SARS-CoV-2 (severe acute respiratory syndrome coronavirus type 2) is a novel virus that has been identified as a causal agent of COVID-19,  an emergent infectious disease which brought about a new pandemic in the twenty-first century. The immune responses and clinical features of individuals infected with SARS-CoV-2 have not yet been fully described. Thus, in this study, we compare the seroprevalence and define the correlation between symptoms and serological results in the first COVID-19 cluster in the city of Konjic, Bosnia and Herzegovina. Of the total number, 93% of RT-PCR positive participants had positive IgG serology and 75% of them developed symptoms of COVID-19. We found that there was no significant alteration in specific IgG (p = 0.504) antibody levels during the 1-year period after COVID-19. Our results indicate that symptomatic COVID-19 patients have a higher rate of seroconversion (p < 0.01). The IgG seroconversion was correlated with high fever (p = 0.002) and headache (p = 0.007), suggesting that these symptoms could be considered as indicators of a better immune response. This study has demonstrated persistence of sustained levels of specific SARS-CoV-2 antibodies after recovering from COVID-19 infection. However, in order to gain a better insight into the immune response to SARS-CoV-2, further systematic studies should be focused on quality and longevity analyses.

Objective Cystatin C (Cys-C) concentration has not been examined sufficiently among healthy newborn population, particularly in terms of reference values. This study aimed to establish gender-, postnatal age- and birth weight-specific Cys-C concentration for healthy term newborns. Its objective was also to examine if there were any differences between our measured concentration and the reference interval established by the CALIPER study. Methods Serum samples from a total of 90 healthy term newborns were used to determine Cys-C concentration. Cys-C was measured within first three days of birth using particle-enhanced turbidimetric immunoassay (PETIA) on the Architect plus ci8200 analyzer. Results Median concentration of the Cys-C was 2.05 mg/L. There were no statistically significant differences in Cys-C concentration regarding gender (p=0.779), birth weight (p=0.505), postnatal age (p=0.512) or Apgar score (p=0.799). The value of the 2.5th and 97.5th percentile for Cys-C concentrations for girls was 0.93–3.15 mg/L and for boys it was 1.5–3.36 mg/L. Conclusion Cys-C concentration in healthy term newborns does not depend on gender, birth weight, postnatal age, or Apgar score. Our measured concentration range of CyS-C in healthy newborns turned out to be slightly wider than the interval determined in the CALIPER study.

Background: Cytomegalovirus (CMV) seroprevalence varies between 60% in developed countries and 100% in developing countries. The aim of this study was to assess CMV seroprevalence in representative sample of children in Bosnia and Herzegovina and to identify possible factors associated with CMV. Methods: Blood samples and surveys were collected from 253 children at the