By Deidre McPhillips, CNN
Updated: Fri, 14 Jan 2022 23:00:23 GMT
New research suggests that children under 5 who are infected with the Omicron variant of the coronavirus have "significantly less severe outcomes" than those who catch the Delta variant. The preprint study adds to a growing set of evidence, with the researchers calling Omicron "inherently milder" than Delta among children under 5.
But Covid-19 case rates and hospitalizations among children have reached record highs in recent weeks. With case rates as high as they are, even small risks of severe outcomes can lead to large numbers of children in the hospital, experts say.
"When you have such huge numbers of infected individuals, even a low likelihood of a severe event -- which is generally the case in children; they generally tolerate the virus much better than adults do -- it stands to reason that you're going to see more kids with rare and potentially serious consequences of the infection," said Dr. Richard Malley, an infectious disease specialist at Boston Children's Hospital.
"In many ways, both statements could be true. Omicron could be milder in kids than previous variants, but we could still be seeing significantly more cases of severe Covid, even with a milder virus."
For the new study, researchers analyzed electronic health records for about 80,000 children under the age of 5 who were infected with Covid-19 for the first time in the United States. This age group is not yet eligible to be vaccinated, and the researchers note that low rates of prior Covid-19 infection also limit their pre-existing immunity.
The study found about 70% reduction in hospitalizations, ICU admissions and mechanical ventilation among children infected with Omicron compared with those infected with Delta. They also found a 29% reduction in visits to the emergency room. Data on deaths was not included, as there were so few reported.
Overall, about 1% of children infected with Omicron were hospitalized, compared with about 3% of children with Delta, according to the study.
"Despite this encouraging result, further studies are needed to monitor the longer-term acute consequences from Omicron infection, the propensity for development of 'long COVID,' the rapidity of spread, potential for mutation, and how prior infections alter clinical responses," the researchers wrote.
In the last week of December, there were about 10 Covid-19 hospitalizations for every 100,000 children under the age of 5, higher than at any other point during the pandemic, according to data from the US Centers for Disease Control and Prevention. And although the results are promising at a broad population level, the experience for those families with children who do end up in the hospital is no less severe.
"Imagine you're the parent. Imagine you're the child. I mean, these things are extraordinarily stressful," Malley said. "The child who gets admitted does not know that their hospitalization is going to be short or less severe. The parent doesn't know that, either."
And in addition to not being eligible for vaccination, children face a few additional unique risk factors that could drive up transmission -- and the potential chances for a severe outcome.
"I don't think the virus is really acting differently in kids than it is in adults. But I think kids are different than adults," said Dr. Karen Ravin, chief of infectious diseases at Nemours Children's Hospital in Delaware.
"Kids are kids, and so they are more likely to get really close to people when they talk to them. When they play, they kind of put their heads together. They tend to touch everything and get close to everybody, so I think for any kind of respiratory virus, that clearly puts them a little bit more at risk than adults who are maybe more apt to keep our distance."
And with schools and preschools now back in session, this transmission is more likely, which could be why children started to account for a larger share of cases and hospitalizations during the Delta surge than earlier waves, too.
"It's a different playing field," Ravin said.
In addition to Covid-19 patients, hospitals are now caring for more children for whom care had been postponed or otherwise avoided.
"Early on in the pandemic, the hospital was pretty empty. There weren't a lot of traumas, other acute injuries or medical concerns. Unfortunately, with the pandemic -- and this is true for both pediatric patients and adults -- a lot of people kind of deferred or waited to get medical care for different concerns because of fear of the pandemic," Ravin said.
"Now, we're seeing the after-effects, where we have a lot of patients admitted right now for a lot of other acute medical concerns and a lot of kids admitted with Covid on top of that. So there are just a lot of patients in the hospital."
All things considered, experts say, parents should not make changes to the prevention measures they've been taking.
"There are things parents can do that they couldn't do a year ago. One of them is to make sure that everybody in the entourage of a child who's eligible for vaccination or for boosting get that vaccination or boosting," Malley said.
"Also, maintain the same sort of preference for outdoor activities over indoor activities, and be careful that masks be worn whenever they're indoors. Those things, I think, need to be re-emphasized."
The new study has not been peer-reviewed or published in a professional journal. It included about 7,000 children infected during a time when the Omicron variant was predominant and about 63,000 children infected when Delta was predominant. Virus samples were not sequenced for each individual child but were instead assumed based on broader sequencing data from the time. Omicron accounted for about 92% of samples during the two weeks ending January 6, while Delta accounted for 99% of samples between September and mid-November.
The study also found that both variants disproportionately infected Black children, but especially the Omicron variant. More than a quarter (26%) of the children infected with Omicron were Black, but less than 15% of the children who had any encounter with the health care system during the same timeframe were Black.