Imbalance of Peripheral Temperature, Sympathovagal, and Cytokine Profile in Long COVID

A persistent state of inflammation has been reported during the COVID-19 pandemic. This study aimed to assess short-term heart rate variability (HRV), peripheral body temperature, and serum cytokine levels in patients with long COVID. We evaluated 202 patients with long COVID symptoms categorized them according to the duration of their COVID symptoms (=120 days, n = 81; >120 days, n = 121), in addition to 95 healthy individuals selected as controls. All HRV variables differed significantly between the control group and patients with long COVID in the =120 days group (p < 0.05), and participants in the long COVID =120 days group had higher temperatures than those in the long COVID >120 days group in all regions analysed (p < 0.05). Cytokine analysis showed higher levels of interleukin 17 (IL-17) and interleukin 2 (IL-2), and lower levels of interleukin 4 (IL-4) (p < 0.05). Our results suggest a reduction in parasympathetic activation during long COVID and an increase in body temperature due to possible endothelial damage caused by the maintenance of elevated levels of inflammatory mediators. Furthermore, high serum levels of IL-17 and IL-2 and low levels of IL-4 appear to constitute a long-term profile of COVID-19 cytokines, and these markers are potential targets for long COVID-treatment and prevention strategies.

Automated summary

This study assessed short-term heart rate variability, peripheral body temperature, and serum cytokine levels in patients with long COVID. The results showed significant differences in HRV variables between the control group and patients with long COVID symptoms lasting ≤120 days, and patients in the shorter duration group had higher temperatures. Cytokine analysis revealed elevated levels of IL-17 and IL-2, and decreased levels of IL-4. These findings suggest autonomic dysfunction and elevated body temperature in long COVID patients, possibly due to endothelial damage caused by persistent high levels of inflammatory mediators. Additionally, high levels of IL-17 and IL-2 and low levels of IL-4 may serve as markers for long-term COVID-19 cytokine profiles and potential targets for long COVID treatment and prevention strategies.