Experts are turning their focus in the fight against Covid-19 to vaccinating young Americans -- warning that even though they don't face a high chance of serious illness, they still risk long-term symptoms if they get coronavirus.
The United States has so far made significant progress in vaccinating adults. At least 25 states, plus Washington, DC, have now fully vaccinated at least half of their adult residents, data published Sunday by the CDC shows.
FOX 55: Tracking the COVID-19 Vaccine
But many experts have identified young Americans as a critical age group for inoculation success -- the key to getting the pandemic under control in the country.
People 24 and younger are getting vaccine doses at much lower rates. Among those 12 to 15, only 1.4% have received at least one dose, while 1.7% of 16- to 17-year-olds have and 7.6% of 18- to 24-year-olds have, according to data from the CDC.
To reach the threshold of protection needed to limit the virus' spread, at least 70% to 85% of the US population will need to be immunized through vaccines or infection, health experts say.
Not only could vaccinating children, teens and young adults help reach that percentage, but leaving them unvaccinated could give the virus a chance to spread, mutate and develop a strain resistant to existing vaccines.
While vaccinated people seem to be protected against current strains, "there may be future variants for which we are not so lucky," said Dr. Megan Ranney, an emergency physician and director of the Brown-Lifespan Center for Digital Health.
The stable of vaccines available to adolescents could expand soon. Moderna announced Tuesday that its two-dose Covid-19 vaccine is safe and appears to be effective in kids ages 12 to 17. It plans to submit trial results to the US Food and Drug Administration in early June, along with a request for authorization to use the vaccine among children that age, the company said.
Pfizer/BioNTech's two-dose coronavirus vaccine was authorized May 11 for children ages 12 to 15.
For young Americans who feel hesitant or even unmotivated to get vaccinated, Dr. Anthony Fauci warned that even mild Covid-19 illness can result in life-disrupting impacts.
"There's a syndrome that is referred to as long Covid, which means that you get a syndrome following the clearing of the virus where it could be for months," the director of the National Institute for Allergy and Infectious Diseases said Monday at a town hall, adding that possible persisting symptoms include profound fatigue, muscle aches, temperature dysregulation and an inability to focus.
About 1 in 5 people between ages 18 and 34 who are infected with Covid-19 reported lingering symptoms beyond two or three weeks, according to a study last year by the US for Disease Control and Prevention.
And adolescents and children still deserve protection against their risk -- however small -- of contracting a serious illness, Fauci said.
Protecting students returning for school in the fall
Protection for school-aged adolescents has increasingly come into focus as officials look ahead to the new school year.
New York Governor Andrew Cuomo said Monday children should be back in school full-time in-person statewide in September. His statement came after New York City Mayor Bill de Blasio announced that there will be no remote option for the city's public schools in the fall.
Currently, only students 12 years old and older are eligible for vaccines, though studies are underway on vaccinating younger children.
When New York City does open its public schools on September 13, students will still have to wear face masks and adhere to social distancing guidelines, NYC Schools Chancellor Meisha Porter said Monday.
"We would never take any risks with our most important assets ... our children," Porter said, adding that every school will be equipped with social and emotional support resources for students.
In California, the Los Angeles Unified School District announced that school campuses will reopen for in-person learning five days a week in the fall. Superintendent Austin Beutner recognized that not all families in the district will be ready to send their students back by then.
"We expect the vast majority of students, teachers and staff to be at school every day, but recognize that we must provide the online opportunity for those who need it," he said.
Understanding the origin of the virus could help mitigate another pandemic
Understanding how coronavirus developed could have an impact on officials' ability to respond to future pandemics, but debate around its origin has grown.
After a US intelligence report found that several researchers at China's Wuhan Institute of Virology fell ill in November 2019, a former commissioner of the US Food and Drug Administration said on Monday that there is "growing circumstantial evidence" that Covid-19 may have come from a lab.
Chinese Foreign Ministry spokesman Zhao Lijian on Monday refuted the report and accused the US of "hyping up the lab leak theory."
"Through field visits and in-depth visits in China, the experts unanimously agreed that the allegation of lab leaking is extremely unlikely," Zhao said.
"I think the challenge right now is that the side of the ledger that supports the thesis that this came from a zoonotic source, from an animal source, hasn't budged," Dr. Scott Gottlieb said on CNBC's "Squawk Box." "And the side of the ledger that suggests this could have come out of a lab has been continuing to grow,"
Whether the virus derived from an animal or a lab, it is important for health experts to know, CNN Medical Analyst Dr. Leana Wen said.
"We need to understand what the origin is, if there is in fact an intermediary animal between bats and humans we need to understand because there may be a reservoir of disease we should be looking for," Wen said. "If this is indeed a lab leak, we should also understand for the purposes of securing lab safety protocols."
Among the unanswered questions are how seriously the researchers fell ill, when they got sick and if the virus was already circulating before then, Wen said.
The Chinese government has not been transparent on this issue, she said, but it is important the global community get down to the bottom of it.
"This is not the last pandemic that we are going to see and understanding the origin of this will help us to prevent something like this from happening in the future," she said.