Vol 30, No 4 (2025)

Background: Severe COVID-19 (caused by SARS-CoV-2) is associated with profound immune dysregulation, primarily manifested as lymphopenia. It is essential to thoroughly describe and compare changes in T-cell subpopulation profile in patients with varying disease severity to identify prognostic markers and understand pathogenesis.

Aim: The study aimed to compare counts of the main T-cell subpopulations (CD3⁺, CD4⁺, CD8⁺) and their ratio in patients with moderate or severe cases of COVID-19 to identify immunological markers associated with disease progression.

Methods: This was a single-center, prospective, comparative, observational study in a cohort of 89 hospitalized patients with confirmed SARS-CoV-2 infection who provided informed consent. The patients were divided into two groups: 66 patients with moderate disease and 23 patients with severe disease who were on mechanical ventilation. The CD4⁺ and CD8⁺ T-cell counts were measured in whole blood using flow cytometry. The Mann–Whitney U test was used for statistical analysis.

Results: The patients with severe COVID-19 demonstrated significantly lower CD4⁺ and CD8⁺ T-cell counts than those with moderate disease (p < 0.001). The median CD4⁺ T-cell count in the severe disease group was 222 [135; 446] cells/μL, which was more than three times lower than in the moderate disease group (750 [470; 1061] cells/μL). The CD8⁺ T-cell count was substantially lower as well (98 [72; 275] cells/μL vs. 337 [238; 444] cells/μL). However, no statistically significant differences in the CD4⁺/CD8⁺ ratio were found between the groups (p = 0.073).

Conclusion: Severe COVID-19 is associated with profound concurrent suppression of both the helper and cytotoxic components of cellular immunity, without a significant shift in the CD4⁺/CD8⁺ ratio. CD4⁺ and CD8⁺ T-cell counts can serve as objective laboratory markers for risk stratification and assessment of COVID-19 severity, which is crucial for the timely treatment of these patients.

For several decades, avian influenza viruses have been considered a source of new variants with pandemic potential based on all known influenza pandemics to date. This review provides examples of human infections with various subtypes of avian influenza A viruses since 1997, when the first cases of human infection with highly pathogenic (H5N1) avian influenza viruses were reported in Hong Kong. In recent years, the World Health Organization has reported the largest number of human avian influenza virus infections in the Pacific region. An unusual outbreak of avian influenza A(H5N1) has been documented among cows and birds in the United States, with some farmers being infected as well. The article presents an analysis of infection risks, the properties and structure of strains, and their susceptibility to direct-acting antivirals. It also discusses vaccine development approaches, the strategy and tactics of vaccination within the WHO Pandemic Influenza Preparedness Framework and the Global Influenza Strategy.

Guillain–Barré syndrome is an acute and rapidly progressive autoimmune disease that affects the peripheral nervous system. The major manifestations are limb paresthesia, muscle weakness, and/or flaccid paralysis. The disease is often associated with previous infections, such as respiratory or gastrointestinal ones. During the COVID-19 pandemic, evidence emerged suggesting that over 30% of patients infected with SARS-CoV-2 presented with neurological symptoms. These symptoms may appear at various stages of the disease and include headache, muscle pain, nausea, vomiting, loss of smell (anosmia), and loss of taste (ageusia). However, COVID-19 can also cause more severe complications such as encephalomyelitis, acute myelitis, thromboembolic disorders, ischemic stroke, intracerebral hemorrhage, Guillain–Barré syndrome, Bell’s palsy, and rhabdomyolysis. Guillain–Barré syndrome is characterized by a rapid progression of muscle weakness that can lead to respiratory muscle paralysis and respiratory failure, requiring immediate medical intervention. The article reports a clinical case of Guillain–Barré syndrome associated with COVID-19. This case report emphasizes the importance of prompt diagnosis of neurological complications in patients with COVID-19 to improve prognosis and reduce the risk of long-term complications.

The editorial board of the journal "Epidemiology and Infectious Diseases" announces the retraction of the article " Immunological Effectiveness of Mass Vaccine Prevention Against Hepatitis B in the Framework of Realization of the Priority National Project "Health" in Some Regions of the Russian Federation," published in 2015;20(4) by Shulakova N.I. et al. (DOI: 10.17816/EID40845 EDN: UHYRUB).

The reason for retraction is simultaneous publication in another journal without the publishers’ consent. Similar article: Shulakova NI, Lytkina IN, Akimkin VG, et al. Immunological effectiveness of mass vaccination against hepatitis B within the framework of the priority national project "Health" in certain regions of the Russian Federation". Public Health and Life Environment – PH&LE. 2015;(6):39-43. EDN: UCHPWN. The editors found of the publication of a similar article through their own work procedures for assessing the journal's scientometric indicators. It was not possible to reliably determine to which journal the article was previously submitted using available methods. Therefore, a decision was made to retract the article from the journal "Epidemiology and Infectious Diseases".