A late-summer uptick in COVID-19 infections, hospitalizations and deaths has some schools, hospitals and other businesses scrambling to keep illness from spreading.

The Centers for Disease Control and Prevention reported an 18.8% increase in hospitalizations due to COVID between Aug. 13 and Aug. 19, marking the sixth straight week of increased hospitalizations; and a 17.6% increase in COVID deaths from Aug. 20 to Aug. 26. Still, hospitalizations remain in the CDC’s “low” category in most places and aren’t as high as past years at this time.

Experts say currently circulating variants don’t necessarily cause more severe acute infection than previous variants, but there is still a risk of long-term effects from COVID. A new vaccine booster targeting the variants is expected to be available mid-September.

The increases in hospitalizations and deaths could be due to waning immunity among the general population from previous vaccines or infections and human behavior, such as schools starting and summer travel, Dr. S. Wesley Long, the medical director of diagnostic microbiology at Houston Methodist, told USA TODAY. Relaxed protective measures over the past year, including mask-wearing and testing, are also playing a part.

Here’s what to know about the current increase in cases: What do we know about current variants spreading?

We’re still seeing offshoots of the original omicron variant dominantly circulating, including XBB lineages and EG.5.

A new highly mutated variant that’s been discovered in several countries and a few states – BA.2.86 – was just discovered for the first time in Texas, Long said. But it’s difficult to say just how prevalent BA.2.86 may be, because surveillance methods used to identify which variants are circulating have ended in many places.

“There’s probably more out there than we realize,” he said.

It’s of interest to scientists because of how many mutations it has and how different it is from the dominantly circulating strains.

“The reason the BA.2.86 is concerning is because it’s sort of a mashup or remix of an earlier branch of omicron with a bunch of new spike mutations,” Long said. “(The mutations) may be essentially more likely to somewhat evade some immunity that we have to coronaviruses from infections and vaccines.” A spike in late-summer COVID-19 positive cases in the U.S. has some schools, hospitals, and businesses encouraging and at times requiring people to start masking up again.

What schools, hospitals are doing

School districts in Kansas and Texas cancelled in-person learning in a few places last week as attendance dropped drastically to prevent COVID and other illness from spreading further among staff and students.

Morris Brown College in Atlanta implemented a temporary mask requirement on campus because of COVID cases, WANF Atlanta News First reported.

Kaiser Permanente Northern California also reinstated a mask requirement for staff in its Santa Rosa facilities and encouraged visitors to wear masks as well, according to NBC Bay Area. Other hospitals in New York state have done the same. How common is long COVID?

It’s hard to know precisely how common it is for people to have ongoing, sometimes very severe, impacts from a previous COVID infection, according to Dr. Eric Topol, founder and executive vice president of Scripps Research, who has studied what is known as long COVID.

Topol told USA TODAY the number of people affected by long COVID could be more than 10 million people in the United States. The symptoms can range in severity, and can include constant fatigue, “brain fog,” cardiac issues neurologic symptoms and others, he said.

Dr. Tedros Adhanom Ghebreyesus, director-general of the World Health Organization, said earlier this year that about one in 10 infections could lead to conditions after a COVID infection, “suggesting that hundreds of millions of people will need longer-term care.”

While risk of a serious outcome from acute infection still remains higher for people with underlying conditions and the elderly, Topol said risk for long COVID is present for anyone regardless of their age or prior health status. The chances of long COVID are reduced when an infected person uses available treatments like Paxlovid and when they are up-to-date on vaccines and boosters, Topol said.

The only sure-fire way to prevent it, though, is to prevent COVID infection, experts say.

CDC Director Mandy Cohen said this week that there are up to 10,000 COVID hospitalizations per week, and the majority of those are among people over age 65.

The good news is, all the same protection measures that have existed since earlier in the pandemic will still work to avoid infection today, Long said. Those include:

Wearing a high-quality, well-fitting respirator
Avoiding crowds and people who are sick
Testing for COVID and staying home when positive or while sick
Staying up-to-date with booster doses, including the one that will be released this fall

Long said most people have resumed higher-risk behaviors, including going to work or school while having symptoms of illness, but it’s especially important to stay home now that cases are rising again due to lowered immunity.