Intracranial sinogenic and otogenic complications and high-grade orbital complications of sinusitis in children are rare, but case numbers appeared to increase after COVID-19 health measures were lifted. As similar trends were reported internationally, we conducted a multicenter retrospective case series to evaluate this “perceived accumulation”. The study population included otherwise healthy children treated at eight participating centers from seven countries including a period from 2012 to 2023 for above-mentioned complications. Recorded parameters included age, diagnosis, timing, duration and type of inpatient therapy, as well as microbiological and virological findings, and differential blood count. A total of 289 data sets were received from the eight centers. Cases per semiannual increased significantly from 6 to 28 in the sinogenic and 3 to 12 in the otogenic cohort comparing pre- to post-pandemic period. Main patient characteristics were preserved. However, the number of surgical interventions per patient rose slightly in the post-pandemic sinogenic cohort. No association with acute COVID-19 infection was identified. In summary, intracranial sinogenic and otogenic complications in children rose significantly after the lifting of COVID-19-related restrictions. As immunity to respiratory viruses is not permanent, COVID-19 protective measures may have resulted in a lack of stimulation of the immune system, favoring the occurrence of superinfections. This highlights the importance of global respiratory infection research and surveillance programs, as well as open data sharing and maintaining vaccine development and use.