Human cells homozygous for rare loss-of-expression (LOE) TYK2 alleles have impaired, but not abolished, cellular responses to IFN-α/β (underlying viral diseases in the patients) and to IL-12 and IL-23 (underlying mycobacterial diseases). Cells homozygous for the common P1104A TYK2 allele have selectively impaired responses to IL-23 (underlying isolated mycobacterial disease). We report three new forms of TYK2 deficiency in six patients from five families homozygous for rare TYK2 alleles (R864C, G996R, G634E, or G1010D) or compound heterozygous for P1104A and a rare allele (A928V). All these missense alleles encode detectable proteins. The R864C and G1010D alleles are hypomorphic and loss-of-function (LOF), respectively, across signaling pathways. By contrast, hypomorphic G996R, G634E, and A928V mutations selectively impair responses to IL-23, like P1104A. Impairment of the IL-23–dependent induction of IFN-γ is the only mechanism of mycobacterial disease common to patients with complete TYK2 deficiency with or without TYK2 expression, partial TYK2 deficiency across signaling pathways, or rare or common partial TYK2 deficiency specific for IL-23 signaling.

Objective: The studies on children with COVID-19 are very limited. The aim of this study is to reveal the effect of serum 25-hydroxy vitamin D level on clinical and laboratory parameters. Materials and Methods: The study included 74 children (35 boys and 39 girls) diagnosed with COVID-19. The retrospective data were obtained from the file records of the patients. Seventy-four patients were divided into 3 groups (group 1, deficient; group 2, insufficient; and group 3, sufficient) according to their serum 25-hydroxy vitamin D levels. Results: The mean age of all patients was 113.25 ± 64.55 months. The mean leucocyte count was substantially higher in group 3 compared to groups 1 and 2 (P = .05 and P = .002, respectively). The mean lymphocyte and platelet count in group 3 was remarkably higher than both groups 1 and 2 (P = .001 and P = .002; and P = .04 and P = .01, respectively). The mean serum parathyroid hormone concentration in group 1 was markedly higher than both groups 2 and 3 (P=.003 and P = .002, respectively) while the mean serum 25-hydroxy vitamin D level in group 1 was remarkably lower than both groups 2 and 3 (P=.001 and P=.001, respectively). Serum 25-hydroxy vitamin D concentrations were positively correlated with leucocyte, lymphocyte, and platelet counts (r=0.221, P=.05; r=0.396, P=.001; and r=0.249, P=.03, respectively) while there was a negative correlation with parathyroid hormone concentrations (r=−0,436, P=.001). Conclusion: This study suggests that COVID-19 has a benign course in children and that serum 25-hydroxy vitamin D concentration may have a role in the lymphocyte count. Cite this article as: Ozden A, Doneray H, Hafize Erdeniz E, Altinkaynak K, Igan H. Clinical and Laboratory Findings by Serum Vitamin D Levels in Children with COVID-19. Eurasian J Med., 2022;54(3), 285-291.

Understanding SARS-CoV-2 seroprevalence among health care personnel is important to explore risk factors for transmission, develop elimination strategies and form a view on the necessity and frequency of surveillance in the future. We enrolled 4927 health care personnel working in pediatric units at 32 hospitals from 7 different regions of Turkey in a study to determine SARS Co-V-2 seroprevalence after the first peak of the COVID-19 pandemic. A point of care serologic lateral flow rapid test kit for immunoglobulin (Ig)M/IgG was used. Seroprevalence and its association with demographic characteristics and possible risk factors were analyzed. SARS-CoV-2 seropositivity prevalence in health care personnel tested was 6.1%. Seropositivity was more common among those who did not universally wear protective masks (10.6% vs 6.1%). Having a COVID-19-positive co-worker increased the likelihood of infection. The least and the most experienced personnel were more likely to be infected. Most of the seropositive health care personnel (68.0%) did not suspect that they had previously had COVID-19. Health surveillance for health care personnel involving routine point-of-care nucleic acid testing and monitoring personal protective equipment adherence are suggested as important strategies to protect health care personnel from COVID-19 and reduce nosocomial SARS-CoV-2 transmission.