(CNN) The surge of Covid-19 fueled by the Delta variant and low vaccination rates is sending the country backward in the pandemic, with hospitalizations reaching wintertime levels.
For the first time since February 27, more than 50,000 Covid-19 patients were hospitalized Monday, according to data from the US Department of Health and Human Services.
The 50,625 hospitalizations were more than triple the number from one month ago, when about 16,000 patients were hospitalized.
At this point, it might not be possible to reach herd immunity, the director of the National Institutes of Health said. At the current pace of vaccinations, it will take until mid-February to reach all of the remaining eligible people with at least one dose, a CNN analysis of Centers for Disease Control and Prevention data found.
"The idea that we could get actually 80% of the public completely unable to harbor this virus, maybe that's not going to be achievable with the Delta variant," NIH Director Dr. Francis Collins said Tuesday.
"But we could still get to a place where this becomes a nuisance instead of a threat to your life."
Full vaccination is the best way to mitigate the pandemic, Collins told CNN. "If you are vaccinated, your likelihood of getting infected and spreading this virus is greatly reduced," he said.
Republican Gov. Spencer Cox said he's fed up with people who can get vaccinated but choose not to.
So to help protect children too young to get vaccinated, "I have instructed our teams to provide a KN95 mask for every child that wants one in the state," Cox said Tuesday.
"We are purchasing those now. We will make those available to schools so that children and parents who want their child to be masked ... will have the opportunity to have available at no cost to them a KN95 mask."
The governor said neither he nor schools have the authority issue mask mandates, but local health departments and county elected officials can decide on a mask mandate for their schools for 30 days at a time.
Cox said the pandemic is a "pandemic of the unvaccinated," which the CDC director has also said. The governor said he's frustrated that those vaccinated against Covid-19 have to wear masks to help the unvaccinated.
"The CDC is asking all of you who are vaccinated to take one for the team once again, to protect people who are not vaccinated but who have the opportunity to do so," the governor said.
"I'm really tired, I'm really done with it. And I'm not really excited to have to sacrifice to protect someone who doesn't seem to care."
Covid-19 hospitalizations just reached a record high in Louisiana, with 2,112 people hospitalized Tuesday, the state health department said. The previous high was 2,069 on January 7.
Of those Covid-19 patients hospitalized, 89% were not vaccinated, and 222 are on ventilators, the health department said.
The ICU of Louisiana's largest hospital is stretched to its limit. As of Monday, 23 people were waiting for space to open up in the ICU, said Dr. Catherine O'Neal, chief medical officer of Our Lady of the Lake Regional Medical Center in Baton Rouge.
"You have people with chest pain sitting in an ER right now while their families sit in the waiting room. And they are wringing their hands. And they are calling everybody they know" to get into an ICU, O'Neal said.
About two weeks ago, the hospital had 36 Covid-19 patients. As of Monday, it had 155. .
"No one diagnosis should take up one quarter of your hospital," O'Neal said. "We no longer think we're giving adequate care to anybody because these are the darkest days of the pandemic."
O'Neal stressed the need for more people to get vaccinated. And because the vaccines don't fully kick in until two weeks after the final dose, she said it's important to keep wearing masks.
The Delta variant is several times more contagious than the original strain of novel coronavirus and appears to cause more severe disease, according to an internal presentation from the CDC.
While fully vaccinated people are still less likely to get infected, the CDC updated its guidance last week, saying even vaccinated people in areas with substantial or high transmission should mask up when in indoor public places.
That guidance covers more than 90% of the US population -- about 300 million people, according to a CNN analysis of CDC data published Monday.
Louisiana Gov. John Bel Edwards temporarily reinstated his state's mask mandate for all people ages 5 and older, both vaccinated and unvaccinated, in indoor public places. The mandate goes into effect Wednesday.
Wearing masks is important to help keep "our kids back in school and in-person and maintaining our growing economy by keeping businesses open," said Dr. Joseph Kanter, Louisiana's state health officer.
No one should mistake the current situation as "just another surge," Edwards said.
"We've already had three of these. This is the worst one we've had thus far," the governor said.
The current nationwide surge may be the worst yet, former US surgeon general and WISH-TV medical expert Dr. Jerome Adams said.
"We are not crying wolf here," Adams told The Washington Post. "This surge that we're going through right now has every potential to be -- and already looks to be -- the worst surge we've faced so far."
New York City will soon require proof of vaccination to enter any restaurant, fitness center or indoor entertainment venue in the city, Mayor Bill de Blasio announced Tuesday.
The policy will go into effect in the next few weeks.
Proof of vaccination can be in the form of a vaccine card, the NYC COVID SAFE app or the New York State Excelsior app, de Blasio said.
The FBI has warned forged vaccination cards could lead to legal consequences, including possible prison time.
With those under age 12 not yet able to get vaccinated, parents may want to consider wearing masks at home, Collins said. He later took to Twitter to clarify his comments, saying there's no need to mask at home, but "parents who live in communities with high COVID transmission rates should mask when out in public indoor settings to minimize risks to their unvaccinated kids."
"It's clear that this variant is capable of causing serious illness in children. You have heard those stories coming out of Louisiana pediatric ICU's where there are kids as young as a few months old who are sick from this," the director of the National Institutes of Health said.
The CDC has a list of ways parents can help keep their children safe, including:
-- Get vaccinated yourself. Covid-19 vaccines reduce the risk of people getting and spreading Covid-19.
-- If your child is 2 years or older, make sure your child wears a mask in public settings.
-- If your child is younger than 2 years or cannot wear a mask, limit visits with people who are not vaccinated or whose vaccination status is unknown. And keep distance between your child and other people in public.
The San Francisco Department of Public Health said Tuesday it will allow people vaccinated with the one-shot Johnson & Johnson Covid-19 vaccine to receive a supplemental mRNA vaccine dose. Doses will be available at Zuckerberg San Francisco General Hospital.
Health department officials said they were making an "accommodation" for those who have consulted with a physician and said it was not a recommendation or policy change.
This comes after Pfizer released data last week saying a third dose of the Pfizer/BioNTech Covid-19 vaccine can "strongly" boost protection against the Delta variant. The company plans to submit data on a third dose of its vaccine to the Food and Drug Administration, said Dr. Mikael Dolsten, who leads worldwide research, development and medical for Pfizer.
However, the decision on if and when booster shots will be necessary will be made by agencies like the FDA and CDC, according to US Surgeon General Dr. Vivek Murthy.
"This data from Pfizer, we've been in talks with them about what they're seeing with regard to their studies related to boosters," Murthy said, when asked about Pfizer's new data. "But at this point, I want to be very clear: People do not need to go out and get a booster shot."
In San Francisco, though, officials said the health department's decision to allow a supplemental dose aligns with the CDC, which does not currently recommend a booster shot for anyone, including J&J recipients.
"We are not recommending. We are accommodating requests," Dr. Naveena Bobba, deputy director of health for the department, said during a media briefing. "We have gotten a few requests based on patients talking to their physicians and that's why we are allowing for the accommodation."
When asked whether anyone can walk in and receive a supplemental mRNA vaccine dose, Bobba said that each vaccine site in the city will choose how to proceed with the accommodation, but "the expectation is that they have had a discussion with a health care provider when they come in."
Reports of infections among vaccinated people, known as breakthrough infections, have caused some concern among the public. But experts say they are not as alarming as they may seem.
"The vaccines are doing exactly what we're asking them to do when it comes to keeping you out of the hospital, out of serious disease and certainly preventing your death," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.
Vaccines provide an eightfold reduction in people getting the disease and a 25-fold reduction in both Covid-19 related hospitalizations and deaths, Fauci said.
"An important point to bring up is that the greater percentage of people that are vaccinated, even with a high degree of protection, the absolute number of breakthrough infections might appear high," he said.
"You can expect breakthrough infections. Most of these infections are going to be asymptomatic or mild."
"The bottom line of what we are saying is ... Get vaccinated," Fauci said.
Efforts are underway to expand Covid-19 testing, Fauci said Tuesday at a discussion hosted by the Center for Strategic and International Studies. Such testing is made more important by the impending flu season and the push for Covid-19 treatments, he said.
"If you get into the flu season, where people present with very similar symptomatology, then you're going to want a test that will tell you immediately, is this flu? Is this SARS-CoV-2? Or is this something else, whatever that might be. RSV, parainfluenza, rhinovirus, whatever," Fauci said.
But there's promising news in states hit hardest by this surge, White House coronavirus response coordinator Jeff Zients said.
"In the states with the highest case rates, daily vaccination rates have more than doubled," Zients said Monday.
"The eight states with the highest current case rates have seen an average increase of 171% in the number of people newly vaccinated, each day over the past three weeks," he said.
"Louisiana has seen a 302% increase in the average number of newly vaccinated per day, Mississippi 250%, Alabama 215%, and Arkansas 206%," Zients said.
"Americans are seeing the risk and impact of being unvaccinated and responding with action. And that's what it's going to take to get us out of this pandemic."