Montana is a national hot spot for COVID infections, recording the highest percentage increase in new cases over the past seven days.

This article was published on Wednesday, September 22, 2021 in Kaiser Health News.

By Nick Ehli

BILLINGS, Mont. — Nurses fill the hospital room to turn a patient from his stomach to his back. The ventilator forcing air into him is most effective when he's on his stomach, so he is in that position most hours of the day, sedated and paralyzed by drugs.

Lying on his stomach all those hours has produced sores on his face, and one nurse dabs at the wounds. The dark lesions are insignificant given his current state, but she continues just the same, gently, soothingly, appearing to whisper to him as she works.

The man has been a patient at Billings Clinic for nearly a month, most of that time in the hospital's intensive care unit. He is among other patients, room after room of them, with the same grim tubes inserted down their throats. They have COVID-19 — the vast majority unvaccinated against the virus, the hospital says. Visitors generally aren't permitted in these rooms, but the man's mother comes most days to gaze through a glass window for the allowed 15 minutes.

This all happened Friday. He was dead, at age 24, by Sunday morning.

The hospital's morgue cart arrived at the ICU — as it frequently has these days — then the room was sterilized, another patient took the man's place, and the cycle began again. In the past week, 14 people have died of COVID here, the state's largest hospital.

"I do feel a little hopeless," said Christy Baxter, the hospital's director of critical care.

The situation has played out in hospitals around the nation since 2020. But now Montana is a national hot spot for COVID infections, recording the highest percentage increase in new cases over the past seven days. The state announced 1,209 new cases on Friday, and Yellowstone County, home to Billings Clinic, is seeing the worst of it. Last week, the county had 2,329 active cases, more than the next two counties combined.

What's different from the early scenes of the pandemic is the public's response. Not so long ago, the cheers of community support could be heard from the hospital parking lot. Now, tensions are so strained that Billings Clinic is printing signs for its hallways, asking that the staff members not be mistreated.

The ICU here has space for 28 patients but last Friday was operating at 160% capacity, Baxter said. To handle the overflow, nurses elsewhere provide care beyond their training as COVID patients fill other parts of the hospital. In the lobby of the emergency department, rooms roughly 6 feet by 6 feet have been fashioned with makeshift plastic walls. Ten members of the Montana Army National Guard arrived last week to help however they can. Hospital staffers volunteer to sit with dying patients. Beds line hallways.

"The problem is," said Brad Von Bergen, the hospital's ER manager, "we are running out of hallways."

The hospital announced it may soon implement "crisis standards of care," which basically means it will ration its equipment, staff and medicine, giving preference to those it can most likely save, regardless of vaccination status. It's an ugly system, abhorred by those who will wield it, with tiebreakers in place to decide who potentially lives and dies. Other hospitals in Montana have taken similar steps.

An overcrowded hospital also means that a person ― say, one injured in a car crash in rural eastern Montana and needing advanced hospitalization ― won't be able to get that care at Billings Clinic.

"We are at the point where we are not confident going forward that we can continue to meet all patients' needs," said Dr. Nathan Allen, the medical ethicist for Billings Clinic and its department chair for emergency medicine. "And that's heartbreaking."

"Nobody wants to be in a position where we may have to ration healthcare and potentially remove a ventilator from one patient who would likely die and give it to another," said Dr. Scott Ellner, the hospital's CEO. "Are we there? I would say we are very close."

To some extent, that rationing is already happening. A patient still hospitalized here with COVID might have benefited from a machine, known as an ECMO machine, needed to keep his heart and lungs functioning. Operating that machine, though, requires at least one nurse, 24 hours a day, usually for two to three weeks. Typically, it would be a last-ditch effort for the most critical of patients. Even with that care, the prognosis for the middle-aged man would be poor. Without it, Baxter said, he will assuredly die.

"The reality is I can't staff that," Baxter said. "Do you give that optimal care to one patient or do you give great care to five?"

Billings Clinic would hire more than 100 additional nurses if it could. The staffing shortage is not unique to this hospital; it's nationwide, meaning the needed help isn't arriving anytime soon. Baxter tells the story of a young nurse who quit, saying he had grown tired of lying to patients he knew would die.

"The patients look at you with that fear in their eyes and say, 'Am I going to make it?'" Baxter said. "You want to encourage them to not give up hope, but you also know the chances of survival are going to be slim."

Recently, a patient's dying wish was to have their preschool-age child come and sit with them, to see them one last time. That typically wouldn't be allowed, but an exception was made, with staffers at the hospital draping the child in oversized protective clothing, goggles and an N95 mask. Afterward, the nurse and doctor sobbed with the patient.

"The moral distress of working in healthcare is for many, many people extremely high right now," said Allen.

Intensifying that, he said, are patients or their loved ones mistreating doctors and nurses. Threats have on occasion required a police response. Screaming, profanity-laden insults are a daily occurrence. One patient threw his own feces at a doctor. Some, even in the face of an intubation tube, question the need to be vaccinated or the effectiveness of the medicine being prescribed.

Dr. Sara Nyquist, an emergency medicine physician, said she has been asked by a patient if she is a Republican or a Democrat.

"I said, 'I am your doctor,'" she recalled. "You do wonder how we got here."

Ellner, the clinic's CEO, said he doesn't understand what happened to civility. "There is a part of the society that wants to pretend that the COVID surge isn't really happening," he said. "But this is our reality every single day."

Jennifer Tafelmeyer, a nurse in the hospital's cardiovascular unit, said the best part of her job before the pandemic was helping patients improve, walking them down hallways, talking about diet and exercise, and eventually escorting them to the front door. That hasn't happened in a long time.

"We just don't get the wins," she said.

As she told the story, she stopped to wipe a tear. Moments before, she had learned that one of the patients on this floor was not expected to survive the night.

Allen predicted Billings Clinic hasn't yet seen the worst of the recent surge in infections.

"We are still seeing growing numbers in community cases," he said. "And we know hospitalizations lag behind new diagnoses. Unfortunately, it can absolutely get worse than where it is at."

In the meantime, he said, he expects the doctors and nurses here will rally as they have, taking comfort from words of thanks from many patients and gestures like a father bringing pizza to the emergency department as a show of appreciation for the care given his child.

"The most difficult things have been the big things," Allen said, "and the most inspiring things have been the little things."

Poor care coordination is one of the many shortcomings of Medi-Cal, which covers over a third of the state's population and nearly 40% of children under 18.

This article was published on Tuesday, September 21, 2021 in Kaiser Health News.

By Bernard J. Wolfson Photos by Heidi de Marco  

When Denise Williams' baby boy was 2 months old, she became alarmed by a rattling sound in his lungs and took him to the emergency room. While undergoing treatment, he spiraled into a disabling neurological disorder.

Now 2 years old, Markeano is attached to breathing and feeding tubes. He can't walk or move his arms.

"If I want him to sit up, I have to sit him up. If I want him to play with a car, I've got to put his hand on the car and move it back and forth," said Williams, 38, who lives with Markeano, her four other children and her husband, Marcus, in Adelanto, California, a small city in the High Desert region of San Bernardino County.

Markeano is enrolled in the Inland Empire Health Plan, a county-run managed-care insurer that provides coverage under Medi-Cal, California's version of the federal Medicaid program for people with low incomes or disabilities. He also receives care through California Children's Services, which covers kids with serious conditions.

But Williams still finds it difficult to get her son the specialized care he needs. What's worse, neither his insurers nor his doctors take responsibility for managing his care, she said. "No one coordinates the care except for me."

Poor care coordination is one of the many shortcomings of Medi-Cal, which covers over a third of the state's population and nearly 40% of children under 18. Advocates, patients and even the state auditor say Medi-Cal has failed to hold accountable the managed-care health plans that cover almost 12 million of its nearly 14 million enrollees.

To remedy these failings, the state has begun an ambitious contracting process that aims to commit the health plans to better service. The state's exact strategy is unclear. But it is expected to result in new rules for Medi-Cal managed care. The nine commercial insurers, including giants Health Net, Anthem Blue Cross, and Blue Shield of California, will have to bid for new contracts intended to set more rigorous care standards. While their members account for fewer than one-third of managed-care enrollees, the companies have made nearly $3 billion from Medi-Cal since 2014.

Non-commercial plans like the Inland Empire Health Plan, which are established by county authorities, won't have to submit bids, but they will be required to sign the new contracts.

"The state has had a lot of difficulty — because of skill and will — in managing and enforcing the terms of its existing contracts," said Alex Briscoe, head of the California Children's Trust and former director of Alameda County's Healthcare Services Agency. "This represents an opportunity not only to redesign the contracts but also to reimagine the state's role in enforcing them."

It's also an opportunity for the state to make a statement in selecting plans.

"Some are doing worse than others, and that should be taken into account in terms of decisions as the plans bid," said Edwin Park, a California-based research professor at the Georgetown University Center for Children and Families.

Jacey Cooper, California's Medicaid director, said the state's focus will be assuring that plans provide access to care and are committed to improving the outcomes of Medi-Cal beneficiaries.

The recontracting process is intertwined with an ambitious $6 billion experiment to move Medi-Cal beyond medicine into the realm of social services.

'Deficient Oversight'

Data shows that Medi-Cal plans are failing enrollees in many ways. Patients often have long waits or travel times for medical appointments, and get fragmented services and poor information about their care. Some communities of color, as well as rural residents, receive lower-quality service than others.

Faulty treatment hits the 4.6 million kids in managed-care Medi-Cal particularly hard because children need a lot of routine care, and many are not getting it. In July, close to 500 advocacy and provider groups sent a letter to the Department of Healthcare Services, which runs Medi-Cal, urging it to make the managed-care plans improve pediatric care. "The deficiencies in the Medi-Cal managed care program contribute to health disparities for children across the state that can last a lifetime," they wrote. The new contracts, the letter said, should require health plans to fix the problem.

Federal law provides significant protection for all children in Medi-Cal and other state Medicaid programs. It requires coverage for regular checkups, immunizations, and other preventive and diagnostic care.

But state data shows that Medi-Cal managed-care plans often fail to meet these requirements. Only about one-quarter of infants and toddlers in Medi-Cal get the recommended number of well-child visits and screenings for developmental delays. The plans fall short on immunizations as well.

A 2019 report by the California State Auditor ranked California 40th among state Medicaid programs in use of preventive services by children.

The report blamed the state's poor performance on "deficient oversight of the managed care plans" and an insufficient number of healthcare providers willing to accept Medi-Cal's low payment rates.

"I don't see how we can have a high-performing Medi-Cal system that doesn't do well on those basic services for kids," said Mike Odeh, health policy director at Children Now, an Oakland-based advocacy group.

To be fair, Medi-Cal has had its share of successes, too, including early and robust expansion of enrollment under the Affordable Care Act, extension of coverage to large numbers of immigrants without legal documents, and pioneering programs that address not only medical and mental health but also the social and environmental circumstances of enrollees.

Nonetheless, Medi-Cal managed-care plans often earn poor to mediocre marks for the quality of their care. Meanwhile, the largest commercial plans have profited handsomely from the program, especially since the expansion of Medicaid in 2014. That helps explain why the rebidding process is such a sensitive matter for them. Health Net, Anthem Blue Cross, Molina Healthcare and Blue Shield of California all declined to discuss their bidding strategies with KHN.

Collectively, the commercial plans have generated $2.9 billion in net profits from Medi-Cal since fiscal year 2014, according to data provided by the state. Health Net, the state's largest commercial Medi-Cal insurer, with around 2 million enrollees, accounted for $2.1 billion of that amount. Anthem Blue Cross, the second-largest commercial Medi-Cal plan, with 1.3 million enrollees, accounted for $873 million.

An Anthem Blue Cross spokesperson noted that Medi-Cal managed-care plans are required by law to spend at least 85 cents of every dollar on medical care or efforts to improve care. That, along with other factors, limits the health plans' profits, he said.

Kaiser Permanente, which is at or near the top of Medi-Cal quality scores, has lost money in the program every year since 2014 — and before that, too.

Health Net and Anthem Blue Cross get poor to mediocre marks on key pediatric services in many counties, according to state data. Health Net Medi-Cal plans in Sacramento, Kern, Stanislaus and San Diego counties, for example, were at or near the bottom of the pack in timeliness of pediatric appointments.

A Health Net spokesperson said the company has improved over the past two years and now outperforms its competitors on state quality indicators in nine of the 13 counties where it operates.

The 2019 state audit, citing earlier concerns about incomplete and inaccurate reporting, noted that the integrity of the state's quality data can be hard to assess.

And non-commercial plans often have low scores, too. "Quality is stubbornly low across all plans in Medi-Cal. Nobody gets a pass here," said Cary Sanders, senior policy director at the California Pan-Ethnic Health Network.

The state rarely holds any of the plans fully to account, advocates and Medi-Cal experts say. The Department of Healthcare Services started imposing financial penalties for poor quality only in 2017, and since then it has levied only two such fines: one against Health Net for $335,000 and one against the publicly run Health Plan of San Joaquin for $135,000.

The department does require subpar performers to devise so-called corrective action plans, but critics say they rarely produce significant improvement.

Even if enforcement were effective, the standards for Medi-Cal plans are too low, advocates say. Until 2019, insurers needed to be only in the 25th percentile of Medicaid plans nationally to avoid corrective action. The department raised the bar to the 50th percentile in 2019 but has not enforced it so far because of the COVID-19 pandemic.

The department next year will begin penalizing any health plan that "fails to exceed, rather than just meet" the minimum performance level on any measure, said Cooper, the state's Medicaid chief. It will do so every year, rather than target only persistently poor performers, she said.

Pay for Performance

In June, the Department of Healthcare Services released preliminary details on the bidding process, outlining some of the new requirements. It expects to issue more details by year's end but won't announce plan selections until the end of 2022. The new contracts are slated to take effect Jan. 1, 2024.

But will the state lean hard enough on the plans? Based on the documents released so far, this could be a "potential missed opportunity," said Sanders. "There aren't enough teeth here to improve health plan accountability."

Other advocates cite what they say has been a cozy relationship between health plans and the state. "I just think the whole delivery system has historically been filled with a lot of politics, favoritism, good old boys," said Isabel Becerra, CEO of the Coalition of Orange County Community Health Centers, whose members provide Medi-Cal services in the county.

Some advocates and analysts say the best way for the state to hold the managed-care plans' feet to the fire is to tie the fixed monthly rates it pays them to their performance on a number of measures, including preventive services and health equity.

"If you want to change how they work, you have to change the incentives that drive them," said Briscoe, of the California Children's Trust.

Medicaid chief Cooper said her staff is working to link payment to quality and health equity.

Some advocates say the state should withhold payments from poorly performing plans. The plans, however, would prefer being rewarded for exceeding expectations to being dinged for failing to meet them.

A Communication Breakdown

The rebidding process is expected to reduce the number of insurance companies participating in Medi-Cal — and some experts say that's a good thing.

"The idea of competition is you're supposed to be competing on the basis of quality, but if there are too many choices beneficiaries aren't able to discern the differences," said Georgetown University's Park.

In some regions, the Medi-Cal health plans that contract directly with the state outsource care and administrative tasks to other plans or physician groups. L.A. Care, for example, farms out enrollees to subcontractors such as Kaiser Permanente, Anthem Blue Cross and Blue Shield of California. The Department of Healthcare Services says that in evaluating the bids it will look favorably on health plans that commit to keeping closer tabs on their subcontractors.

The state reports quality scores only for plans with which it contracts directly, and their data can be skewed by wide variation in the performance of the subcontractors.

Moreover, the divided responsibility between health plans and their subcontractors can confuse beneficiaries.

"The subcontractor says, 'No, call the plan' — and the plan says, 'Call the subcontractor,' and there's really no accountability," said Abigail Coursolle, a senior attorney at the National Health Law Program in Los Angeles.

Denise Williams faces a similar problem. She said the Inland Empire Health Plan does not communicate effectively — or at all — with California Children's Services or Markeano's doctors. As a result, she is saddled with hours of legwork to find care for her son, whether speech, swallowing and cognitive therapy or extra oxygen tanks to make sure he doesn't run out during long car trips to see his doctors.

"They tell me, 'Your pediatrician or neurologist should be doing this.' Then when I talk to the pediatrician and the neurologist, they say, 'Talk to your insurance,'" Williams said. "So it's like, 'I already talked to you guys. Can't you guys talk to each other — or can we get on a three-way? Because this is draining. I've got a kid that I need to take care of.'"

Inland Empire Health acknowledged the gaps in coordination among managed-care plans, California Children's Services and providers, saying it was "eager to embrace the care coordination improvements" that the state says it will require. The new contracts also will require plans to address some of the nonmedical problems that can compromise health, such as inadequate housing, unclean air and water, and food insecurity.

In addition to being predominantly poor, over two-thirds of Medi-Cal enrollees are from non-white communities that have historically been socially and economically marginalized — which is why the state says it will put a high priority on reducing healthcare inequities.

Denise Williams, who is Black, wonders if her travails are related to long-standing inequities.

"Sometimes I don't know if it's because of my color or what," she said. "I try to remain calm at all times, so that way it's not a stereotype of an angry Black lady or whatever. But at the same time, I'm my kid's only advocate, so if I never say nothing, my kid would just be lying in the bed all day."

California Healthline correspondent Angela Hart contributed to this report.

This story was produced by KHN, which publishes California Healthline, an editorially independent service of the California Healthcare Foundation.

Bernard J. Wolfson: bwolfson@kff.org, @bjwolfson

Delta, currently the primary variant in the United States, is far more contagious than the original coronavirus, so the density of virus in the air is greater.

This article was published on Monday, September 20, 2021 in Kaiser Health News.

By Amanda Michelle Gomez

In recent months, some European airlines have banned the use of cloth face coverings to control the spread of the coronavirus during air travel, instead favoring surgical masks — sometimes referred to as medical or disposable — and N95 respirators.

It's another salvo in the debate over the effectiveness of the ubiquitous cloth mask, which sprang into fashion when surgical masks and N95s were harder to find in the pandemic's early days. The Centers for Disease Control and Prevention still promotes cloth face coverings in its guidance about masks.

And masks remain a critical mitigation tool because people primarily become infected with SARS-CoV-2, the virus that causes COVID-19, by inhaling small aerosol particles that linger in the air or large respiratory droplets produced in coughs and sneezes.

But the science is changing. Delta, currently the primary variant in the United States, is far more contagious than the original coronavirus, so the density of virus in the air is greater.

Some experts have adjusted their advice proportionally. "Given the delta variant that's out there, you probably need to upgrade your mask," Dr. Ashish Jha, a leading COVID expert and dean of the Brown University School of Public Health, said on "Fox News Sunday" earlier this month.

What Type of Mask Should You Wear?

Don't worry if you are confused. Mask guidance has been mixed since the dawn of the pandemic, and new research has altered conventional thinking. We decided to dig in and sort out the latest developments.

First, people were told masking wasn't necessary. Soon after, this recommendation changed, but the public was advised against purchasing surgical-style masks used by health professionals because of dire shortages of such protective gear. Americans instead were told to spring for cloth masks or make do-it-yourself versions. Shortages do not appear to be as big a problem now, though the CDC still advises against choosing N95 respirators.

As recently as late August, the nation's top infectious-disease doctor, Dr. Anthony Fauci, declined to recommend higher-quality masks. "Instead of worrying about what kind of mask, just wear a mask," he told "The Mehdi Hasan Show" on MSNBC.

So, what gives? Dr. Peter Chin-Hong, an expert on infectious diseases at the University of California-San Francisco, said Fauci was taking a harm-reduction approach. "It probably is more important to wear something that you feel comfortable with, and you can wear for long periods of time if you're going into a particular environment … rather than saying you need to wear the gold standard thing at all times," he said.

"A baseline should be a surgical mask," added Chin-Hong. "It's easier to implement. It's cheap, albeit not always environmentally friendly." Personally, he wears only N95s when wildfires are blazing. "Even in the hospital, I'm mainly wearing a surgical mask," he said.

While he thinks government and public health officials should emphasize wearing surgical masks, Chin-Hong said cloth masks can offer enough protection in certain circumstances. For example, a fully vaccinated person, he said, would likely get adequate protection by wearing a cloth face covering for brief periods indoors when the venue is not at capacity. A lot depends on the context, so he provided these questions to help the decision-making process: If you are going indoors, will the building be especially crowded? How long will you be inside? Will everyone most likely be masked? Are you and others around you fully vaccinated? Are you immunocompromised?

The riskier the situation, the more likely the higher-quality mask is the best option. "Nothing is zero risk, so it's just a matter of risk reduction," Chin-Hong said.

"So definitely, masks need to be stepped up to fight delta, but it does not mean those who cannot afford N95s have no options," said Raina MacIntyre, head of the biosecurity research program at the University of New South Wales in Sydney, Australia, who has conducted many studies on masks.

MacIntyre said it is "possible to design a high-performing cloth mask." An experimental lab study she co-authored found a layered cloth mask can effectively block droplets. The study, published in May in the journal ACS Biomaterials Science & Engineering, recommends using a minimum of three layers — a combination of cotton/linen and polyester/nylon — to resemble the droplet-blocking performance of surgical masks.

Not only is layering important to improve filtration but so is fit. A CDC-recommended technique for improving the fit of either a cloth or surgical mask is knotting the straps and tucking the sides. A mask is generally a good fit if you feel warm air coming through the front of the mask as you inhale and exhale.

What Does the Research Say?

A large-scale, real-world study published this month found surgical masks especially effective at reducing symptomatic infections. These types of masks prevented 1 in 3 infections among people 60 and older.

Researchers from Yale, Stanford and the nonprofit GreenVoice monitored more than 340,000 adults in rural Bangladesh for at least eight weeks. Roughly half the Bangladeshis received interventions like free mask distribution and promotion. Villages that received interventions saw mask use jump from 13% to 42%. The same villages reported fewer confirmed COVID infections and a lower incidence of related symptoms.

Villages where cloth masks were given out reported an 8.5% reduction in symptoms, while villages that received surgical masks reported a 13.6% reduction. When a third of adults with symptoms commonly associated with COVID agreed to get their blood tested for the virus, researchers discovered an 11% reduction among those who wore surgical masks. Researchers observed a 5% reduction in infections among those who wore cloth masks. This study was conducted before the delta variant was circulating widely in the country. The study has not yet undergone peer review, but some experts have already heralded its methodology and results.

"When I saw those results, I threw away my cloth mask," said Stephen Luby, a co-author of the study and professor of infectious disease at Stanford University. "If delta is circulating and if you're going to wear a mask, why don't you wear one that the data tell you is good?"

"We find very strong evidence that surgical masks are effective," added Jason Abaluck, an economist at Yale who helped lead the study. "My read of that is that cloth masks are probably somewhat effective. They are probably better than nothing."

Abaluck suspects his study offers mixed evidence for cloth masks because only about a third of those who reported symptoms consented to blood testing for COVID. In other words, the sample size was too small to observe anything significant. "The most likely interpretation of this whole constellation of results is that [cloth masks] actually do help. They actually do make you less likely to get COVID. That's why we saw fewer symptoms," he said. A second possibility is that cloth masks prevent other respiratory diseases that have similar symptoms, he said.

Multiple observational studies and trend analyses found community masking, which includes the use of cloth masks, reduces the spread of COVID. The researchers of the Bangladesh study said those studies had drawbacks, which is why they conducted a randomized clinical trial. For example, some of those studies could not observe the independent effect of masks in real-world settings because they looked at the aftermath of mask mandates, which were often coupled with other COVID mitigation steps such as physical distancing. However, they agreed with those studies' overall assessment: People who wear masks are less likely to get infected than people who don't.

"This is the nature of science. Science evolves," Luby said. "We had evidence that we get some protection from cloth masks, and we now have newer evidence that we get better protection from surgical masks."

Amanda Michelle Gomez: amandag@kff.org, @amanduhgomez

Until the delta variant laid siege this summer, nearly all children seemed to be spared from the worst ravages of COVID, for reasons scientists didn't totally understand.

This article was published on Friday, September 17, 2021 in Kaiser Health News.

By Liz Szabo

Eighteen months into the COVID-19 pandemic, with the delta variant fueling a massive resurgence of disease, many hospitals are hitting a heartbreaking new low. They're now losing babies to the coronavirus.  

The first reported COVID-related death of a newborn occurred in Orange County, Florida, and an infant has died in Mississippi. Merced County in California lost a child under a year old in late August.

"It's so hard to see kids suffer," said Dr. Paul Offit, an expert on infectious diseases at Children's Hospital of Philadelphia, which — like other pediatric hospitals around the country — has been inundated with COVID patients.

Until the delta variant laid siege this summer, nearly all children seemed to be spared from the worst ravages of COVID, for reasons scientists didn't totally understand.

Although there's no evidence the delta variant causes more severe disease, the virus is so infectious that children are being hospitalized in large numbers — mostly in states with low vaccination rates. Nearly 30% of COVID infections reported for the week that ended Sept. 9 were in children, according to the American Academy of Pediatrics.

Doctors diagnosed more than 243,000 cases in children in the same week, bringing the total number of COVID infections in kids under 18 since the onset of the pandemic to 5.3 million, with at least 534 deaths.

Experts say it's a question of basic math. "If 10 times as many kids are infected with delta than previous variants, then, of course, we're going to see 10 times as many kids hospitalized," said Dr. Dimitri Christakis, director of the Center for Child Health, Behavior and Development at the Seattle Children's Research Institute.

But the latest surge gives new urgency to a question that has mystified scientists throughout the pandemic: What protects most children from becoming seriously ill? And why does that protection sometimes fail?

"This is an urgent and complex question," said Dr. Bill Kapogiannis, senior medical officer and infectious-disease expert at the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

"We are doing everything we can to address it, using all the tools we have available," Kapogiannis said. "Answers can't come soon enough."

Investigating Immune Systems

For much of the pandemic, doctors could only guess why children's immune systems were so much more successful at rebuffing the coronavirus.

Despite the alarming number of hospitalized children in the recent surge, young people are much less likely to become critically ill. Fewer than 1% of children diagnosed with COVID are hospitalized and about 0.01% die — rates that haven't changed in recent months, according to the American Academy of Pediatrics. Most children shrug off the virus with little more than a sniffle.

A growing body of evidence suggests that kids' innate immune systems usually nip the infection early on, preventing the virus from gaining a foothold and multiplying unchecked, said Dr. Lael Yonker, an assistant professor of pediatrics at Massachusetts General Hospital.

In a series of studies published in the past year, the husband-and-wife team of Drs. Betsy and Kevan Herold found that children have particularly strong mucosal immunity, so called because the key players in this system are not in the blood but in the mucous membranes that line the nose, throat and other parts of the body that frequently encounter germs.

These membranes act like the layered stone walls that protected medieval cities from invaders. They're made of epithelial cells — these also line many internal organs — which sit side by side with key soldiers in the immune system called dendritic cells and macrophages, said Betsy Herold, chief of the division of pediatric infectious diseases at the Albert Einstein College of Medicine.

Significantly, these cells are covered in proteins — called pattern recognition receptors — that act like sentries, continuously scanning the landscape for anything unusual. When the sentries notice something foreign — like a new virus — they alert cells to begin releasing proteins called interferons, which help coordinate the body's immune response.

In an August study in Nature Biotechnology, Roland Eils and his colleagues at Germany's Berlin Institute of Health found that kids' upper airways are "pre-activated" to fight the novel coronavirus. Their airways are teaming with these sentries, including ones that excel at recognizing the coronavirus.

That allows kids to immediately activate their innate immune system, releasing interferons that help shut down the virus before it can establish a foothold, Eils said.

In comparison, adults have far fewer sentinels on the lookout and take about two days to respond to the virus, Eils said. By that time, the virus may have multiplied exponentially, and the battle becomes much more difficult.

When innate immunity fails to control a virus, the body can fall back on the adaptive immune system, a second line of defense that adapts to each unique threat. The adaptive system creates antibodies, for example, tailored to each virus or bacterium the body encounters.

While antibodies are some of the easiest pieces of the immune response to measure, and therefore often cited as proxies for protection, kids don't seem to need as many to fight COVID, Betsy Herold said. In fact, the Herolds' research shows that children with COVID have fewer neutralizing antibodies than adults. (Both kids and adults usually make enough antibodies to thwart future coronavirus infections after natural infection or vaccination.)

While the adaptive immune system can be effective, it can sometimes cause more harm than good.

Like soldiers who kill their comrades with friendly fire, a hyperactive immune system can cause collateral damage, triggering an inflammatory cascade that tramples not just viruses, but also healthy cells throughout the body.

In some COVID patients, uncontrolled inflammation can lead to life-threatening blood clots and acute respiratory distress syndrome, which occurs when fluid builds up in the air sacs of the lung and makes it difficult to breathe, Betsy Herold said. Both are common causes of death in adult COVID patients.

Because kids typically clear the coronavirus so quickly, they usually avoid this sort of dangerous inflammation, she said.

Research shows that healthy children have large supplies of a type of peacekeeper cell, called innate lymphoid cells, that help calm an overactive immune system and repair damage to the lungs, said Dr. Jeremy Luban, a professor at the University of Massachusetts Medical School.

Kids are born with lots of these cells, but their numbers decline with age. And both children and adults who are sick with COVID tend to have fewer of these repair cells, Luban said.

Men also have fewer repair cells than women, which could help explain why males have a higher risk of dying from COVID than females.

Both children and adults can develop "long COVID," the lingering health issues experienced by about 10% of younger adults and up to 22% of those 70 and older. Studies suggest that 4% to 11% of kids have persistent symptoms.

Unanswered Questions

Scientists have fewer clues about what goes wrong in certain children with COVID, said Kevan Herold, who teaches immunobiology at the Yale School of Medicine.

Research suggests that children have more robust innate immune systems than adults because they have experienced so many recent respiratory infections, within their first few years, which may prime their immune systems for subsequent attacks.

But not all children shrug off COVID so easily, Eils said. Newborns haven't been alive long enough to prime their immune systems for battle. Even toddlers may fail to mount a strong response, he said.

At Children's Hospital New Orleans, half of COVID patients are under 4, said Dr. Mark Kline, a specialist in infectious diseases and physician-in-chief.

"We've had babies as young as 7 weeks, 9 weeks old in the ICU on ventilators," Kline said. "We had a 3-month-old who required ECMO," or extracorporeal membrane oxygenation, in which the patient is connected to a machine similar to the heart-lung bypass machine used in open-heart surgery.

Even previously healthy children sometimes die from respiratory infections, from COVID to influenza or respiratory syncytial virus.

But studies have found that 30% to 70% of children hospitalized with COVID had underlying conditions that increase their risk, such as Down syndrome, obesity, lung disease, diabetes or immune deficiencies. Premature babies are also at higher risk, as are children who've undergone cancer treatment.

One thing hospitalized kids have in common is that almost none are vaccinated, said Dr. Mary Taylor, chair of pediatrics at the University of Mississippi Medical Center.

"There's really no way to know which child with COVID will get a cold and be just fine and which child will be critically ill," Taylor said. "It's just a very helpless sensation for families to feel like there is nothing they can do for their child."

Although scientists have identified genetic mutations associated with severe COVID, these variants are extremely rare.

Scientists have had more success illuminating why certain adults succumb to COVID.

Some cases of severe COVID in adults, for example, have been tied to misguided antibodies that target interferons, rather than the coronavirus. An August study in ScienceImmunology reported that such "autoantibodies" contribute to 20% of COVID deaths.

Autoantibodies are very rare in children and young adults, however, and unlikely to explain why some youngsters succumb to the disease, said study co-author Dr. Isabelle Meyts, a pediatric immunologist at the Catholic University of Leuven in Belgium.

Although hospitalizations are declining nationwide, some of the most serious consequences of infection are only now emerging.

Two months into the delta surge, hospitals throughout the South are seeing a second wave of children with a rare but life-threatening condition called multisystem inflammatory syndrome, or MIS-C.

Unlike kids who develop COVID pneumonia — the major cause of hospitalizations among children — those with MIS-C typically have mild or asymptomatic infections but become very ill about a month later, developing symptoms such as nausea, vomiting, a rash, fever and diarrhea. Some develop blood clots and dangerously low blood pressure. More than 4,661 children have been diagnosed with MIS-C and 41 have died, according to the Centers for Disease Control and Prevention.

Although scientists still don't know the exact cause of MIS-C, research by Yonker of Massachusetts General and others suggests that viral particles may leak from the gut into the bloodstream, causing a system reaction throughout the body.

It's too soon to tell whether children who survive MIS-C will suffer lasting health problems, said Dr. Leigh Howard, a specialist in pediatric infectious diseases at Vanderbilt University Medical Center.

Although an August study in The Lancet shows that delta doubles the risk of hospitalization in adults, scientists don't know whether that's true for kids, said Dr. Anthony Fauci, the country's top infectious-disease official.

"We certainly don't know at this point whether children have more severe disease, but we're keeping our eye on it," he said.

To protect children, Fauci urged parents to vaccinate themselves and children age 12 and up. As for children too young for COVID shots, "the best way to keep them safe is to surround them by people who are vaccinated."

Liz Szabo: lszabo@kff.org, @LizSzabo