Another US Covid-19 surge may look different, experts say, particularly for younger people. Here’s how

Experts say Covid-19 vaccinations in the United States are going extremely well – but more people need to be protected and the country may be at the start of another surge.

Over the weekend, the number of vaccinations reported in a single day by the US Centers for Disease Control and Prevention (CDC) went up more than 4 million for the first time.

The country is averaging more than 3 million doses daily, according to CDC data.

But only about 18.8% of Americans are fully vaccinated, CDC data shows, and Covid-19 cases in the country have recently seen concerning increases.

“I do think we still have a few more rough weeks ahead,” Dr. Celine Gounder, an infectious diseases specialist and epidemiologist, told CNN on Sunday. “What we know from the past year of the pandemic is that we tend to trend about three to four weeks behind Europe in terms of our pandemic patterns.”

SAN ANTONIO, TX - MARCH 29: A nurse fills up a syringe with the Moderna Covid-19 vaccine at a vaccination site at a senior center on March 29, 2021 in San Antonio, Texas. Texas has opened up all vaccination eligibility to all adults starting today. Texas has had a slower roll out than some states and with the increase in eligibility leaders are hoping more and more citizens get vaccinated. (Photo by Sergio Flores/Getty Images)

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The highly contagious B.1.1.7 variant has fueled an alarming rise in Covid-19 cases and hospitalizations in parts of Europe. And experts worry the US could be next if Americans don’t double down on safety measures until more people are vaccinated.

What’s worse, experts say, is that the variant is changing the pandemic’s playbook and could spell trouble for younger groups that haven’t yet been vaccinated.

“We have to think about the B.1.1.7 variant as almost a brand-new virus,” said Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine. “It’s acting differently from anything we’ve seen before, in terms of transmissibility, in terms of affecting young people, so we have to take this very seriously.”

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CDC updates its guidance on cleaning surfaces in home

The CDC has updated its guidance for cleaning and disinfecting surfaces to prevent the spread of the coronavirus, Director Dr. Rochelle Walensky said Monday at the White House COVID-19 Response Team briefing.

The science has shown that people can get infected via contaminated surfaces, but the risk is low, Walensky said. Regular cleaning of homes and other places with soap or detergent works. Disinfection is often not necessary.

“Disinfection is only recommended in indoor settings, schools and homes where there has been a suspected or confirmed case of Covid-19, within the last 24 hours,” Walensky said.

In most cases, fogging, fumigation and electrostatic spraying is not recommended as a primary method of disinfection, and actually carries several safety risks.

Surface transmission can also be reduced by wearing masks correctly and proper handwashing, she said.

Variants causing cases to rise

Covid-19 cases have increased for a fourth straight week, Walensky said.

“We know that these increases are due, in part, to more highly transmissible variants, which we are very closely monitoring,” Walensky said.

She also said that a number of the clusters identified among young people are connected to participation in youth sports and extracurricular activities. The CDC guidelines suggest those activities should be limited.

“I understand that people are tired and that they are ready for this pandemic to be over, as am I,” Walensky said. “Please, continue to hang in there, and to continue to do things that we know prevent the spread of the virus.”

The difference between previous surges and another possible surge is “the people most affected now are the younger individuals,” emergency physician Dr. Leana Wen told CNN on Sunday.

Registered nurse Erica Fairfield, right, works at the Hackley Community Care COVID-19 curbside testing site at 2700 Baker Street in Muskegon Heights, Mich., Friday, Nov. 13, 2020. (Cory Morse/The Grand Rapids Press via AP)

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Older populations have been prioritized nationwide for Covid-19 vaccinations while only recently have states detailed plans to open eligibility to all people who vaccines have been authorized for in the US.

New Jersey and Maryland on Monday announced new starting dates for when people 16 and older will be eligible to be vaccinated.

About 55% of Americans 65 and older have been fully vaccinated, according to the CDC, while more than 75% of that same age group have gotten at least one Covid-19 vaccine dose.

But while that age group is relatively well protected, Wen said, younger groups are still vulnerable as the B.1.1.7 variant circulates. The variant is more contagious and research suggests it may also be more deadly

“We’re seeing in places like Michigan that the people who are now getting hospitalized by large numbers are people in their 30s and 40s,” Wen said. “And now we’re even seeing children getting infected in larger numbers, too.”

It’s not just Michigan.

“What we’re seeing is pockets of infection around the country, particularly in younger people who haven’t been vaccinated, and also in school-aged children,” former Food and Drug Administration commissioner Dr. Scott Gottlieb told CBS’s “Face the Nation” on Sunday.

“If you look what’s happening in Michigan, in Minnesota, in Massachusetts, for example, you’re seeing outbreaks in schools and infections in social cohorts that haven’t been exposed to the virus before.”

“The infection is changing its contours in terms of who’s being stricken by it right now,” he added.

In Florida’s Orange County, officials reported late last month a rise in Covid-19 cases in the 18-25 age group.

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And a third of all of the county’s Covid-19 hospitalizations were people younger than 45, according to Dr. Raul Pino, director of the Florida Department of Health in Orange County.

The American Academy of Pediatrics said Monday there were at least 63,862 new child Covid-19 cases identified through testing last week. After slight increases in cases over the past two weeks, the number of new child Covid-19 cases were similar to the previous week.

Children made up between 6% and 18.8% of those who were tested for Covid-19, and 5.2% to 31.9% of children tested were positive for the coronavirus, depending on the state.

The definition of a child cases varies by state, the group said.

A lifeguard calls to swimmers in Miami Beach, Florida, on March 27.

Spring break travel soars

The Transportation Security Administration says it screened 1.54 million people at airports across the country Sunday, just shy of a pandemic record set Friday when 1.58 million people were screened. More than 6 million people have been screened since Thursday.

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Sunday’s screening rate is more than 10 times greater than the bottomed-out figures of a year ago, but still well below 2019 levels. TSA figures have been higher than 1.5 million for three of the past seven days and higher than one million for 25 days in a row.

Friday, the CDC said those who are fully vaccinated can travel at low risk to themselves, but said non-essential travel should still be avoided.

Delta Air Lines said it had to fill some middle seats on weekend flights to keep up with demand, even though its cap on seating capacity does not end until May 1.

‘Pretty good’ vs. ‘super-duper’ vaccination protection

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The decision on whether to delay second doses of Covid-19 vaccines in order to administer first doses to many people as possible may depend on available supply, Dr. Kent Sepkowitz, an infectious disease specialist at Memorial Sloan Kettering, told CNN on Monday.

“If the stockpile is running low, then yeah, I think we ought to optimize ‘pretty good’ vaccination for more people than ‘super-duper’ protection for fewer,” Sepkowitz said.

“If, however, the vaccine stockpile isn’t so sparse,” he added, “then I think we plow ahead with what we’re doing” – which means sticking with a two-dose regimen for the Pfizer/BioNTech and Moderna vaccines.

Dr. Anthony Fauci said earlier at a White House briefing that delaying second doses could put people in a “tenuous zone,” especially with variants circulating.

CNN’s Virginia Langmaid, Jen Christensen, Pete Muntean, Naomi Thomas, Ganesh Setty, Anna Sturla, Ralph Ellis and Heather Law contributed to this report.