CNN  — 

The seven-day average of Covid-19 vaccines administered in the United States has dipped below 2 million per day for the first time since early March – a sign of the continued decline in demand for coronavirus immunizations.

According to data published Saturday by the US Centers for Disease Control and Prevention, the seven-day average of doses administered now sits at 1.98 million. The last time the daily average was below 2 million was March 2.

It’s an indicator that vaccinations are gradually slowing, even though the US remains far short of the levels of immunization needed to reach herd immunity.

About 113 million people, or at least a third of the population, have been fully vaccinated, per CDC data. About 45.6% of the population, or 151 million people, have received at least one dose of a vaccine. But experts like Dr. Anthony Fauci have estimated 70-85% would need to be immune to possibly reach herd immunity.

CDC Director Dr. Rochelle Walensky addressed flagging vaccine administrations earlier in the week, telling CNN the slowdown was expected.

“We knew that we would have a lot of supply by the end of April, early May,” she said, “but we also knew that this would be the time that we had people who were more hesitant, that people wouldn’t be rushing to be getting a vaccine.”

The dip in demand has already led to the closures of some mass vaccination sites, and more continue to follow suit: Officials announced Wednesday that one such site at Oakland Coliseum in California would close this month after a “rapid reduction” in vaccine appointments.

And on Thursday, Missouri Gov. Mike Parson announced the National Guard was scaling back its involvement at mass vaccination sites, citing reduced demand – though he also said the state is “in a good place on the vaccine front.”

This comes as the Biden administration set a new goal to vaccinate at least 70% of US adults with at least one dose by July 4. As of Saturday, only four states had done so: Connecticut, Hawaii, Massachusetts and Vermont.

In an interview with CNN’s Pamela Brown on Saturday, Andy Slavitt, the White House’s senior adviser for Covid-19, acknowledged vaccination rates have plateaued in some parts of the country, leaving some pockets “at risk for future outbreaks.”

“That’s where I think some of the myths around vaccines and vaccine hesitancy may have taken hold and they may be present,” he said. “So I think we need to be very patient and continue to allow people in those communities to hear from people they trust.”

“If you’re not sure if you want to get vaccinated, my advice is just, ask your doctor or ask your pharmacist what they think or ask someone you know who’s been vaccinated – and I think that will help you make a decision about whether or not you want to get vaccinated,” Slavitt added. “This is an individual decision.”

CDC director acknowledges possibility of vaccine boosters

As experts grow concerned about a possible Covid-19 surge in the winter, the CDC’s Walensky acknowledged it’s still possible seasonal vaccine boosters will be necessary.

“We want to hope for the best, and prepare for the worst,” Walensky told actress Jennifer Garner in an interview streamed on Instagram.

Researchers at the CDC are looking into whether a booster specific to variants that are already in the US will be needed as well as if protection from the virus fades over time, Walensky said.

“We are doing the studies on boosters to see if we will need them, and that is six months, one year, two years – we don’t really know,” Walensky said. “But we want to be prepared for them should we need them.”

If the US does need them, officials have processes already in place to get them out.

“The vision would be that we would do it in the same way that we do flu vaccine,” she said. “We hope we don’t have to do it every season, but we’re preparing in case we do.”

Slavitt said Saturday that data coming out next week indicates that vaccines authorized for emergency use in the US are proving effective against the Covid-19 variant spreading through India. He said that while the variant is “certainly causing more trouble,” it’s “not nearly as troublesome” as other variants.

“Americans should expect that if they’re not vaccinated, they’re going to be more exposed,” Slavitt said. “If they are vaccinated, I think they can look at these variants, and there’s going to be very good levels of protection so far.”

Expanding vaccine authorization

Meanwhile, vaccine manufacturers are preparing for the long haul.

Pfizer/BioNTech, whose vaccine currently has an emergency use authorization, announced the initiation of its application to the US Food and Drug Administration for full approval for people ages 16 and older.

This would be the first Covid-19 vaccine to be assessed for full approval from the FDA.

“We are proud of the tremendous progress we’ve made since December in delivering vaccines to millions of Americans, in collaboration with the U.S. Government,” Albert Bourla, chairman and chief executive officer of Pfizer, said in a statement. “We look forward to working with the FDA to complete this rolling submission and support their review, with the goal of securing full regulatory approval of the vaccine in the coming months.”

The FDA is already poised to authorize the company’s vaccine in children and teens ages 12 to 15 by early next week, a federal government official told CNN.

The vaccine also has been undergoing a safety and efficacy study in children ages 6 months to 11 years, and the company said it expects to submit for FDA emergency use authorization for children ages 2 to 11 in September.

CNN medical analyst Dr. Celine Gounder said “for some people, seeing a full approval from the FDA will indeed give them more confidence that these vaccines are safe and effective.”

“And it’s important to understand that the CDC and FDA will continue to do safety monitoring even after a full FDA approval,” she added. “That’s just business as usual.”

Conflict over asking about vaccination status

Health experts have hailed vaccination as the ticket back to a sense of normalcy, but officials have come up against conflicts over who can monitor vaccination decisions.

Wyoming is the latest state to prohibit state agencies from asking people whether they have been vaccinated against Covid-19.

Under a directive signed Friday by Gov. Mark Gordon, the state boards and agencies are ordered to “provide full access to state spaces and state services, regardless of a constituent’s COVID-19 vaccination status.”

“Vaccine passport programs have the potential to politicize a decision that should not be politicized,” Gordon said in a written statement. The press release notes that the governor has been vaccinated and encourages the residents of his state to voluntarily be vaccinated.

Unlike a similar order signed by the governor of Florida, the Wyoming directive is only mandatory for the state government.

However, it says local governments and private businesses “are encouraged” to follow Gordon’s directive.

Florida’s law prohibits businesses from asking whether employees or customers have been vaccinated.

The CEO of Norwegian Cruise Line Holdings Ltd. said Thursday it could cause the company to suspend Florida departures and move its ships elsewhere.

“At the end of the day, cruise ships have motors, propellers and rudders, and God forbid we can’t operate in the state of Florida for whatever reason, then there are other states that we do operate from, and we can operate from the Caribbean for a ship that otherwise would have gone to Florida,” CEO Frank Del Rio said during the company’s quarterly earnings call.

“In Florida, your personal choice regarding vaccinations will be protected and no business or government entity will be able to deny you services based on your decision,” Gov. Ron DeSantis said.

CNN’s Jessica Firger, Maggie Fox, Mallika Kallingal, Lauren Mascarenhas, Andy Rose and Naomi Thomas contributed to this report.