COVID-19 vaccine uptake among children and adolescents in Norway: A comprehensive registry-based cohort study of over 800,000 individuals.

Factors related with COVID-19 vaccine uptake in children and adolescents in Norway remain unclear, despite this being useful knowledge for future pandemic preparedness. This study aimed to comprehensively examine individual and familial factors associated with vaccine uptake in children and adolescents in Norway. We utilized nationwide registry-data from various health registries and Statistics Norway, encompassing all children and adolescents living in Norway during the pandemic, until 31-Dec-2022. Vaccine uptake is defined as receiving at least one dose of COVID-19 vaccine. We employed a forward stepwise logistic regression model and a random forest machine-learning algorithm to explore the relationship between vaccine uptake and socio-cultural, demographic, and health-related factors. We included 423,548 5-11-year-olds, 269,830 12-15-year-olds, and 120,854 16-17-year-olds. Vaccine uptake in these three groups was respectively 2.6 %, 73.3 %, and 87.3 %. Factors associated with vaccine uptake varied by age group. In youngest children, immigrant background (Odds-ratio (OR) = 1.58, 95 % confidence interval (CI) (1.14-2.19)), born extremely preterm (OR = 2.38, 95 % CI (1.60-3.54)), having risk of severe COVID-19 (OR = 5.40, 95 % CI (4.69-6.23) and maternal COVID-19 vaccination (OR = 6.34, 95 % CI (5.35-7.53)) were positively associated with vaccine uptake. The latter two factors were also strongly, positively associated with vaccine uptake in 12-15-year-olds, while previous SARS-CoV-2 infection was negatively associated (OR = 0.12, 95 % CI (0.11-0.14). Similar findings were observed in 16-17-year-olds. COVID-19 vaccine uptake differed markedly by age group, and major associated factors included socio-demographics and parental COVID-19 vaccination status, prior SARS-CoV-2 infection, but also being born premature and having moderate or high risk of severe COVID-19.

Adherence to vaccination guidelines of patients with complete splenectomy in Norway, 2008-2020.

The spleen is responsible for blood filtration and mounting an immune response against pathogens. In some people the spleen must be surgically removed because of traumatic events or oncological and hematological conditions. These patients are at higher risk of developing diseases caused by encapsulated bacteria throughout their lives. Thus, immunisations are advised for splenectomised persons to prevent infection caused by Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae type b (Hib). This study assessed vaccination coverage (VC) among Norwegian patients with surgical asplenia. Using the Nomesco Classification of Surgical Procedures codes, patient information (age, sex, date of initial diagnosis and date of surgery) was acquired from the Norwegian Patient Registry. The National Immunization Register provided information on vaccination status and data of any subsequent invasive bacterial infections were obtained from the Norwegian Surveillance System for Communicable Diseases. From the total population of Norway, 3155 patients who had undergone complete splenectomy were identified. Of these, 914 (29.0%) had received at least one dose of pneumococcal conjugate vaccine (PCV), 1324 (42.0%) at least one dose of pneumococcal polysaccharide vaccine and 589 (18.7%) had received both. Only 4.2% of the patients had received two doses of a meningococcal ACWY conjugate vaccine, while 8.0% of 1467 patients splenectomised after 2014 had received at least two doses of a serogroup B meningococcal vaccine. The VC for Hib was 18.7%. Nearly all splenectomised children under the age of 10 were vaccinated with Hib and PCV as these vaccines are included in the childhood immunisation program. For all vaccines, VC decreased with age. Twenty-nine invasive bacterial infections were registered post-splenectomy in 25 patients. Vaccination according to national recommendations could have prevented at least 8 (28%) of these infections. Our study showed that efforts are required to increase VC of splenectomised individuals in Norway.