[Retrospective observation and analysis of autoimmune-related indicators in 317 patients with acute Omicron variant infection].

OBJECTIVE

To compare the changes of clinical characteristics and immune-related indicators of patients with mild and moderate acute Omicron variant infection, and to evaluate the protective effect of coronavirus disease 2019 (COVID-19) vaccination.

METHODS

The study retrospectively analyzed the clinical characteristics of 317 adult patients diagnosed with COVID-19 Omicron variant (B1.1.529) infection admitted to Tianjin First Central Hospital (Shuixi District) from January 22, 2022 to February 24, 2022. Demographic characteristics, vaccination status, underlying diseases, epidemiological characteristics, baseline data, and relevant laboratory test results on admission were collected, and the differences in clinical characteristics, especially the changes in immune-related indicators, between mild and moderate patients were compared and analyzed.

RESULTS

Among the 317 adult patients with acute Omicron variant infection, the proportion of elderly, hypertension, diabetes, and cardiovascular or cerebrovascular diseases were significantly higher in moderate group (203 cases) than those of mild group (114 cases) [age ≥ 60 years old: 27.58% (56/203) vs. 9.65% (11/114), hypertension: 31.03% (63/203) vs. 19.30% (22/114), diabetes: 15.76% (32/203) vs. 7.89% (9/114), cardiovascular and cerebrovascular diseases: 11.33% (23/203) vs 0.88% (1/114), all P < 0.05]. The route of transmission was mainly through gatherings and the first symptoms were fever, dry cough, fatigue, sore throat, nasal congestion, runny nose and other flu symptoms; 19.30% (22/114) and 24.63% (50/203) of patients in mild and moderate groups were positive for the new coronavirus nucleic acid test, respectively, but the difference was not significant difference (P > 0.05). Inflammatory indicators in most mild and moderate patients were within normal range, such as white blood cell count (WBC), neutrophil ratio (NEU%), lymphocyte count (LYM), C-reactive protein (CRP), procalcitonin (PCT), and interleukin-6 (IL-6), etc., suggesting that the acute phase of Omicron variant infection had not yet caused severe inflammatory storm, which might be related to the weakening of pathogenicity after vaccination and virus mutation. The proportion of patients with IL-6 > 7 ng/L in the mild group was significantly lower than that in the normal group [1.75% (2/114) vs. 6.40% (13/203), P < 0.05], suggesting that elevated IL-6 might be an important factor in evaluating indicators of disease severity. There was no significant difference in lymphocyte subsets between the two groups, but there were 12.90% (12/93) and 11.04% (17/154) of the patients in two groups, respectively, decreased in the proportion of helper T cells, and 18.28% (17/93) and 14.28% (22/154) of the patients had elevated CD4/CD8 ratio, suggesting that patients with Omicron variant infection had autoimmune system dysfunction, which might be related to disease progression and the occurrence of long-term autoimmune disease.

CONCLUSIONS

Serum IL-6 level may be used as a predictor for evaluating the severity of disease in patients with Omicron variant infection; after vaccination, inflammatory indicators in patients with acute Omicron variant infection were significantly reduced, but the long-term effects still require long-term follow-up observation.