(CNN) — The first wave of coronavirus in the US isn’t over.

Nearly half of states are reporting a rise in new cases and some continue to break records in their daily reported cases. In the South, officials say more young people are testing positive. And across the US, experts continue to repeat warnings highlighting the need for social distancing and face covers.

And while some point to the rise in numbers as a result of more testing, health officials say more tests are only partly to blame.

“More testing does in fact turn out more cases. However … if widespread testing was the entire reason for the rise in cases, you’d expect to see the proportion of positive tests go down or at the very least remain steady. We’re not seeing that,” says Dr. Shoshana Ungerleider, a specialist in internal medicine at the California Pacific Medical Center.

“This has nothing to do with more testing and everything to do with behavior,” she said. “We need to talk to people about following the guidelines, wearing masks, avoiding crowds, staying home if possible and washing their hands.”

But parts of the country remain divided on wearing face masks in public, and more officials have had to consider making face covers in public a requirement.

As those discussions take place, the US Centers for Disease Control and Prevention says it will soon make an updated recommendation on the public health benefits on masks, a senior agency official told CNN.

The CDC has so far been conducting a scientific review on the topic, and a senior official with knowledge of the review says researchers are studying whether masks are not only “good for source control — and keeping you from giving it to others — but we’re also seeing if masks are going to protect you from getting (Covid-19) yourself.”

States with an increase in cases

The 23 states seeing a rise in new reported cases compared to the previous week, according to data from Johns Hopkins University, are: Arizona, California, Colorado, Delaware, Florida, Georgia, Hawaii, Idaho, Kansas, Kentucky, Michigan, Missouri, Montana, Nevada, Ohio, Oklahoma, South Carolina, Tennessee, Texas, Utah, Washington, West Virginia and Wyoming.

In California, the number of people hospitalized with coronavirus is the highest it’s been since the beginning of the pandemic. Across the state, 3,574 people were hospitalized Saturday. The state also reported the most new cases in a single day — 4,515 — since the pandemic’s start, according to data from the state’s health department.

California Gov. Gavin Newsom announced last week residents were required to wear a face covering in “high risk” settings, including indoor public space, public transportation or while seeking medical care.

In Texas, one of the first states to push forward with reopening, one mayor said he wished the state reopened more slowly while following coronavirus restrictions.

“When the governor started reopening, I wish he had done it a little slowly so we could have seen the numbers in each one of the phases before we moved on to the next phase,” Austin Mayor Steve Adler said Sunday night.

Texas Gov. Greg Abbott insists there’s no cause for concern and has rebuffed a request from several city mayors that would allow them to require masks in their cities.

“By making it so that cites couldn’t enforce masks, it sent the message to our community that maybe this thing was over,” Adler said.

States going steady

Meanwhile, ten states are trekking steady in new cases compared to last week: Arkansas, Indiana, Iowa, Minnesota, Nebraska, New Mexico, North Dakota, Oregon, Virginia and Wisconsin.

And 17 states are reporting a decline in new cases. They are Alabama, Alaska, Connecticut, Illinois, Louisiana, Maine, Maryland, Massachusetts, Mississippi, New Hampshire, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, South Dakota and Vermont.

In New York City, officials say they’re on track for the second phase of reopening which will begin Monday.

In a news release, the governor said the state continues to be “on the right path toward defeating the virus,” noting the state saw less than 1% positivity rate for the virus in the tests conducted Saturday.

Young groups testing positive for coronavirus

Across the South, some officials are raising alarm about an increased number of younger people testing positive for the virus.

In Mississippi, where one health officer called adherence to social distancing over the past weeks “overwhelmingly disappointing,” officials attributed clusters of new cases to fraternity rush parties.

In Texas, the governor said last week people under 30 made up a majority of new coronavirus cases in several counties. He said that increase in young infected people could be related to Memorial Day parties, visits to bars or other gatherings.

And in Florida, Gov. Ron DeSantis said Saturday cases are “shifting in a radical direction” toward populations in their 20s and 30s.

Those younger groups, he said, are mostly asymptomatic and don’t require clinical attention.

Experts have raised alarm about Florida’s climbing cases, saying the state could become the next US coronavirus epicenter. On Saturday, Florida reported 4,049 new cases — the most reported in a single day.

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