To estimate the risk of hospitalization among reported cases of the Delta variant of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) compared with the Alpha variant in Norway, and the risk of hospitalization by vaccination status. A cohort study was conducted on laboratory-confirmed cases of SARS-CoV-2 in Norway, diagnosed between 3 May and 15 August 2021. Adjusted risk ratios (aRR) with 95% confidence intervals (CI) were calculated using multi-variable log-binomial regression, accounting for variant, vaccination status, demographic characteristics, week of sampling and underlying comorbidities. In total, 7977 cases of the Delta variant and 12,078 cases of the Alpha variant were included in this study. Overall, 347 (1.7%) cases were hospitalized. The aRR of hospitalization for the Delta variant compared with the Alpha variant was 0.97 (95% CI 0.76–1.23). Partially vaccinated cases had a 72% reduced risk of hospitalization (95% CI 59–82%), and fully vaccinated cases had a 76% reduced risk of hospitalization (95% CI 61–85%) compared with unvaccinated cases. No difference was found between the risk of hospitalization for Delta cases and Alpha cases in Norway. The results of this study support the notion that partially and fully vaccinated cases are highly protected against hospitalization with coronavirus disease 2019.

Background: The prevalence of Enterobius vermicularis in neighboring countries of Norway show large variation. The goal of this study was to investigate the prevalence among Norwegian children and possible risk factors. Methods: The children were participants in “Environmental Triggers of Type 1 Diabetes: the MIDIA study.” The study involved 2 groups with different genetic risks of type 1 diabetes: A high-risk group carries the Human Leukocyte Antigen genotype conferring the highest risk for type 1 diabetes and a nonhigh-risk group consisting of children without this genotype. Scotch tape samples were collected on 3 consecutive days and examined by light microscopy. Results: A total of 18% (72/395) of children were positive for E. vermicularis. The highest prevalence (34%) was in children 6–11 years of age. Only 2 children were prior known positives. Increased number of siblings was linked to more infections, and there were fewer infections in the children with the high-risk genotype. Conclusion: E. vermicularis is a common parasite in Norwegian children. The likelihood of E. vermicularis infection depends on family size and prevalence increases with age. The reduced number of infections in the children carrying the high-risk genotype for type 1 diabetes is intriguing and should be investigated further.

Objective: To evaluate risk factors for severe disease in children under 59 months of age hospitalized with respiratory syncytial virus (RSV) infection.Study design: We prospectively enrolled 1,096 cases of laboratory confirmed RSV infection during three consecutive RSV seasons in 2015–2018. Potential risk factors for severe disease were retrieved through patient questionnaires and linkage to national health registries. Need for respiratory support (invasive ventilation, bi-level positive airway pressure, or continuous positive airway pressure), and length of stay exceeding 72 h were used as measures of disease severity. Associations were investigated using multivariable logistic regression analyses. Multiple imputation was used to avoid bias and inference induced by missing data.Results: Risk factors associated with a need for respiratory support included age younger than 3 months of age [aOR: 6.73 (95% CI 2.71–16.7)], having siblings [aOR: 1.65 (95% CI 1.05–2.59)] and comorbidity [aOR: 2.40 (95% CI 1.35–4.24)]. The length of hospital stay >72 h was significantly associated with being younger than 3 months of age [aOR: 3.52 (95% CI 1.65–7.54)], having siblings [aOR: 1.45 (95% CI 1.01–2.08)], and comorbidity [aOR: 2.18 (95% CI 1.31–3.61)]. Sub-group analysis of children younger than 6 months of age confirmed the association between both young age and having siblings and the need for respiratory support.Conclusion: In a large cohort of children <59 months hospitalized with RSV infection, young age, comorbidity, and having siblings were associated with more severe disease.

Background: SARS-CoV-2 reinfection rates have been shown to vary depending on the circulating variant, vaccination status and background immunity, as well as the time interval used to identify reinfections. This study describes the frequency of SARS-CoV-2 reinfections in Norway using different time intervals and assesses potential factors that could impact the risk of reinfections during the different variant waves. Methods: We used linked individual-level data from national registries to conduct a retrospective cohort study including all cases with a positive test for SARS-CoV-2 from February 2020 to January 2022. Time intervals of 30, 60, 90 or 180 days between positive tests were used to define potential reinfections. A multivariable Cox regression model was used to assess the risk of reinfection in terms of variants adjusting for vaccination status, demographic factors, and underlying comorbidities. Results: The reinfection rate varied between 0.2%, 0.6% and 5.9% during the Alpha, Delta and early Omicron waves, respectively. In the multivariable model, younger age groups were associated with a higher risk of reinfection compared to older age groups, whereas vaccination was associated with protection against reinfection. Moreover, the risk of reinfection followed a pattern similar to risk of first infection. Individuals infected early in the pandemic had higher risk of reinfection than individuals infected in more recent waves. Conclusions: Reinfections increased markedly during the Omicron wave. Younger individuals, and primary infections during earlier waves were associated with an increased reinfection risk compared to primary infections during more recent waves, whereas vaccination was a protective factor. Our results highlight the importance of age and post infection waning immunity and are relevant when evaluating vaccination polices.

Learning from the COVID-19 pandemic and considering the effects of this pandemic, we provide recommendations that can guide towards sustainable RSV surveillance with the potential to be integrated into the broader perspective of respiratory surveillance. https://bit.ly/40TsO0G

Using individual-level national registry data, we conducted a cohort study to estimate differences in the length of hospital stay, and risk of admission to an intensive care unit and in-hospital death among patients infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant, compared with patients infected with Delta variant in Norway. We included 409 (38%) patients infected with Omicron and 666 (62%) infected with Delta who were hospitalised with coronavirus disease 2019 (COVID-19) as the main cause of hospitalisation between 6 December 2021 and 6 February 2022. Omicron patients had a 48% lower risk of intensive care admission (adjusted hazard ratios (aHR): 0.52, 95% confidence interval (CI): 0.34–0.80) and a 56% lower risk of in-hospital death (aHR: 0.44, 95%CI: 0.24–0.79) compared with Delta patients. Omicron patients had a shorter length of stay (with or without ICU stay) compared with Delta patients in the age groups from 18 to 79 years and those who had at least completed their primary vaccination. This supports growing evidence of reduced disease severity among hospitalised Omicron patients compared with Delta patients.