NORTH TEXAS (CBSDFW.COM/CNN) – New estimates from the Centers for Disease Control show the Delta variant, a more transmissible and possibly more dangerous strain of coronavirus, now makes up more than half of all new COVID-19 infections in the US.

Delta accounts for 51.7% of new infections in the US, according to the CDC. The B.1.1.7, or Alpha variant, which has dominated for months, now accounts for 28.7% of cases, the CDC said.

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“If ever there was a reason to get vaccinated, this is it,” Dr. Anthony Fauci said during a Tuesday interview.

The variant poses a “significant threat,” to unvaccinated people Fauci, director of the National Institute of Allergy and Infectious Diseases, said.

The variant is not only more transmissible, it can also cause more severe disease, Fauci said.

And people in areas where the vaccination rate is low are especially at risk, health officials say.

“We’re already starting to see places with low vaccination rates starting to have relatively big spikes from the Delta variant. We’ve seen this in Arkansas, Missouri, Wyoming … those are the places where we’re going to see more hospitalizations and deaths as well, unfortunately,” said Dr. Ashish Jha, dean of the Brown University School of Public Health.

“Any time you have large outbreaks, it does become a breeding ground for potentially more variants,” Jha said.

The US is already grappling with variants that are more contagious than the original strain of novel coronavirus. They include the “stickier” Alpha (B.1.1.7) variant, which is currently the dominant strain in the US, and the even more contagious Delta (B.1.617.2) variant, which is on track to become the dominant strain in the US, the director of the US Centers for Disease Control and Prevention said.

“The more unvaccinated people there are, the more opportunities for the virus to multiply,” said Dr. William Schaffner, a professor in the Division of Infectious Diseases at Vanderbilt University Medical Center.

“When it does, it mutates, and it could throw off a variant mutation that is even more serious down the road.”

Parts of the South, Southwest and Midwest are starting to see spikes in cases, and many of those states — such as Alabama, Arkansas, Louisiana and Mississippi — are among those with the lowest rates of vaccination, according to the CDC.

States with below-average vaccination rates have almost triple the rate of new COVID-19 cases compared to states with above-average vaccination rates, according to recent data from Johns Hopkins University.

And since vaccines are highly effective but not perfect, some health experts say they will wear masks in certain places despite being fully vaccinated.

“If you’re in a low-infection, high-vaccination area, you don’t need to be wearing a mask indoors if you’re fully vaccinated,” Jha said.

But “if I were in southwest Missouri right now, I’m fully vaccinated, but I would be wearing a mask indoors.”

Israeli Analysis Vaccine May Not Be As Effective Against Delta As Thought

While many health experts have said available vaccines offer protection from variants now circulating, an analysis in Israel suggests the Pfizer/BioNTech vaccine — the one that Israel chose to inoculate its citizens with — may not be as effective as was previously found there, possibly because of the Delta variant.

The Israeli government said in a brief statement on Monday that as of June 6, the vaccine provided 64% protection against infection. In May — when the Alpha variant dominated in Israel and the Delta strain had not yet spread widely — it found that the shot was 95.3% effective against all infections.

The government added that the vaccine was now 93% effective in preventing severe disease and hospitalizations, compared to 97% reported in the medical journal The Lancet in May.

Israel didn’t release the data used in its analysis.

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Unvaccinated Young Adults Help Fuel The Spread

If there is another COVID-19 surge, unvaccinated young adults could be a big part of the problem, said Dr. Megan Ranney, associate professor of emergency medicine at Brown University.

“We’ve already seen that the highest number of infections over the past few months have been in those younger adults,” said Ranney, who’s also an emergency physician and director of the Brown-Lifespan Center for Digital Health.

“These are the people that thought they were invincible.”

As of Tuesday, only 47.5% of Americans have been fully vaccinated, according to CDC data.

More than 11,000 new COVID-19 cases have been reported every day over the past week, according to data from Johns Hopkins University. About 200 Americans are dying from COVID-19 every day.

Much of the suffering is unnecessary and preventable with vaccines, emergency physician Dr. Leana Wen said.

“We have the ability to stop Covid in its tracks,” she said.

On the other hand, all 50 states have fully vaccinated more than 60% of seniors, CDC data shows, from about 62% in Utah to 94% in Vermont.

What Could This Mean For A Return To School?

Children who are unvaccinated are still at high risk for infection, Wen said.

She said she disagreed with governors such as Texas Gov. Greg Abbott, who has banned public schools from requiring face masks.

“These governors that have said that schools no longer need masks indoors, that’s a big mistake,” Wen said.

Considering mental health concerns and educational outcomes, Wen said she thinks it’s best to have kids back to school — full time and in-person this fall.

But even mild cases of the COVID-19 can have long-term impacts for children, so safety precautions shouls be taken, she said.

Even vaccinated parents of unvaccinated children may want to wear masks indoors, said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.

Because vaccines are highly effective but not perfect, he said it’s possible adults could get breakthrough infections and pass them to their children.

“We haven’t formally proven yet how much diminution there is in the likelihood of transmitting it to someone else — including children — and that’s one of the reasons why you’ve got to be careful when you’re dealing with something like the Delta variant,” he said.

The best protection against variants, health experts say, is to get vaccinated as soon as possible.

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CBSDFW.com Staff