The immunoassays used to measure anti-spike SARS-CoV-2 antibodies are widely available on the market. However, their performance in COVID-19 vaccinees is not yet adequately assessed. Our study provides a head-to-head comparison of five methods: Abbott’s S1-RBD IgG, Roche’s S1-RBD total antibody, Euroimmun’s S1 IgG, and DiaSorin’s TrimericS IgG and S1/S2 IgG assays. Testing was performed in one hundred vaccinated subjects, at eight timepoints over eight months after vaccination. The results differed substantially between methods; however, they correlated strongly and demonstrated the individuals’ responses to both doses of vaccination and the waning of humoral immunity after eight months. Importantly, we encountered a high percentage of results above the assay-specific upper quantitation limit (UQL) for undiluted samples. This was the most pronounced for the Roche’s and Euroimmun’s assays. The Abbott’s assay showed the lowest percentage of results above the UQL. We also attempted to find a common way to establish antibody concentrations that might be classified as high. However, this resulted in between 10% and 100% of such results for different methods on day 240′. This highlights the need for an assay-specific approach for adjusting the cut-offs that may indicate COVID-19 immunity.

This study pictures the humoral response of 100 vaccinees to Pfizer/BioNTech COVID-19 vaccine over a year, with particular focus on the influence of a booster shot administered around 10 months after the primary immunization. The response to the vaccination was assessed with Diasorin’s SARS-CoV-2 TrimericSpike IgG. Abbott’s SARS-CoV-2 Nucleocapsid IgG immunoassay was used to identify SARS-CoV-2 contact, even asymptomatic. In contrast to the gradual decline of the anti-spike IgG between 30 and 240 days after the first dose, an increase was noted between days 240 and 360 in the whole cohort. However, a statistically significant rise was seen only in boosted individuals, and this effect of the booster decreased over time. An increase was also observed in non-boosted but recently infected participants and a decrease was reported in non-boosted, non-infected subjects. These changes were not statistically significant. On day 360, a percentage of new SARS-CoV-2 infections was statistically lower in the boosted vs. non-boosted subgroups. The booster immunization is the most efficient way of stimulating production of anti-spike, potentially neutralizing antibodies. The response is additionally enhanced by the natural contact with the virus. Individuals with a low level of anti-spike antibodies may benefit the most from the booster dose administration.

Background. respiratory tract infections (rtis) constitute the most common reason for pediatric patients to report to primary care facilities. additionally, rtis are also a significant problem among hospitalized patients. due to the lack of specificity in the observed symptoms, rtis cause both diagnostic and therapeutic difficulties. Objectives. the aim of our study was to explain the causes of rtis in the pediatric population and to provide guidelines to facilitate diagnosis. Material and methods. in the study, the authors analyzed available literature dealing with the possibility of laboratory diagnosis and the results of treatment used in children with rtis. Results. in pediatric patients, rtis are mainly caused by viruses and occur seasonally during the autumn-winter period. there are certain factors, such as physiological distinctness resulting from developmental immaturity of the body, genetically determined diseases and specific diseases occurring during childhood, which contribute to the incidence of rtis. moreover, factors depending on the mother and the growth environment also significantly affect the incidence of rtis in children. Conclusions. available knowledge concerning the seasonality of the occurrence of individual pathogens and the differences in symptoms may facilitate an initial diagnosis. however, lower respiratory tract infections, and severe infections in particular, require the use of specific diagnostic tests which allow for both the identification of the etiological factors and the implementation of targeted treatment. the CoVid-19 pandemic has highlighted the difficulties in the diagnosis and therapy of rtis in pediatric patients, as well as the need to develop more sensitive diagnostic tools and a more effective treatment.