By Aya Elamroussi, CNN
(CNN) -- The US is making headway in its battle against Covid-19 -- with infection and hospitalization rates on the decline after a surge fueled by the highly transmissible Delta variant. But with the number of Americans getting booster shots surpassing those who are initiating vaccination, experts warn more is needed to continue the progress.
The country has averaged more than 101,200 new cases a day over the last week -- down 41% from a peak in a Delta-driven wave reached in mid-September, according to Johns Hopkins University data.
The number of Covid-19 patients in US hospitals -- 68,760 as of Thursday -- is down 34% from a Delta-wave peak reached in September, according to the Department of Health and Human Services.
Just over 56% of the total US population is fully vaccinated, according to the Centers for Disease Control and Prevention.
"This wave is receding, but unless we get the nearly 70 million unvaccinated Americans vaccinated, we are at risk for future waves," Dr. Tom Frieden, former head of the CDC, told CNN on Wednesday.
An average of 384,963 booster vaccine doses are being given daily, while roughly 281,303 people are getting their first dose every day and about 292,927 people are becoming fully vaccinated each day, according to Wednesday's CDC data.
Meanwhile, the number of Americans eligible for a vaccine could soon expand. Pfizer and BioNTech said Thursday they are seeking US Food and Drug Administration emergency use authorization for their Covid-19 vaccine for children ages 5 to 11.
If authorized, this would be the first Covid-19 vaccine for younger children. The Pfizer/BioNTech vaccine is approved for people age 16 and older and has an EUA for people ages 12 to 15.
An FDA vaccine advisory panel is scheduled to discuss Pfizer's request on October 26. If the FDA authorizes it, a panel of CDC vaccine advisers will meet to consider whether to recommend its use.
In New Mexico, more people are getting vaccinated, but it's not happening quickly enough to bring down Covid-19 cases, according to Dr. David Scrase, the acting health director at the state's health department.
"Our Delta curve went up pretty steeply, and it's not coming down," Scrase said. "In fact, it's plateaued."
Scrase explained he's concerned health care workers are getting exhausted.
"In the northwest (region of New Mexico) ... the hospitals are really, really, really overwhelmed," Scrase said. "I've just talked to too many people that say as soon as this curve comes down, they're stepping back from their whole health care career. They just can't do it anymore."
And with winter fast approaching, experts are reinforcing the importance of getting vaccinated against both Covid-19 and the flu because they pose a double threat to an already strained health care system.
Researchers: Covid-19 killed parents or grandparents of 140,000 US children, and minorities were hit harder
More than 140,000 US children have lost a parent or grandparent who took care of them to Covid-19, researchers at the CDC and elsewhere reported Thursday. That's about 1 in 500 US children, the researchers said.
And children from racial and ethnic minorities were far more likely to lose such a caregiver, the CDC-led team found.
National Center for Health Statistics data through June showed that children of racial and ethnic minorities accounted for 65% of those who lost a primary caregiver, while White children accounted for 35%. That's even though minorities account for just 39% of the US population.
"During 15 months of the Covid-19 pandemic, 120,630 children in the US experienced death of a primary caregiver, including parents and grandparents providing basic needs, because of Covid-19-associated death. Additionally, 22,007 children experienced death of secondary caregivers, for a total of 142,637 children losing primary or secondary caregivers," the researchers wrote in the journal Pediatrics.
Worst hit were kids in Southern border states. Hispanic children in these states accounted for anywhere between 50% and 67% of affected children.
In Southeastern states, up to 57% of affected children are Black, and in states with tribal territories, American Indian/Alaska Native children accounted for up to 55% of kids who lost a parent or other primary caregiver to Covid-19, according to the researchers.
"Beyond parents, grandparents are increasingly indispensable, often providing basic needs. In the US from 2011 to 2019, 10% of children lived with a grandparent and in 2019, 4.5 million children lived with a grandparent providing their housing. Black, Hispanic, and Asian children are twice as likely as White children to live with a grandparent," they wrote.
"Loss of parents is associated with mental health problems, shorter schooling, lower self-esteem, sexual risk behaviors, and risks of suicide, violence, sexual abuse, and exploitation," they added. "Yet, there is hope. Safe and effective vaccines can stop Covid-19-associated orphanhood and death of caregivers from negatively impacting children and families."
Immunity from Pfizer's Covid-19 vaccine wanes, studies show
The immune protection offered by two doses of Pfizer's Covid-19 vaccine drops off after two months or so, although protection against severe disease, hospitalization and death remains strong, according to two real-world studies published Wednesday.
The studies -- from Israel and Qatar and published in the New England Journal of Medicine -- support arguments that even fully vaccinated people need to maintain precautions against infection.
One study from Israel showed antibody levels wane rapidly after two doses of vaccine "especially among men, among persons 65 years of age or older, and among persons with immunosuppression."
The study also indicated that immunity for people who get vaccinated after natural Covid-19 infection lasts longer. It's especially strong for people who recovered from infection and then got vaccinated, the study found.
A second study from Qatar looked at actual infections among the highly vaccinated population of that small Gulf nation. People there mostly got Pfizer/BioNTech's vaccine.
The study found protection induced by the Pfizer vaccine "builds rapidly after the first dose, peaks in the first month after the second dose, and then gradually wanes in subsequent months," the research team wrote. "The waning appears to accelerate after the fourth month, to reach a low level of approximately 20% in subsequent months," they added.
Nonetheless, protection against hospitalization and death stayed at above 90%, researchers said.
The Pfizer vaccine is authorized by the FDA for use as a booster for people 65 and older, people at high risk of severe disease and people whose jobs put them at risk of infection.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, continued to tout the importance of vaccination Wednesday, and cautioned those hoping a promising but unapproved antiviral pill will eliminate the need for inoculation.
The drug, called Molnupiravir, was developed by Merck and Ridgeback Biotherapeutics. The companies said last week that the pill could potentially cut in half the risk of death from Covid-19, but Fauci said it needs more scrutiny before it can be considered for authorization.
"It is very important that this now must go through the usual process of careful examination of the data by the Food and Drug Administration both for effectiveness, but also for safety, because whenever you introduce a new compounds, safety is very important," Fauci said.
He also noted, it's more important to prevent disease than to treat it. "Vaccines -- they remain our best tools against Covid-19, because it is much, much better to prevent ourselves from getting infected than having to treat an infection."