In the supplementary material to an FDA preprint noting a Safety Signal for seizures and convulsions in kids under age 6, it shows that the baseline (including both jabbed kids and unjabbed kids) had more than doubled from 2020 to 2022.
The steepest rise came from the claims database at Carelon Research in kids from age 2 to age 4, where the baseline rate for 2020 had been 234.35 per 100,000 person-years, but the 2022 baseline was 551.18 per 100,000 person-years — which was 2.35 times higher than 2020.
Because of the general decline in health for all kids in the USA, the FDA researchers noted how, when the 2022 baseline was used, even the risk among jabbed kids only was no longer significantly elevated.
But that just means that every kid in the USA is worse off now than back in 2020.
Reference
[Supplementary Material to the FDA study on Safety Signals in kids] — Supplement. Safety of Monovalent BNT162b2 (Pfizer-BioNTech), mRNA-1273 (Moderna), and NVX-CoV2373 (Novavax) COVID-19 Vaccines in US Children Aged 6 months to 17 years. https://www.medrxiv.org/content/10.1101/2023.10.13.23296903v1.supplementary-material
Looks like catching up of previous immunizations that have crowded the childhood vaccination schedule over the last decade has created enough seizures to render the excessive the seizures caused by the covid-19 vaccines as failing to achieve statistical significance. If we were to exclude the covid-19 vaccine induced seizures from the background, statistical significance might be possible. If we used only people who have never received a vaccine for anything, the picture would be radically different.