In yet another turning point in the debate about the best way to protect children against the coronavirus, researchers reported Wednesday that the COVID vaccine has reduced hospitalizations among children 12 and older during the latest omicron surge. provided little protection against.
The vaccine’s effectiveness against hospitalization remained stable in children 5 to 11 years of age, however, and in adolescents 12 to 18 years of age, two doses of the vaccine were highly protective against serious illness requiring life support .
But the effectiveness of hospitalization for less severe disease in these children dropped to only 20%. The findings were published in The New England Journal of Medicine.
The data are broadly consistent with studies showing that, across all age groups, vaccines lost most of their potency against Omicron type infections but still prevented serious illness and death.
While any hospitalization is troubling, it is reassuring that vaccines still protect children from the worst consequences of infection, said Dr Manish Patel, a researcher at the Centers for Disease Control and Prevention who led the study. .
Of the teens in the study who were critically ill, 93% had not been vaccinated, and most had at least one underlying condition, Patel said. “I think the big take-home message is that with the simple act of immunization, you can prevent the most severe disease in most children,” he said.
As of March 23, only 1 in 4 children aged 5-11 and more than half of adolescents 12-17 in the United States were fully vaccinated. Those percentages have barely risen over the past few months.
For some parents still debating vaccination, the decision is complicated by the seeming backlash of the coronavirus. Cases and deaths have fallen to their lowest levels in a year, and no one yet knows whether Omicron’s BA.2 subvariant will bring about another wave.
Some parents, considering their children’s exposure to COVID, have been reluctant to vaccinate them from the start. But while children are far less likely to become seriously ill than adults, many of them were hospitalized during the Omicron boom more than at any other time in the pandemic.
In the new study, researchers analyzed medical records and interviewed parents of children aged 5 and older who had been hospitalized for COVID. They excluded children who had tested positive for coronavirus but were hospitalized for other reasons.
Because relatively few children are hospitalized for COVID, researchers were only able to identify 1,185 children, comparing them to 1,627 others who did not have COVID. Among those hospitalized for COVID, 291 got life support and 14 died.
The study included data from 31 hospitals in 23 states, and spanned from July 1 to December 18, 2021, when the Delta variant was circulating, and December 19 to February 17, when the Omicron variant was dominant. During the delta period, the effectiveness of hospitalization in adolescents up to 44 weeks after vaccination was over 90%.
However, during the omicron surge, those numbers for protection from hospitalization fell sharply to about 40%, regardless of the time since vaccination.
When the researchers analyzed the data by severity of illness, they found that the vaccine’s effectiveness against serious illness among hospitalized adolescents was 79 percent, but fell to 20 percent for less severe disease.
The new study is the first to look at the vaccine’s effectiveness in relation to disease severity in hospitalized patients. Eli Rosenberg, deputy director of science at the New York State Department of Health, said it is possible that this trend is visible in adult patients as well, if they are analyzed in a similar way.
“It’s interesting to split with the critical, non-critical,” he said. “It definitely adds a new layer.”
In children aged 5 to 11 years, complete vaccination had an effectiveness of 68% compared to overall hospitalization. Those data were collected during the Omicron surge, as these children only became eligible for vaccination on November 2. There were too few to analyze effectiveness by disease severity.
About 78% of all adolescents hospitalized in the study and 82% of young children had one or more underlying medical conditions, such as obesity, autoimmune diseases or respiratory problems including asthma.
The study suggests the vaccine protected most of these children from the worst outcomes, said former acting chief scientist of the Food and Drug Administration, Dr. Luciana Borio said.
“This really validates the importance of vaccines for children 5 and older, and especially for those who are immunocompromised or have underlying medical conditions,” she said.
The Omicron version may partially evade immune protection, so it’s not surprising that the vaccines didn’t do as well as the delta version, she and others said. Another recent study showed that in adolescents aged 12 to 17 years, even two doses of the vaccine provided virtually no protection against moderate disease caused by the Omicron variant. (Booster doses are now recommended for all Americans age 12 and older.)
The large discrepancy in vaccine effectiveness between those who needed life support and those who did not may be due to the wide range of symptoms for which the children were hospitalized. About 1 in 4 teens in the study required life-supporting interventions such as mechanical ventilation or extracorporeal membrane oxygenation.
Dr. Marietta Vazquez, an infectious disease specialist at Yale School of Medicine who was not involved in the study, said that, in her experience, the majority of children hospitalized during an omicron surge recovered quickly.
“The children we saw were admitted – they were either very, very sick, or they were admitted mostly because they were infected and had a high fever or had low oxygen saturation,” she said.
Parents were also keen to bring young children to the hospital during the Omicron boom, Vazquez said: “There is such concern and fear about COVID.”
Some researchers have theorized that the decline in vaccine protection among adolescents resulted from a decrease in effectiveness over time – that is, adolescents were not well protected during omicron surges because of the much longer time since their vaccination. It had passed
But the new study found that the vaccine’s effectiveness against the Omicron variant was 43% by 22 weeks after vaccination, and 38% between 23 and 44 weeks. Lower immunity appears to be less of a factor than the variant.
“It looked like it was more Omicron related,” Patel said.
Most of the vaccinated teens in the new study received just two doses. There weren’t enough people who received a third dose to evaluate its benefit, but a previous study suggested that a booster shot significantly improved protection against moderate disease in this age group, as did adults. Is.
“I really think kids should get three doses, and I expect that number to go up,” said Akiko Iwasaki, an immunologist at Yale University. Only about 14% of children 12 years of age and older have received a booster dose.
Apoorva Mandavilli@c.2022 The New York Times Company
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