Lipid Peroxidation Processes in Convalescents after COVID-19: Their Diagnostic Significance and Correction under the Influence of Rehabilitation Treatment
Authors: Lemko Olha , Gabor Magdalyna , Vantiukh Nataliia , Reshetar Diana , Lukashchuk Svitlana 
Published: January 2025

Despite global response to the COVID-19 pandemic, humanity has not been able to completely elimination of the SARS-CoV-2 virus. And although the acute period of COVID-19 is currently relatively mild, there is still a risk of the post-COVID syndrome with persistent multisystem disorders development, which necessitates restorative treatment during the convalescence period.
The objective: to assess the severity of oxidative stress and the possible role of immune complex lesions in convalescents after COVID-19 in relation to the severity of the disease and the timing of examination after the acute period, as well as to analyze the dynamics of the detected changes under the influence of rehabilitation treatment.
Materials and methods. 91 convalescents after COVID-19 were examined. In patients aged 21 to 67 years, the manifestations of COVID pneumonia were diagnosed during the acute period. Among them, 46 patients had a mild course of COVID-19, 31 persons had a moderate course, and 14 patients had a severe course. Within 1–3 weeks after inpatient treatment 55 patients were admitted to a rehabilitation treatment course, and after 2–3 months – 36 persons. The comparison group included 25 convalescents after community-acquired bacterial pneumonia. As a control for laboratory indicators, 27 practically healthy individuals were examined.
During the examination the disorders in the lipid peroxidation (LPO) – antioxidant protection (AOP) system were studied, examining the level of LPO end products – Schiff bases (SB) and the AOP enzyme – catalase in the blood. To quantify the imbalance in the ROS-AOD system, the oxidative stress severity index (OSI) was calculated. The presence of endogenous intoxication was assessed by determining the average mass molecules (AMM) in the blood serum by spectrophotometric method. To assess the development of immune complex lesions, the level of circulating immune complexes (CIC) was determined.
The main component of the treatment was the use of haloaerosol therapy (dry aerosol media of rock salt with a given concentration and dispersion) – 18–20 sessions per course. In addition, rehabilitation treatment included a gentle regimen with regular therapeutic physical exercises, the necessary basic bronchodilator and anti-inflammatory therapy (according to indications).
Results. Before the treatment in the convalescents there were the signs of pronounced oxidative stress and endotoxemia, which was manifested by a significant increase in the level of BS in the control group and in patients after bacterial pneumonia. These changes were combined with a significant increase in MSM content by 1.3 times and CIC level by 2.1 times, which causes the development of tissue damage and post-covid syndrome. The detected changes did not significantly depend on the timing of the examination and were pronounced even with a mild course of COVID-19.
After the course of rehabilitation treatment all patients, regardless of the severity of the disease, had inhibition of lipoperoxidation, which was accompanied by an increase in catalase activity and was confirmed by a significant OSI decrease, a decrease in endotoxemia and CIC level. The positive dynamics of the studied indicators was somewhat more pronounced with a mild course of COVID-19, but by the end of the course of treatment, none of the indicators reached the control level. This fact confirms the pathogenetic significance of the studied processes in the development of post-covid syndrome and determines the need to improve rehabilitation treatment of convalescents after COVID-19.
Conclusions. After COVID-19 disease the convalescents have disturbances in the redox balance with the development of oxidative stress, manifestations of endogenous intoxication and immune complex reactions, which do not significantly depend on the severity of the acute period of the disease and persist for a long time, which may be the basis for the development of post-covid syndrome.
The rehabilitation therapy based on haloaerosol therapy leads to an improvement in clinical and functional indicators and a decrease in the manifestations of oxidative stress and endotoxemia, but does not provide full compensation for these changes, which determines the need to correct the rehabilitation complex with an emphasis on restoring oxidative homeostasis.