Pediatric coronavirus vaccine is only 51% effective in Omicron among 5-11-year-old children, a new study by Clalit Research Institute claims.
The country's largest healthcare provider finding contradicts Pfizer's estimations from October 2021, claiming the efficacy of vaccines was close to 91%.
The research included data from 94,728 vaccinated 5-11-year-old children, compared to 94,728 unvaccinated children from the same age group.
The study was conducted from November 23, 2021, to January 7, 2022, when the Omicron variant was prevalent in Israel. Researchers from Harvard University, the University of Padua, Italy, and the University of London took part in the study.
The results showed that the morbidity rate among vaccinated children was 51% lower compared to unvaccinated children, and the rate of symptomatic infection was 48% lower.
"The protection provided by the vaccine was not constant in all age groups in the study," the researchers said. "The data showed better protection was recorded in the younger age group (five to six years old) versus the older age group (10–11)."
Chief Innovation Officer at Clalit Health Services Prof. Ran Balicer said that previous studies showed high efficacy for the first doses of the vaccine against symptomatic infection of the Delta variant of COVID, among adolescents.
"The current study shows that vaccination of 5-11-year-old children has provided less protection against Omicron. It is difficult to determine what part of the decrease in protection from infection can be attributed to the reduced dose of the vaccine and what part can be attributed to the differences in the effectiveness of the vaccine against Omicron as opposed to the Delta variant."
"Reality is certainly more complex than it used to be," Blicer said. "The data is displayed to the public so that any parent can make an informed decision," he said.
This is not the first time it is revealed that the vaccine against COVID-19 is less effective in Omicron. An American study conducted in New York and published about five months ago suggested that Pfizer's vaccine efficacy was significantly reduced against infection and severe morbidity among children and adolescents during the Omicron wave. The researchers said that it may be necessary to increase the vaccination doses for children.
According to that study, the effectiveness of vaccines against infection among 5-11-year-olds dropped to 12% in late January compared to 68% in December. As for teenagers aged 12 to 17, vaccine effectiveness decreased to 51% in late January compared to 66% in mid-December.