Latent period and incubation period with associated factors of COVID-19 caused by Omicron variant / 中华预防医学杂志

Objective: To estimate the latent period and incubation period of Omicron variant infections and analyze associated factors. Methods: From January 1 to June 30, 2022, 467 infections and 335 symptomatic infections in five local Omicron variant outbreaks in China were selected as the study subjects. The latent period and incubation period were estimated by using log-normal distribution and gamma distribution models, and the associated factors were analyzed by using the accelerated failure time model (AFT). Results: The median (Q1, Q3) age of 467 Omicron infections including 253 males (54.18%) was 26 (20, 39) years old. There were 132 asymptomatic infections (28.27%) and 335 (71.73%) symptomatic infections. The mean latent period of 467 Omicron infections was 2.65 (95%CI: 2.53-2.78) days, and 98% of infections were positive for nucleic acid test within 6.37 (95%CI: 5.86-6.82) days after infection. The mean incubation period of 335 symptomatic infections was 3.40 (95%CI: 3.25-3.57) days, and 97% of them developed clinical symptoms within 6.80 (95%CI: 6.34-7.22) days after infection. The results of the AFT model analysis showed that compared with the group aged 18-49 years old, the latent period [exp(β)=1.36 (95%CI: 1.16-1.60), P<0.001] and incubation period [exp(β)=1.24 (95%CI: 1.07-1.45), P=0.006] of infections aged 0-17 years old were prolonged. The latent period [exp(β)=1.38 (95%CI: 1.17-1.63), P<0.001] and the incubation period [exp(β)=1.26 (95%CI: 1.06-1.48), P=0.007] of infections aged 50 years old and above were also prolonged. Conclusion: The latent period and incubation period of most Omicron infections are within 7 days, and age may be a influencing factor of the latent period and incubation period.

Latent period and incubation period with associated factors of COVID-19 caused by Omicron variant / 中华预防医学杂志

Objective: To estimate the latent period and incubation period of Omicron variant infections and analyze associated factors. Methods: From January 1 to June 30, 2022, 467 infected persons and 335 confirmed cases in five local Omicron variant outbreaks in China were selected as the study subjects. The latent period and incubation period were estimated by using log-normal distribution and gamma distribution models, and the associated factors were analyzed by using the accelerated failure time model (AFT). Results: The median (Q1, Q3) age of 467 Omicron infections including 253 males (54.18%) was 26 (20, 39) years old. There were 132 asymptomatic infections (28.27%) and 335 (71.73%) symptomatic infections. The mean latent period of 467 Omicron infections was 2.65 (95%CI: 2.53-2.78) days, and 98% of infections were positive for nucleic acid detection within 6.37 (95%CI: 5.86-6.82) days after infection. The mean incubation period of 335 symptomatic infections was 3.40 (95%CI: 3.25-3.57) days, and 97% of them developed clinical symptoms within 6.80 (95%CI: 6.34-7.22) days after infection. The results of the AFT model analysis showed that compared with the group aged 18~49 years old, the latent period [exp(β)=1.36 (95%CI: 1.16-1.60), P<0.001] and incubation period [exp(β)=1.24 (95%CI: 1.07-1.45), P=0.006] of infections aged 0~17 year old were also prolonged. The latent period [exp(β)=1.38 (95%CI: 1.17-1.63), P<0.001] and the incubation period [exp(β)=1.26 (95%CI: 1.06-1.48), P=0.007] of infections aged 50 years old and above were also prolonged. Conclusion: The latent period and incubation period of most Omicron infections are within 7 days, and age may be the influencing factor of the latent period and incubation period.

Time distribution of positive nucleic acid detection in imported cases infected with SARS-CoV-2 in China / 中华流行病学杂志

Objective: To analyze the time distribution of the first positive nucleic acid detection in imported cases infected with SARS-CoV-2 reported nationwide in China and provide references for further improvement of the prevention and control of COVID-19 in international travelers. Methods: The data of imported cases infected with SARS-CoV-2 reported by provinces from 24 July 2020 and 23 July 2021 were collected for the analysis on the time distribution of the first positive nucleic acid detection after entering China. Results: A total of 7 199 imported cases infected with SARS-CoV-2 were reported in 28 provinces during 24 July 2020 to 23 July 2021. The median interval (Q1, Q3) from the entry to the first positive nucleic acid detection of SARS-CoV-2 was 1 (0, 5) day. The imported cases who had the first positive nucleic acid detections within 14 days and 14 days later after the entry accounted for 95.15% (6 850/7 199) and 4.85% (349/7 199) respectively. Among these cases, 3.65% (263/7 199), 0.88% (63/7 199) and 0.32% (23/7 199) had the first positive nucleic acid detections within 15-21 days, 22-28 days and 28 days later after the entry respectively. The proportion of asymptomatic infections were 47.24% (3 236/6 850) and 63.61% (222/349) among the cases who had the first positive nucleic acid detections within 14 days and 14 days later after the entry respectively. A total of 39.54% (138/349) of cases infected with SARS-CoV-2 with the first positive nucleic acid detections 14 days later after the entry had inter-provincial travel after the discharge of entry point isolation. Conclusions: About 5% of the imported cases infected with SARS-CoV-2 were first positive 14 days later after the entry. In order to effectively reduce the risk of domestic COVID-19 secondary outbreaks caused by imported cases, it is suggested to add a nucleic acid test on 8th -13th day after the entry.

Murine corneal stroma cells suppress bone marrow-derived dendritic cells maturation in vitro / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Prostaglandin E2 (PGE(2)) is a key modulator of dendritic cells (DCs) function, and cornea-derived transforming growth factor beta 2 (TGF-β(2)) promotes the generation of phenotypically and functionally immature DCs. Therefore, this study was carried out to investigate whether PGE(2) is involved in the suppressive effect on DCs maturation mediated by corneal stroma cells (CSCs) and whether PGE(2) and TGF-β(2) have additive effects in this immunosuppressive mechanism.</p><p><b>METHODS</b>Bone marrow-derived DCs (BM-DCs), splenic T cells and CSCs culture supernatant were obtained from mice via various protocols. After that, the level of PGE(2) in CSCs culture supernatant was analyzed by enzyme-linked immunosorbent assay. Then, immature BM-DCs pretreated by E-prostanoid 2 receptor antagonist AH6809 or dimethyl sulfoxide were induced to mature in the presence of lipopolysaccharide, with or without CSCs culture supernatant. In parallel experiments, neutralizing TGF-β(2) antibody or normal goat IgG was added into the supernatant. Next, the cellular surface markers for DCs maturation, including CD80, CD86, and major histocompatibility complex class II (MHCII), were analyzed by flow cytometry; the capability of stimulating the proliferation of T lymphocytes was evaluated by allogeneic mixed lymphocyte reactions and the function of endocytosis was assessed by fluorescein isothiocyanate-dextran uptake.</p><p><b>RESULTS</b>Higher concentration of PGE(2) was detected in CSCs culture supernatant than in the fresh medium. In addition, compared with control group, after treated with the supernatant in the mature stage, BM-DCs displayed lower expression of CD80, CD86 and MHC II, lower T cell stimulatory capacity and higher endocytosis function. However, after the application of AH6809, BM-DCs partially regained T cell stimulatory capacity and expression of CD86 and MHC II, but partially lost endocytic activity. Moreover, after the application of AH6809 and neutralizing TGF-β(2) antibody, the result of statistical analysis indicated that there was a statistical difference of interaction in the expression of MHC II and T cell stimulatory capacity.</p><p><b>CONCLUSIONS</b>PGE(2) contributes to the suppressive effect on BM-DCs maturation mediated by CSCs in vitro, and PGE(2) and TGF-β(2) have additive effects on the immunosuppression of BM-DCs.</p>

Thirty-two cases of blow-out fracture with orbital floor repaired by auto-cranial pedicle flap / 眼科

2cm~2.Conclusions The auto-cranial pedicle flap via endonasal repairing blow-out fractures of or- bital inferior wails is an effective technique.The results are good for improving eye movement especially for fracture ranged≤2cm~2. (Ophthalmol CHN,2007,16:388-390)