Post-COVID syndrome in children: whether a change in lymphocyte count is a risk factor for its development?




COVID-19, Post-Acute COVID-19 syndrome, children, lymphocytes, adaptive reactions


The aim of the study: to find risk factors for post-COVID syndrome formation based on the analysis of the dynamic leukocyte count, the relative and absolute blood lymphocyte contents.

Materials and methods. A retrospective analysis of medical records of children, aged 10–17 years, who were hospitalized during the second wave of the pandemic (January – July 2021) to the CNE “Lviv Regional Children’s Clinical Hospital “Ohmatdyt” with a diagnosis of moderate COVID-19. A total of 46 children were selected, among them 26 children (post-COVID(-) group), who had no symptoms after COVID-19 and 20 children (post-COVID(+) group) who described various complaints related to disfunction of different organ systems, which affected a normal child’s life.

Results. All children from the post-COVID(+) group complained of fatigue, about a third of children – headache (30 %), which were not observed before the disease, quarter of children (25 %) had problems with concentrating, one fifth (20 %) – periodically felt unmotivated anxiety. Analysis of the leukocytosis dynamics, absolute and relative lymphocytosis in the control after one week ±2 days revealed no significant changes in these indicators in the post-COVID(-) group of children. While in the post-COVID(+) group, a slight increase in leukocytosis (from 3.9 × 109/L to 4.05 × 109/L, P = 0.13) was accompanied by a significant decrease in the number of lymphocytes, both relative (from 27 % to 16 %, P = 0.002) and absolute (from 1.51 × 109/L to 0.51 × 109/L, P = 0.001).

Conclusions. Patients with persistent lymphopenia or hyperlymphocytosis (one week ±2 days) during acute period of COVID-19 represent a “vulnerable cohort” concerning long-term persistence of symptoms, including severe asthenia. The tendency towards normalization of lymphocyte number can be considered as a protective factor for the formation of post-COVID syndrome, while the negative dynamics or its absence – as a risk factor for prolonged persistence of symptoms.

Author Biographies

O. L. Lychkovska, Danylo Halytsky Lviv National Medical University, Ukraine

MD, PhD, DSc, Professor, Head of the Department of Propaedeutic Pediatrics and Medical Genetics

D. I. Kvit, Communal Non-commercial Establishment of the Lviv Regional Council “Lviv Regional Children’s Clinical Hospital “Ohmatdyt”, Ukraine

MD, Director

I. Yu. Kulachkovska, Danylo Halytsky Lviv National Medical University, Ukraine

MD, PhD, Associate Professor of the Department of Propaedeutic Pediatrics and Medical Genetics

О. M. Sadova, Danylo Halytsky Lviv National Medical University, Ukraine

MD, PhD, Associate Professor of the Department of Propaedeutic Pediatrics and Medical Genetics

L. Ya. Zhyvko, Danylo Halytsky Lviv National Medical University, Ukraine

MD, Assistant of the Department of Propaedeutic Pediatrics and Medical Genetics

М. I. Dats-Opoka, Danylo Halytsky Lviv National Medical University, Ukraine

MD, PhD, Associate Professor of the Department of Propaedeutic Pediatrics and Medical Genetics

N. S. Kosmynina, Danylo Halytsky Lviv National Medical University, Ukraine

MD, PhD, Assistant of the Department of Propaedeutic Pediatrics and Medical Genetics


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How to Cite

Lychkovska OL, Kvit DI, Kulachkovska IY, Sadova ОM, Zhyvko LY, Dats-Opoka МI, Kosmynina NS. Post-COVID syndrome in children: whether a change in lymphocyte count is a risk factor for its development?. Zaporozhye medical journal [Internet]. 2022Dec.20 [cited 2024Feb.24];24(6):695-700. Available from:



Original research