(CNN) -- While hopes of vaccinating 20 million people by New Year's Day sputtered out, the US now faces staggering new challenges in the fight against Covid-19.
Over the past week, the US has averaged 2,637 coronavirus deaths every day, according to Johns Hopkins University.
That's an average of one Covid-19 death every 33 seconds.
December was actually the deadliest month yet of this pandemic, with 77,572 lives lost.
And deaths are likely to accelerate as new infections and hospitalizations rise.
On Sunday, more people were hospitalized with Covid-19 than any other day in this pandemic -- 125,544, according to the Covid Tracking Project.
The US averaged 213,437 new infections every day over the past week, largely fueled by holiday gatherings, health experts say.
That number will likely keep rising, as the Transportation Security Administration said it screened more than 1.3 million travelers Sunday -- a new record for this pandemic.
But while daily new infections soared 16% over the past week, testing has actually decreased 11.65% over the past week, according to the Covid Tracking Project.
Doctors now worry this rampant spread of Covid-19 will push more hospitals beyond capacity and lead to more deaths as the vaccine rollout staggers along.
The possibility of giving half-doses of a vaccine
More than 4.2 million people have received their first doses of Covid-19 vaccines. But that's far behind what officials had hoped for by now. And it means herd immunity is still many months away.
To help expedite vaccinations, the US might start giving half-doses of Moderna's Covid-19 vaccine to people age 18 to 55, which could make the vaccine available to twice as many people in that age group, said Moncef Slaoui, chief scientific adviser of the federal Operation Warp Speed vaccination effort.
The US Food and Drug Administration will meet this week to consider that possibility, Slaoui said.
The decision to cut the current 100-microgram dose in half, with another half-dose 28 days later, is ultimately up to the FDA, Slaoui told CNN Chief Medical Correspondent Dr. Sanjay Gupta.
Binding and neutralizing antibody responses were similar among participants under age 55 who received either 100-microgram or 50-microgram doses, Slaoui said, citing earlier data.
While an FDA briefing document last month also mentions these "comparable" immune responses from Moderna's study, the full data has not yet been published.
Slaoui said he's "not sure it holds for Pfizer," whose vaccine dose is 30 micrograms, noting that conversation has yet to happen. Similar to the Moderna vaccine, the Pfizer/BioNTech vaccine is intended to come in two doses, spaced several weeks apart.
CNN has reached out to Moderna and Pfizer for comment.
Not everyone likes the notion of cutting vaccine doses in half.
"I don't agree with that idea," said Dr. Jonathan Reiner, a professor of medicine at George Washington University.
"We have about 13 million doses that have been shipped out to the states, and only barely 4 million doses that have gone into arms. So the bottleneck is not the lack of availability of vaccine. The bottleneck is actually the logistics of vaccinating people in this country."
It's difficult enough to get some patients on board with getting a vaccine, he said. Going against the recommended dosing could hurt patients' confidence.
"When I see people in clinic, I talk about the vaccine every single day. I'm trying to reduce vaccine hesitancy," Reiner said Monday.
"And the strongest weapon I have is the data. I can tell people that these two vaccines have been studied in 70,000 people -- more than 70,000 people -- in this two-dose strategy. And when given that way, they're both 95% effective, and basically no one gets critically ill if you get this vaccine. ... Once you break from the data, I can no longer say that."
Ideas for speeding up vaccinations
It's critical to get vaccines into people's arms soon, especially as a highly contagious strain first detected in the UK is now spreading in the US, former FDA Commissioner Dr. Scott Gottlieb said.
"New variants of the virus that appear more contagious increase the urgency to deploy the vaccine as fast as possible," Gottlieb wrote in a Wall Street Journal op-ed published Sunday.
He offered three ideas for speeding up Covid-19 vaccinations across the US:
"First, the government needs to ship more inventory," Gottlieb wrote. "Right now, the feds are holding back up to 55% of doses. The idea is to make sure there is supply to give everyone a second dose, within three weeks for Pfizer and four weeks for Moderna.
"Second, the distribution system needs improvement," he said. "National pharmacy chains like CVS and Walgreens have an agreement with the federal government to provide vaccines to long-term care facilities. The government should expand this program to help vaccinate all Americans."
Third, Gottlieb wrote, "The demand for vaccines may not align with those who are eligible ... Essential workers may stand to benefit a lot, but what if there's more demand among those over 65? If stockpiles continue to build, eligibility should be expanded."
'A rough start to 2021'
On Sunday, five states reported their highest number of new infections ever in one day -- Arizona, New Hampshire, Oklahoma, South Carolina and Washington.
And over the past week, at least five states have average test positivity rates higher than 40% -- meaning more than 40% of people who take a Covid-19 test get a positive result.
Those states include Idaho (57%), Alabama (46.7%), Iowa (44.6%), Pennsylvania: (44%) and South Dakota (43.8%). For perspective, the WHO has recommended governments not reopen until the test positivity rates stays at or below 5% for 14 days.
In South Carolina, which had a 29.6% test positivity rate Sunday, officials in four counties said their hospitals were at 100% capacity, according to the South Carolina Department of Health and Environmental Control.
"We're in for a bit of a rough start to 2021," said Maria Van Kerkhove, the World Health Organization's technical lead for Covid-19 response.
But it's possible daily life in the US could be closer to normal by the summer or fall, she said. Other countries are already well on their way -- thanks to quarantining, testing, isolation and contact tracing.
"We've seen countries bring this virus to its knees, without vaccination," Van Kerkhove said. "We have the tools at hand right now to actually bring this virus under control."
Covid-19 hospitalizations impact other families, too
The massive surge of Covid-19 has led to medical worker shortages, insufficient hospital space, postponed surgeries and reduced care for some patients.
Even families that don't have coronavirus are feeling the impact.
US Surgeon General Jerome Adams said his wife Lacey was hospitalized due to complications from her cancer treatment. But he wasn't able to see her because of Covid-19.
"I want people to understand that if you don't take precautions against Covid because you don't feel at risk, it can impact you, your family, your community in so many other ways," Adams said.
"I, as the surgeon general of the United States, had to drop my wife off at the front door and couldn't see her go in to the hospital, hadn't been able to visit her, didn't know if she was going to have a hospital bed because of all of the Covid precautions."
Adams urged Americans -- especially those who gathered over the holidays -- to self-quarantine, get tested, wear a mask, wash their hands and watch their distance.
"The projections are pretty scary, but they're projections, and what we do now matters," Adams said.
"I want people to understand that if we get over this current surge, then things will start to get better. But it depends on the actions that we all take right now."
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