[Analysis of clinical characteristics of 362 vaccinated or unvaccinated patients infected by novel coronavirus Omicron variant].

OBJECTIVE

To analyze the epidemiological and clinical characteristics of patients infected by novel coronavirus Omicron variant, and also to analyze whether vaccination against novel coronavirus has an impact on the severity and prognosis of Omicron patients.

METHODS

A prospective, single-center observational study was conducted to collect data of consecutive patients with Omicron variant infection admitted to the designated hospital for coronavirus disease 2019 (COVID-19) charged by Tianjin COVID-19 rescue medical team of Tianjin Third Central Hospital, from January 8 to February 2, 2022. The clinical characteristics of the patients were analyzed, and the influence of whether the patients were inoculated with booster vaccination on the condition and outcome was analyzed. Data were collected including epidemiological, clinical features, laboratory and imaging examination, treatment measures and clinical outcomes, and difference between groups was analyzed.

RESULTS

A total of 362 patients were included, including 136 cases (37.57%) in the booster group, 190 cases (52.49%) in the routine vaccination group, and 36 cases (9.94%) in the unvaccinated group. There was a trend of concentrated distribution of patients, of which 171 cases (47.24%) patients showed family clustering, involving 69 families. Seventy-four cases (20.44%) of the 362 patients had one or more underlying diseases, mainly hypertension (64 cases, 17.68%), diabetes mellitus (23 cases, 6.35%), and coronary heart disease (18 cases, 4.97%); 215 patients (59.39%) had one or more discomfort symptoms, mainly cough (158 cases, 43.65%), pharyngeal discomfort (154 cases, 42.54%) and fever (136 cases, 37.57%). The diagnostic typing was mild type in 194 cases (53.59%), moderate type in 165 cases (45.58%) and severe type in 3 cases (0.83%). The patients had elevated immunoglobulin G (IgG) antibody titers to the novel coronavirus on admission [23.17 (3.08, 60.77)]. Patients were medically isolated and the main treatment measures included traditional Chinese medicine identification (Chinese medicine or tonics) in 265 cases (73.20%), prone treatment in 188 cases (51.93%), anticoagulation with low-molecular heparin in 106 cases (29.28%), immunomodulatory therapy with thymofacine in 21 cases (5.80%), antimicrobial drugs in 20 cases (5.52%), transnasal high-flow oxygen therapy in 12 cases (3.31%), glucocorticoids in 5 cases (1.38%), non-invasive mechanical ventilation in 1 case (0.28%), and invasive mechanical ventilation in 1 case (0.28%). A total of 362 patients were discharged with no deaths, of which 12 patients (3.31%) were admitted to the intensive care unit (ICU). The median duration of illness was 13 (10, 15) days, the median length of hospitalization was 13 (11, 15) days, and the median time to nucleic acid conversion was 13 (10, 15) days. Compared with the unvaccinated group, the IgG antibody titers of patients in the booster and routine vaccination groups [41.49 (20.32, 81.38), 19.94 (2.33, 49.25) vs. 0.16 (0.07, 1.94)] and the proportion of mild patients [66.91% (91/136), 48.94% (93/190) vs. 27.28% (10/36)] were higher, which were also higher in the booster vaccination group than in the conventional vaccination group (all P < 0.05). Compared to the conventional and booster vaccination groups, the unvaccinated group had a higher proportion of severe patients [5.56% (2/36) vs. 0.53% (1/190), 0 (1/136)], longer time to nucleic acid conversion [days: 15 (11, 16) vs.12 (10, 15), 13 (11, 15)], and longer disease duration [days: 15 (11, 16) vs. 12 (10, 15), 13 (11, 15)], and a higher percentage of ICU admissions [16.67% (6/36) vs. 2.63% (5/190), 0.74% (1/136)], with statistically significant differences among the three groups (all P < 0.05).

CONCLUSIONS

Omicron variant is extremely infectious with aggregated onset, but its clinical symptoms are mild. The vaccine, especially the booster vaccination, remains effective in preventing severe-stage progression and improving prognosis in patients with Omicron variant infection.