Comparison of clinical features of Omicron and Delta cases

ABSTRACT

Objective: To compare the clinical features of Omicron and Delta cases, so as to provide scientific basis for the prevention and treatment of COVID-19. Methods: The case-control study method was used to retrospectively analyze the clinical data of the Omicron cases admitted to the designated hospital for the treatment of COVID-19 in Xi'an from December 2021 to January 2022. and the Delta cases admitted during the same period were used as the control group. The demographic data, epidemiological history, vaccination status, clinical characteristics, laboratory tests, nucleic acid and antibody levels, and outcomes of patients in the two groups were collected and compared. Results: A total of 21 patients were included in the study, 5 were Omicron patients and 16 were Delta cases. The mean age of the patients in the two groups were (38.20±15.07) and (37.69±10.39) years, respectively.The time interval between the last vaccination and the diagnosis was (145.40±77.92) days and (159.00±99.74) days, respectively. For the initial symptoms, the patients with Omicron were mainly characterized by throat discomfort (3, 60%), cough and sputum (2, 40%), and the patients with Delta were mainly characterized by throat discomfort (5, 31.25%), fatigue (5, 31.25%), cough and sputum (4, 25%). On admission, laboratory tests showed that 60% of Omicron patients had low lymphocytes and elevated erythrocyte sedimentation rate, and 50% of patients in the delta group had elevated hemoglobin. The Ct values of ORFlab gene, N gene and E gene with Omicron were lower than those with Delta. And the difference of E gene between the two groups was statistically significant (t=-2.711, P=0.024). IgG antibody levels increased in both groups.The time for nucleic acid to turn negative with Omicron was (28.20±5.89) days, and it was (18.50±7.73) days with Delta, and the difference between the groups was statistically significant (t=2.565, P=0.019). The length of hospitalization with Omicron was (30.60±4.88) days, and that with Delta was (22.13±7.81) days, and the difference was statistically significant (t=2.270, P =0.035). Conclusions: The initial symptoms of Omicron patients are mainly throat discomfort, cough and sputum. The clinical manifestations are generally mild. The nucleic acid test Ct value is lower. The time for nucleic acid to turn negative and the time for hospitalization are longer, and the potential infectiousness is stronger. Those eligible for vaccination should complete the full course of vaccination and booster vaccination as soon as possible. At the same time, the management of "early detection, early reporting, early isolation, and early treatment" should be implemented.