Pfizer-BioNTech’s vaccine, Comirnaty, was approved by the US FDA for use in children aged five to 11 years in October 2021, and soon after the EMA (European Medicines Agency) also recommended that the drug be given to this age group in the European Union. Now, analysis of data collected by officials at the New York State Department of Health (USA) during the wave of the omicron variant has revealed that the protection provided by this vaccine against COVID-19 to children of five at 11 years of age it dropped drastically just one month after they received the complete vaccination schedule, although it did continue to protect against hospital admission in case of coronavirus infection.
Researchers and federal officials who have reviewed the data have attributed this loss of efficacy of Comirnaty in young children relative to those older than 11 years in part to the fact that they are given one-third the dose that adolescents receive 12 years and adults: 10 µg vs. 30 µg. The results of this analysis, which have been published in the MedRxiv repository (not peer-reviewed for publication in a scientific journal), are added to those obtained in clinical trials that show that this vaccine was not effective in children aged two to four. years, who received an even smaller dose.
“It’s disappointing, but not entirely surprising, given that this is a vaccine developed in response to an earlier variant,” said Dr. Eli Rosenberg, deputy director of science at the New York State Department of Health, who led the study. study. “It seems very distressing to see this rapid decline, but again everything is against omicron.” Despite this, he and other public health experts have said they recommend the vaccine for children because of the protection against severe COVID seen even in the new data set.
Regarding this study, the North American CDC said that data from many other states suggest that the problem is not the age of the children or the size of the dose, it is omicron. And they clarify that unvaccinated children aged 5 to 11 years were 1.3 times more likely to contract COVID-19 in January, at the height of the omicron increase, than vaccinated children. For youth ages 12 to 17, the unvaccinated were 1.5 times more likely to contract COVID-19 than their vaccinated peers that month.
The reduced dose of the vaccine could subtract effectiveness
Dr. Rosenberg and colleagues studied data from 852,384 children ages 12 to 17 and 365,502 children ages 5 to 11, who had been vaccinated between December 13, 2021, and January 31, 2022, the point maximum increase in infections per omicron. The effectiveness of the vaccine in preventing hospitalization decreased from 85% to 73% in older children, while in younger children, efficacy fell from 100% to 48%. Although it is important to note that these estimates have wide margins of error due to the fact that few children are hospitalized.
Vaccine effectiveness against SARS-CoV-2 infection was 67% in 12-year-olds, but only 11% in 11-year-olds
The calculations regarding protection against infection are more reliable and in this case it was estimated that the effectiveness of the vaccine against infection in older children was reduced from 66% to 51% and, in younger children, the drop was more drastic , falling to just 12% from 68%. The change was especially significant when comparing 11 and 12 year olds. For the week ending January 30, vaccine effectiveness against SARS-CoV-2 infection was 67% in 12-year-olds, but only 11% in 11-year-olds.
This has made experts think that the key may lie in the dose they receive, since the biological difference between the two ages is likely to be minimal, but while 12-year-olds were given 30 micrograms of the vaccine ( same dose as adults), 11-year-olds only received 10 micrograms.
These findings have shown that more information needs to be collected to determine the best dose, number and timing of vaccines given to children, Rosenberg said. Experts often revise the dosage and timing of pediatric vaccines as more evidence becomes available. But in this case, increasing the dose in children to stimulate the immune response may not be appropriate because there is evidence to suggest that it can cause high fever, a potentially dangerous side effect in young children.
Pfizer and BioNTech are now testing a third dose in children under 5 years of age and those between 5 and 11 years of age to see if, as in adults, a booster injection could significantly increase immunity, as studies in adults suggest that three doses of the vaccine conferred greater protection against the omicron variant than two doses. Another alternative may be a version of the vaccine designed to combat omicron, or one that includes a combination of several variants. Pfizer-BioNTech, Moderna, and Johnson and Johnson are testing versions of their specific omicron vaccines.
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