
Much of the data now shows that more than 99% of people currently hospitalized with Covid-19 are unvaccinated, Collins said. That means those who are vaccinated have enough protection that they aren't getting severely ill, Collins said.
And the vaccines are still showing signs of being very effective against the Delta variant, he said, which is one of the greatest concerns for health experts currently.
Collins said he hopes the American public will pay attention to the data and decide that getting vaccinated is the safe and smart thing to do.
"I hope people will hear this, right now listening to this: If you are on the fence about whether vaccination is going to help you, listen to those numbers," Collins said. "Why are we waiting folks? Let's roll up our sleeves if we haven't already done so."
The United States' top doctor spoke at the White House press briefing announcing a 22-page advisory titled "Confronting Health Misinformation."
"Health misinformation has cost us lives," US Surgeon General Dr. Vivek Murthy said at a White House briefing.
Murthy urged tech companies to monitor misinformation more closely and take action against "misinformation superspreaders."
He also asked people to check sources before reposting Covid information on social media.
"If you're not sure, don't share," he said.
Murthy blamed misinformation for the slowing pace of vaccinations.
"It's one of several reasons why people are not getting vaccinated, but it's a very important one because what we know from polls ... is that two-thirds of people who are not vaccinated either believe common myths about the Covid-19 vaccine or think some of those myths might be true," Murthy said.
Experts have speculated that there may be a need for Covid-19 vaccine boosters in the future, but many have said that for now, the current vaccines appear to provide enough protection.
Pfizer said last week a booster for its vaccine could be needed six months to a year after completion of the first two vaccine doses, prompting a rare public rebuke from the CDC and the US Food and Drug Administration. The company met with administration and top public health officials this week to discuss the data.
"We don't think that boosters are needed at the current time," Acting FDA Commissioner Dr. Janet Woodcock said Wednesday.
"We will follow the data on waning of immunity over time and the data on acquisition of infections by the vaccinated to see if, at some point, it appears that a booster would be warranted," Woodcock said in a conversation hosted by STAT News.
The more important conversation at this stage, she said, is getting unvaccinated people vaccinated.
But Collins noted, for some people, an extra dose -- not a booster -- may help get their immune response to a fully vaccinated level.
"People who have immune deficiencies, who did not get a full response to the original pair of doses from Moderna or Pfizer, or the one dose from J&J -- maybe an additional dose might help those people," Collins told CNN's Erin Burnett, specifically pointing to organ transplant recipients and cancer patients on chemotherapy.
"I wouldn't call that a booster, though," Collins added. "I would just say that's trying to get the primary immunization up to the level it needs to be -- that's under consideration."