Frequency and risk of SARS-CoV-2 reinfections in Norway: a nation-wide study, February 2020 to January 2022.

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.

Reporting of notifiable infectious diseases during the COVID-19 response. / Registrerte meldingspliktige smittsomme sykdommer under covid-19-responsen.

BACKGROUND: The Norwegian Surveillance System for Communicable Diseases (MSIS) is based on reporting of cases of 72 mandatory notifiable diseases by clinical microbiological laboratories and diagnosing physicians. The aim of our study was to investigate a potential temporal association between measures against COVID-19 in February-April 2020 and incidence of other infectious diseases reported to MSIS. MATERIAL AND METHOD: We compared the number of disease cases reported to MSIS during weeks 6-14 in 2020 with the median of cases reported in corresponding weeks during three previous years (2017-2019). RESULTS: Compared to the median of cases reported during corresponding weeks in three previous years, physicians and laboratories reported 47 % fewer cases (159 vs. 301) in week 12, 50 % fewer cases (131 vs. 261) in week 13, and 69 % fewer cases (77 vs. 252) in week 14. There was a reduction in the number of notifications of all included disease groups. INTERPRETATION: The observed decline in reporting of diseases other than COVID-19 may indicate a reduced risk of communicable diseases due to comprehensive advice and the requirement for social distancing. However, it is also possible that the sensitivity of the surveillance system was affected by increased resource use on COVID-19 cases management.

COVID-19 cases reported to the Norwegian Institute of Public Health in the first six weeks of the epidemic. / Covid-19 rapportert til Folkehelseinstituttet de første seks ukene av epidemien.

BACKGROUND: The first case of SARS-CoV-2 infection in Norway was confirmed on 26 February 2020. Following sharpened advice on general infection control measures at the beginning of the outbreak, extensive national control measures were implemented on 12 March, and testing was focused on those with severe illness. We describe the first six weeks of the outbreak in Norway, viewed in light of testing criteria and control measures. MATERIAL AND METHOD: We described all laboratory-confirmed cases of COVID-19 reported to three different surveillance systems under the Norwegian Institute of Public Health up to 5 April 2020, and compared cases reported up to 12 March with those reported from 13 March. RESULTS: By 12 March, 1 128 cases had been reported. Their median age was 47 years, 64 % were male, 66 % had travelled abroad, 6 % were hospitalised at the time of reporting, and < 1 % had died. The median age of the 4 742 cases reported from 13 March was 48 years, 47 % were male, 18 % had travelled abroad, 15 % were hospitalised, and 3 % died. INTERPETATION: The distribution of COVID-19 cases before and after 12 March reflects different phases of the outbreak. However, findings must be interpreted in the light of criteria for testing, testing activity, control measures and characteristics of surveillance systems.

Summary of available surveillance data on hepatitis C virus infection from eight Arctic countries, 2012 to 2014.

We summarised available hepatitis C virus (HCV) surveillance data for 2012-14 from Arctic/sub-Arctic countries/regions. We sent a HCV data collection template by email to public health authorities in all jurisdictions. Population statistics obtained from census sources for each country were used to estimate rates of reported acute and chronic/undifferentiated HCV cases. Seven countries with Arctic regions (Canada, Denmark, Finland, Greenland, Norway, Sweden and the United States, represented by the state of Alaska), including three Canadian territories and one province, as well as 11 Russian subnational Arctic regions, completed the data collection template. Data on acute HCV infection during 2014 was available from three Arctic countries and all Russian Arctic regions (rate range 0/100,000 population in Greenland, as well as Nenets and Chukotka Automous Okrugs (Russian subnational Arctic regions) to 3.7/100,000 in the Russian Republic of Komi). The rate of people with chronic/undifferentiated HCV infection in 2014 ranged from 0/100,000 in Greenland to 171.2/100,000 in Alaska. In most countries/regions, the majority of HCV-infected people were male and aged 19-64 years. Differences in surveillance methods preclude direct comparisons of HCV surveillance data between Arctic countries/regions. Our data can inform future efforts to develop standardised approaches to HCV surveillance in the Arctic countries/regions by identifying similarities/differences between the surveillance data collected.

Modelling the burden of hepatitis C infection among people who inject drugs in Norway, 1973-2030.

BACKGROUND: Lack of Hepatitis C virus (HCV) incidence data in (Norwegian) high-risk groups impedes the ability to make informed decisions on prevention measures. Thus we rely on modelling to estimate the incidence and burden of HCV infections. METHODS: We constructed a compartmental model for HCV infections in Norway among active and former people who inject drugs (PWIDs). We based yearly transition rates on literature. The model was fitted to absolute numbers of hepatitis C associated cirrhosis, hepatocellular carcinoma (HCC) and death from national data sources (2000-2013). We estimated the number (95%CI) of HCV infections, cirrhosis, HCC and death and disability adjusted life years (DALYs) due to HCV infections in Norway, 1973-2030. We assumed treatment rates in the projected period were similar to those in 2013. RESULTS: The estimated proportion of chronic HCV (including those with cirrhosis and HCC) among PWIDs was stable from 2000 (49%; 4441/9108) to 2013 (43%; 3667/8587). We estimated that the incidence of HCV among PWIDs was 381 new infections in 2015. The estimated number of people with cirrhosis, HCC, and liver transplant was predicted to increase until 2022 (1537 people). DALYs among active PWIDs estimated to peak in 2006 (3480 DALYs) and decrease to 1870 DALYs in 2030. Chronic HCV infection contributes most to the total burden of HCV infection, and peaks at 1917 DALYs (52%) in 2007. The burden of HCV related to PWID increased until 2006 with 81/100,000 DALYs inhabitants and decreased to 68/100,000 DALYs in 2015. CONCLUSION: The burden of HCV associated with injecting drug use is considerable, with chronic HCV infection contributing most to the total burden. This model can be used to estimate the impact of different interventions on the HCV burden in Norway and to perform cost-benefit analyses of various public health measures.

Economic Evaluation of Direct-Acting Antivirals for Hepatitis C in Norway.

PURPOSE: New direct-acting antiviral (DAA) drugs have revolutionized the treatment of hepatitis C in recent years. OBJECTIVE: Our objective was to analyse the cost effectiveness of combinations of different DAAs compared with ribavirin and peginterferon-α-2a, taking into account rebates from tender negotiations. METHODS: We used a compartmental model specifically developed for Norway to simulate hepatitis C and complications with and without different DAAs. All costs were based on Norwegian fees and estimates, estimating healthcare sector costs for the year 2016. We performed Monte Carlo simulations on uncertain input parameters to facilitate probabilistic sensitivity analyses. RESULTS: For patients diagnosed with genotype 1, the combination of paritaprevir, ritonavir, ombitasvir and dasabuvir was cost effective compared with eight other available alternatives, given a cost-effectiveness threshold of €70,000 per quality-adjusted life-year. For genotype 2, the combination of sofosbuvir and ribavirin was the most effective and cost-effective alternative for all patients. Among available alternatives for patients with genotype 3, sofosbuvir in combination with peginterferon and ribavirin was the most cost-effective alternative, although the combination of daclatasvir and sofosbuvir was somewhat more effective. CONCLUSIONS: For each of the hepatitis C genotypes 1, 2 and 3, there were combinations of DAAs that were cost effective in a Norwegian setting. As a result of recent tender negotiations in Norway, treating all diagnosed patients with hepatitis C with the most cost-effective DAAs will result in lower total expenditure on these medications compared with 2015.

Postpartum Depression Among Somali Women in Norway.

Postpartum depression (PPD) has been described as the most common complication experienced postpartum, affecting about 10-15 % of all new mothers. Factors like a history of mental illness, and experienced recent adverse life events has been associated with an increased risk for developing PPD. Immigrant women in Western countries have been found to have a marked higher prevalence of PPD compared to the general population. In Norway the prevalence of PPD in the general population has been found to be around 8-10 %, and among Pakistani immigrants a rate of 7.6 % was found. Somali people in Norway are the second largest immigrant group in Norway with a non-Western background. No study on PPD and associated factors among Somali women has been found in the literature. The aim of the study was to assess PPD and associated factors among Somali women in greater Oslo region, Norway. A cross-sectional survey was conducted; recruiting new mothers through all maternity wards in the Oslo region. Data was collected with interview-administrated questionnaires. PPD was assessed using Edinburgh Postnatal Depression Scale (EPDS), defining those scoring ≥10 to have a possible PPD. Of the 80 eligible women identified, 39 (49 %) consented to participate, and completed the study. Of the 39 respondents 3 (7.7 %) were assessed to have a possible PPD. Most important associated factors found were history of mental illness, having experienced technical assistance during delivery, self-rated health and experienced economical problems last 12 months. A low prevalence of PPD was found, and both the prevalence and its associated factors should be interpreted with caution. The associated factors do not have enough power to give any strength to the associations. However, some of the results can be used in develop new hypotheses with regard to PPD among Somali women as immigrants in a Western society.