Heterogeneity in testing for infectious diseases

Testing strategies have varied widely between nation states during the COVID-19 pandemic, in intensity as well as methodology. Some countries have mainly performed diagnostic testing while others have opted for mass-screening for the presence of SARS-CoV-2 as well. COVID passport solutions have been introduced, in which access to several aspects of public life requires either testing, proof of vaccination or a combination thereof. This creates a coupling between personal activity levels and testing behaviour which, as we show in a mathematical model, leverages heterogeneous behaviours in a population and turns this heterogeneity from a disadvantage to an advantage for epidemic control

Complement defects in patients with chronic rhinosinusitis.

The complement system is an important part of our immune system, and complement defects lead generally to increased susceptibility to infections and autoimmune diseases. We have studied the role of complement activity in relation with chronic rhinosinusitis (CRS), and more specifically studied whether complement defects collectively predispose individuals for CRS or affect CRS severity. The participants comprised 87 CRS patients randomly selected from the general population, and a control group of 150 healthy blood donors. The CRS patients were diagnosed according to the European Position Paper on Rhinosinusitis and nasal Polyps criteria, and severity was evaluated by the Sino-nasal Outcome Test-22. Serum samples were analysed by ELISA for activity of the respective pathways of complement, and subsequently for serum levels of relevant components. We found that the frequency of complement defects was significantly higher among CRS patients than among healthy control subjects. A majority of Mannan-binding lectin deficient CRS patients was observed. The presence of complement defects had no influence on the severity of subjective symptoms. Our studies show that defects in the complement system collectively may play an immunological role related to the development of CRS. However, an association between severity of symptoms and presence of complement defects could not be demonstrated

Serum concentrations of IgA, MBL and CL-11.

<p><b>A</b>) IgA serum concentration (mg/ml). One CRS patient with a suspected IgA deficiency (<0.021 mg IgA/ml) was identified. <b>B</b>) Serum levels of MBL (ng/ml) in the 15 patients with non-detectable MBL pathway activity (triangles). Positive controls illustrated with serum levels of MBL in five genotyped individuals homozygous (circles) or heterozygous (squares) for structural MBL wild type alleles. <b>C</b>) Serum levels of CL-11 (ng/ml) among CRS patients. No CL-11 deficient patients were found.</p

Activity of complement pathways in patients with chronic rhinosinusitis (CRS).

<p>The dotted lines indicate the lower cut-off values for normal activity of the given pathway. The cut-off values for the classical, alternative, and Ficolin lectin pathway were defined from the lower limit of a 95% confidence interval. For the MBL lectin pathway the cut-off value was defined as the lowest activity level measured in MBL genotyped donors with at least one structural wild type allele.</p

Distribution of severity of symptoms.

<p>The severity of symptoms was divided based on the total SNOT-22 score.</p

Comparative activity analysis of CRS patients with a potential defect.

<p>A lack of functional capacity of the MBL lectin pathway in 15 patients was observed. Patient no. 3 was slightly below the cut-off value in the classical pathway. Patient no. 67 was substantially below the cut-off value in both the classical and Ficolin lectin pathway. The lowest Ficolin lectin pathway activity was measured in patient no. 80, who together with patient no. 88 and 90 had alternative pathway activities marginally below the cut-off value.</p