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Six-year-old gets her second vaccination in San Francisco (icon image)
Photo: Santiago Mejia/San Francisco Chronicle/Getty Images
Children between the ages of five and eleven are less well protected against infection with the omicron variant of the coronavirus after vaccination than children between the ages of 12 and 17.
This is the result of a study by the New York State Department of Health, which was published as a preprint on Monday.
So far, only the Biontech/Pfizer product has been approved for this age group in the USA and Europe.
A lower dose is administered to children aged five to eleven than to those over 12: while older children and adolescents receive two adult doses for full immunization, younger children only receive a third of the dose.
The data suggest that the clear differences in effectiveness could be due to the lower dosage in the smaller children.
This becomes particularly clear when you look closely at the age limit, where the younger people receive the lower dose and those who are only a little older already receive the higher dose: According to this, the effectiveness against an infection with the omicron variant in the eleven-year-olds examined was last January -week at only around 11 percent.
For 12-year-olds, it is given as around 67 percent.
"Notable difference"
"The difference between the two age groups is remarkable," says Florian Krammer, immunologist at the Icahn School of Medicine at Mount Sinai Hospital, the "New York Times".
The biological difference between 11 and 12-year-olds is minimal, but the 11-year-old received only 10 micrograms of the vaccine, while the 12-year-old received 30 micrograms.
"That's very interesting because it suggests that it's the dose that makes the difference," says Krammer.
"The question is what the solution is."
The authors of the study themselves see the lower dosage as the main reason for the rapid decrease in vaccination protection in children under 12 years of age.
The comparison of eleven and 12-year-olds suggests that.
"The 12-year-olds had the highest vaccination effectiveness of all age groups," says the study.
"That's probably because of how small she is in relation to the dose of the vaccine and because she was vaccinated quite recently."
In total, the scientists examined more than one million fully vaccinated children between December 13, 2021 and January 30, 2022 in the state of New York.
In the 12 to 17 year olds, the effectiveness of the vaccination fell from 66 to 51 percent during the study period.
The difference was even clearer in the five to eleven year olds: in mid-December the vaccination was still 68 percent effective against an infection with Sars-CoV-2, at the end of January only 12 percent.
Protection from hospitalization also seems to decrease more quickly in younger children than in older ones.
In mid-December, 85 percent of 12 to 17-year-olds were still protected from having to go to the hospital with Covid 19 disease, but only 73 percent at the end of January.
For five to eleven year olds, protection fell from 100 percent to just 48 percent within six weeks.
However, the figures for hospitalization are of limited significance, as overall only very few children with Covid-19 had to be hospitalized.
"It's disappointing, but not entirely surprising," Eli Rosenberg, deputy director of science at the New York Department of Health, told the New York Times about the study results.
Rosenberg led the investigation.
"It looks very worrying to see this rapid decline, but it's a vaccine that was developed against earlier variants."
The results show the importance of finding out more information about the best doses for children, the number of vaccinations and the intervals, Rosenberg said.
The data also showed that vaccinations are only one effective tool in combating the pandemic – alongside wearing masks and social distancing.
But wearing masks and the rules of distance and hygiene are often difficult for small children to comply with.
Infections introduced in schools and day-care centers therefore spread particularly quickly.
Consequently, it is above all the younger age groups in which the incidences are currently highest, and from a purely mathematical point of view it is to be expected that there will also be a high number of breakthrough infections here.
So far, the little ones have been left empty-handed
And yet another reason could explain why the vaccination effectiveness in this age group decreases so much: In adults it has already been observed that the omicron variant can bypass the vaccination protection, but the antibody levels rise again after a third vaccination and thus better protection bid against omicron.
However, neither in the USA nor in Europe is the booster vaccination currently recommended for under 12-year-olds, but it is for over-12-year-olds.
In the study, 12.5 percent of 12- to 17-year-olds were boosted, which probably contributed to additional protection.
Despite the sobering evaluation, the US data also shows that the vaccination protects children of all ages from severe courses.
In addition, there is increasing evidence that the vaccinations also reliably protect against more serious consequences of the virus, such as Pims or Long Covid.
However, no vaccine has yet been approved for children under the age of five.
Biontech/Pfizer is currently testing its drug in children between the ages of six months and four years.
However, the results are a long time coming, as the low dosage does not yet produce the desired immune response.
The companies are now relying on a third vaccination for the very young.
Biontech/Pfizer are expecting results in early April.
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