[Epidemiological characteristics of reinfection of 2019-nCoV and influencing factors in Ningbo].

Objective: To analyze the epidemiological characteristics of reinfection of 2019-nCoV and influencing factors, and provide evidence for effective prevention and control of COVID-19 epidemic. Methods: The incidence data of COVID-19 in Ningbo from January 1, 2020 to November 30, 2022 were collected from the infectious disease surveillance system of Chinese information system for disease control and prevention. The incidence of reinfection of 2019-nCoV was investigated by using questionnaire. logistic regression analysis was used to analyze the influences of gender, age, time interval from the first infection, history of underlying disease, 2019-nCoV vaccination dose and disease severity on the reinfection. Results: A total of 897 previous 2019-nCoV infection cases were investigated, of which 115 experienced the reinfection of 2019-nCoV, the reinfection rate was 12.82%. The interval between the two infections M(Q1, Q3) was 1 052 (504, 1 056) days. Univariate analysis showed that age, 2019-nCoV vaccination dose, history of underlying disease, type of 2019-nCoV variant causing the first infection, time interval from the first infection and severity of the first infection were associated with the reinfection rate (all P<0.05). Multivariate logistic regression analysis showed that the risk for reinfection in age group 30- years was higher than that in age group ≥60 years (OR=2.10, 95%CI: 1.11-3.97). No reinfection occurred in those with time interval from the first infection of <6 months, and the risk for reinfection was higher in those with the time interval of ≥12 months than in those with the time interval of 6- months (OR=6.68, 95%CI: 3.46-12.90). The risk for reinfection was higher in the common or mild cases than in the asymptomatic cases (OR=2.64, 95%CI: 1.18-5.88; OR=2.79, 95%CI: 1.27-6.11). Conclusion: The time interval from the first infection was an important influencing factor for the reinfection of 2019-nCoV, and the probability of the reinfection within 6 months was low.

[Epidemiological characteristics of a local cluster epidemic caused by 2019-nCoV Delta variant in Ningbo, 2021].

Objective: To understand the epidemiological characteristics of a local clustered epidemic caused by 2019-nCoV Delta variant in Ningbo and provide reference for the improvement of COVID-19 epidemic prevention and control. Methods: Case finding was conducted based on case definitions, and field epidemiological investigation of COVID-19 cases was carried out. In which Nasal and oropharyngeal swabs of the cases were collected for pathogen testing, and the results were analyzed with descriptive epidemiological methods. Results: A total of 74 COVID-19 cases were reported in this epidemic, and the cases were mainly mild ones, accounting for 87.84% (65/74), and there were no severe or critical cases. The epidemic curve showed a human-to-human transmission mode, indicating that a transmission for at least six generations had occurred. The age of the COVID-19 patients ranged from 2 years to 80 years, and 27.03% (20/74) of the cases were older than 60 years. The cases were mainly workers (55.41%, 41/74) and housework/the unemployed (27.03%, 20/74). The COVID-19 epidemic was limited, and no further spread to other areas occurred. The transmission chain among the cases was clear, and the gene sequencing results confirmed that the current epidemic was caused by 2019-nCoV Delta variant, which was highly homologous to the strains from other province. Conclusion: The local COVID-19 epidemic in Ningbo was caused by imported cases of COVID-19 from other province, and local community spread occurred through daily contacts between cases and contacts.

[Analysis on infection risk in secondary close contacts of COVID-19 patients].

Objective: To study the infection rate of secondary close contacts of COVID-19 patients, and assess the infection risk in the contacts. Methods: COVID-19 patients' close contacts (with a clear exposure time to index case) with negative nucleic acid test results and secondary close contacts were surveyed in continuous isolation and medical observation in this prospective study. The dynamic nucleic acid test results of the close contacts and secondary contacts of COVID-19 patients were collected to assess their risk of infection. Results: A total of 4 533 close contacts were surveyed, in whom 14 were confirmed as COVID-19 patients with overall secondary attack rate of 0.31%, and 4 201 secondary contacts were tracked, in whom no subsequent infections occurred. Conclusion: Close contacts of COVID-19 patients entered in centralized isolation for medical observation with negative nucleic acid tese results,the secondary close contacts of COVID-19 patients have no risk of infection.

[Transmission chains of local epidemic of COVID-19 caused by 2019-nCoV Delta variant in Zhenhai district, Ningbo].

Objective: To investigate the local epidemic of COVID-19 caused by 2019-nCoV Delta variant in Zhenhai district of Ningbo, identify the transmission chain and provide reference for the prevention and control of COVID-19 epidemic. Methods: The incidence data of COVID-19 in Zhenhai from 6 to 18 December, 2021 were collected in field investigation. Field epidemiological investigation was conducted to understand the epidemiological characteristics of COVID-19 cases and analyze the transmission chains. Results: The first case might be infected with 2019-nCoV through direct or indirect exposure when passing through a medium-risk area, then a family cluster was caused, and the epidemic spread through close contacts of family members with others such as work, daily life, and moxibustion. The epidemic lasted for 14 days, and 74 confirmed COVID-19 cases were reported. The median incubation period was 4.0(3.0,5.8)d. All the cases were in a chain of transmission for more than 6 generations, and the intergenerational interval was 3.5(2.0,5.3)d. The gene sequencing result indicated that the pathogen was Delta AY.4 variant of 2019-nCoV. Both the epidemiological investigation and the gene sequencing results supported that the local COVID-19 epidemic in Zhenhai was associated with the COVID-19 epidemic in Shanghai. Conclusions: The transmission chain of this epidemic was clear. Delta AY.4 variant has obvious characteristic to cause case clusters in families, places with poor ventilation, and residential communities. It is suggested to strengthen the health management in key areas and key populations, and increase the frequency of nucleic acid testing.

[Analysis on infectivity of COVID-19 patients before and after last negative nucleic acid test].

Objective: To investigate the infection rate in close contacts of COVID-19 patients before and after the last negative nucleic acid test, evaluate the effect of dynamic nucleic acid test in determining the infectivity of COVID-19 patients. Methods: Dynamic nucleic acid test results of COVID-19 cases were collected in a retrospective cohort study. COVID-19 cases with negative nucleic acid test results before their first positive nucleic acid tests were selected as study subjects. Close contacts of the index cases and the secondary close contacts were kept isolation for medical observation to assess their risk of infection. Results: This study included 89 confirmed cases from two local COVID-19 epidemics in Ningbo. A total of 5 609 close contacts were surveyed, the overall infection rate was 0.20%. No close contacts of the COVID-19 cases before the last negative nucleic acid test were infected, and the infection rate in the close contacts of the COVID-19 cases after the last negative nucleic acid test was 1.33%, all of these close contacts lived together with the index cases. No secondary close contacts were infected. Conclusion: COVID-19 patient becomes infectious after the last nucleic acid is negative, and has no infectivity before the last nucleic acid negative.

Sensitivity of spiral computed tomography scanning for detecting intraocular foreign bodies.

OBJECTIVE: The purpose of this study is to determine whether 3-mm computed tomography (CT) cuts are equivalent to 1-mm CT cuts for detecting small intraocular foreign bodies (IOFBs). DESIGN: Experimental instrument validation study. PARTICIPANTS: Seventy-two porcine eyes were divided into three groups. Each group had 0.5 ml of human blood injected into the vitreous cavity and were surgically implanted with IOFBs. INTERVENTION: Each eye was surgically implanted with 0.5-mm metallic, 0.5-mm glass, or 0.5-mm stone IOFBs. Two additional eyes were left without IOFBs to serve as negative controls. MAIN OUTCOME MEASURES: Axial CT images of both 3-mm and 1-mm thickness were obtained and analyzed in masked fashion by two separate neuroradiologists. RESULTS: The sensitivity for detecting 0.5-mm metallic, 0.5-mm glass, and 0.5-mm stone IOFBs with 3-mm CT images was 100%. The sensitivity for detecting 0.5-mm metallic, 0.5-mm glass, and 0.5-mm stone IOFBs with 1-mm CT images was also 100% (confidence interval, 95%; range, 0.88-1.00). Two negative control eyes without IOFBs were also correctly evaluated by the neuroradiologists. CONCLUSIONS: With modern spiral CT scanning, 3-mm cuts are as sensitive as 1-mm cuts for detecting small metallic, glass, and stone IOFBs.

Refractive surgery in the new millennium.

As we stand at the threshold of a new millennium, perhaps nowhere else in the field of ophthalmology is there such a feeling of excitement, enthusiasm, and anticipation as in the subspecialty of refractive surgery. What was once considered an experimental hobby, dabbled in by a few rogue physicians, has now gained a level of respect among patients and ophthalmologists that has surprised even its most vocal critics.

Nitration and hydroxylation of aromatic amino acid and guanine by the air pollutant peroxyacetyl nitrate.

Peroxyacetyl nitrate (PAN) is a common gaseous photochemical compound in polluted air and cigarette smog. The toxicity of PAN has been found to depend on three pathways: (1) its oxidizing property that mimics peroxide or peroxynitrite; (2) its nitrating and hydroxylating properties similar to peroxynitrite; and (3) its acetylating property like acetic anhydride. The present investigations were intended to focus on the reactions of PAN with aromatic amino acids and guanine. When PAN interacted with tyrosine and guanine the major products were 3-nitrotyrosine, 3, 5-dinitrotyrosine, 8-hydroxyguanine and 8-nitroguanine. These compounds have been used as indicators for the presence of peroxynitrite in previous studies. When PAN interacted with phenylalanine, the products were 3-nitrotyrosine, 4-nitrophenylalanine, p-tyrosine, o-tyrosine and m-tyrosine. 5-Hydroxytryptophan is produced from the reaction of PAN with tryptophan. Furthermore, the formation of nitrated tyrosines was also found in the PAN-treated HL-60 cells. A high yield of dityrosine was formed when PAN and peroxynitrite were reacted with tyrosine, probably through free radical oxidation. We also found that peroxynitrite and PAN are similar in their oxidizing activity. From these findings, we suggest that peroxynitrite may be considered as the reactive intermediate of PAN.

Evaluation of giant-cell deposits on foldable intraocular lenses after combined cataract and glaucoma surgery.

PURPOSE: To compare the incidence of inflammatory giant-cell deposits (IGCDs) on various foldable intraocular lenses (IOLs) after combined cataract and glaucoma surgery. SETTING: The Phillips Eye Institute, Minneapolis, Minnesota, USA. METHODS: In this prospective randomized clinical trial, 128 patients were randomized to receive a single-piece, first-generation silicone lens (n = 36); a 3-piece acrylic lens (n = 40); or 3-piece, second-generation silicone lens (n = 52). All patients had combined phacoemulsification and trabeculectomy with mitomycin-C by 1 surgeon using a standardized technique. Dilated biomicroscopy was used to identify and quantitate IGCDs on the surface of the IOLs using a 6-point grading scale. RESULTS: Inflammatory giant-cell deposits were identified on 21 of 128 IOLs. Lens design was the most significant risk factor for deposit formation (P =.004). Inflammatory giant-cell deposits were most common in the first-generation silicone plate lens group (33%), less common in the acrylic lens group (15%), and least common in the 3-piece, second-generation silicone group (5.8%). Density of the deposits was significantly greater on the plate lens than the acrylic or the 3-piece silicone lenses (P <.0001). Although IOL design was the most significant risk factor for IGCD formation, other significant risk factors included intraoperative pupil stretch (P =.02) and preoperative miotic use (P =.04). CONCLUSION: Inflammatory giant-cell deposit formation was significantly greater on first-generation silicone plate IOLs than on acrylic or second-generation silicone IOLs. The deposits were somewhat more common on acrylic IOLs than on second-generation silicone IOLs. However, this difference was not clinically or statistically significant.

Six-month results of hyperopic and astigmatic LASIK in eyes with primary and secondary hyperopia.

PURPOSE: To assess the safety and efficacy of laser in situ keratomileusis (LASIK) for hyperopia and hyperopic astigmatism and develop a LASIK nomogram for primary hyperopia or hyperopia secondary to myopic refractive surgery using the VISX STAR S2. METHODS: Prospective evaluation of LASIK in 46 primary eyes and 29 secondary eyes with fogged manifest sphere from +0.5 diopters (D) to +6.0 D and cylinder from 0 to +5.0 D. RESULTS: Mean manifest spherical equivalent (SE) in patients with primary hyperopia was +2.50 D +/- 0.93 preoperatively and +0.70 D +/- 1.19 at 6 months. At 6 months, 79% of primary hyperopes had uncorrected visual acuity (UCVA) of 20/40 or better; 63% were within +/- 1 D of emmetropia. One primary hyperope lost 2 lines of best spectacle-corrected vision (BCVA) at 1 month. Complications included transient epithelial defect (6.5%), epithelial cells in the interface (4.3%), diffuse lamellar keratitis (4.3%), haze (2.2%), and mild irregular astigmatism (2.2%). In those with secondary hyperopia, mean manifest SE was +1.70 D +/- 0.82 preoperatively and -0.27 D +/- 0.95 at 6 months. At 6 months, 83% of secondary hyperopes had UCVA of 20/40 or better; 74% were within +/- 1 D of emmetropia. No secondary hyperope lost > or = 2 lines of BCVA. Complications included intraoperative bleeding (3.4%), intraoperative epithelial defect (3.4%), transient interface debris (3.4%), significant dry eye (3.4%), blood in interface (3.4%), irregular astigmatism (6.9%), slight decentration (6.9%), trace haze (6.9%), mild epithelial ingrowth not requiring removal (3.4%), or corneal irregularity (3.4%). CONCLUSION: These early data suggest that LASIK for hyperopia from +0.5 to +6 D and astigmatism from 0 to +5 D using the VISX STAR S2 benefits from a nomogram adjusted for preoperative refraction, age, and prior refractive surgery and is safe and effective. Patients with secondary hyperopia achieved more correction than those with primary hyperopia, although the accuracy and predictability of LASIK in both groups has improved with the nomogram adjustments.

Laser In Situ keratomileusis (LASIK) for the treatment of low moderate, and high myopia.

PURPOSE: To evaluate the efficacy, safety and predictability of LASIK in the treatment of low, moderate and high myopia. METHODS: A perspective study of LASIK for low myopia of -0.75 to -6.00 with less than +1 D of astigmatism and for moderate and high myopia of -6.12 to -20 D with astigmatism up to +4.50 D was performed at our institution from March through November, 1996. The Chiron automated corneal shaper was used for the initial flap, and either the Summit or VISX laser was used for the refractive ablation. Preoperative refraction, uncorrected and corrected visual acuity were compared to postoperative refraction, uncorrected and corrected visual acuity. One day and 1 month results were available on all patients. RESULTS: In the low myopia group 101 eyes underwent LASIK with a mean preoperative spherical equivalent of -4.16 +/- 1.41 D (-0.75 D to -6.00 D). Mean preoperative astigmatism was +0.4 +/- 1.29 D (0 to 0.75 D). At 1 day, 48% were 20/25 or better and 80% were 20/40 or better. The day 1 mean spherical equivalent was +0.4 +/- 0.75 D with 86% between +/- 1.00 D of emmetropia. At 1 month, 50% were 20/25 or better and 90% were 20/40 or better. The 1 month mean spherical equivalent was -0.26 +/- 0.65 D with 89% between +/- 1.00 D of emmetropia. In the high myopia group 198 eyes underwent LASIK with a preoperative mean spherical equivalent of -8.34 +/- 2.15 D)-6 to -20D) and a mean preoperative astigmatism of +1.18 +/- 0.88 D (0 to +4.5 D). At 1 day postoperatively, 17% were 20/25 or better, and 61% were 20/40 or better. The mean day one spherical equivalent was -0.26 +/- 1.56 D with 58% between +/- 1.00 D of emmetropia. At 1 month, 35% were 20/25 or better and 71% were 20/40 or better. The 1 month mean spherical equivalent was -0.28 +/- 1.18 with 63% within +/- 1.00 D of emmetropia. CONCLUSION: Early results of using LASIK to treat low, moderate and high degrees of myopia with and without astigmatism appear promising, although longer follow-up and nomogram refinement are needed.

Multifactorial etiology and multifaceted prevention strategy of hepatocellular carcinoma.

In many Asian and African countries, hepatitis B virus (HBV) has been identified as a major causative agent of hepatocellular carcinoma (HCC). In these endemic areas, HBV infection also occurs early in life. An internationally collaborative study on universal immunization of newborns against HBV to prevent HCC was initiated in September 1983 and expanded later in the rural Qidong County of China, a prevalent area of both HBV infection and HCC. The 5-year follow-up data of the pilot phase of this controlled study have shown encouraging results. Over 98% of the newborns in local communities were vaccinated and over 97% of the vaccinees are being followed. The vaccination group with boosted 5-micrograms regimen showed significantly reduced HBsAg positive rate at 5 years, 2.5 vs. 12.5% of the nonvaccinated age-matched control. The anti-HBs level was also enhanced. The main study starting from the beginning of 1985 has been progressing according to schedule. Striking male preponderance and peak age shift to younger age of HCC in the high incidence area strongly points to the action of cofactors that may further increase the risk. Male preponderance was not observed in the animal models of HCC induced by hepadnaviruses. These phenomena were associated with increased exposure to aflatoxins as measured by urinary excretion of AFM1, as well as with a high prevalence of tobacco smoking and alcohol consumption among the Chinese males. The clarification of the etiological role of cofactors has important implications in the possible prevention of HCC among HBV carriers.

A pilot study on universal immunization of newborn infants in an area of hepatitis B virus and primary hepatocellular carcinoma prevalence with a low dose of hepatitis B vaccine.

Hepatitis B virus (HBV) had been considered as the main causative factor of primary hepatocellular carcinoma and universal immunization of newborns was recommended as the major approach to control hepatitis and hepatoma in areas of prevalence. As the initial phase of the first vaccination program for such a purpose, a pilot study was done from September 1983 to May 1984 in a high incidence rural area of China. In an area of 214,343 inhabitants, 1,703 newborns (99% of all births) were vaccinated. Ninety-seven percent of all vaccinees were followed up at 1 year. The vaccine used was Hep-B Vax, given intramuscularly at 0, 1, and 6 months after birth. Four immunization regimes were used: 5-micrograms or 2.5-micrograms doses with or without hepatitis B immune globulin (HBIG) added in the case of carriers children. These groups were defined by drawing lots at community level. A matched control was selected on a voluntary basis. Each group consisted of 400 infants. Vaccination was proven to be very safe and well accepted by the public. The prevalence of HBV infection in the area was further demonstrated by the high HBsAg-positive rate measured: 14.2% of the 1,180 mothers (3.9% were also e-antigen positive), 7.6% and 10.1% of the unvaccinated children at 6.5 months and 1 year of age, respectively. It was shown that vaccination with a 5-micrograms or 2.5-micrograms dose significantly lowered the HBsAg positives to a level close to 1.5% versus 10% in the control group at 1 year. An 85% protection was thus achieved. A 5-micrograms dose plus HBIG did not show additional benefit. A 2.5-micrograms dose plus HBIG gave less protection, and anti-HB levels were also significantly lower than in other groups. Among the 12 failures found in the 5-micrograms and 2.5-micrograms groups, 11 were born to HBsAg-positive mothers, nine of whom also had e-antigen. Available data showed that 29% of children born by e-antigen-positive and 2.7% of children born by e-antigen-negative carriers had the risk of becoming carriers during the first year of life following vaccination. The present study demonstrated the feasibility and rationale of conducting universal immunization of newborns in endemic rural area for controlling hepatitis and hepatoma. The significance of the possible use of the vaccination at lower dose had also been stressed.

Measurement of individual aflatoxin exposure among people having different risk to primary hepatocellular carcinoma.

The establishment of the carcinogenic role of aflatoxins has been impeded by the lack of suitable tests to measure individual exposure for long-term studies. It was shown that the use of immuno-concentration followed by high pressure liquid chromatography (HPLC) or immunoassay can regularly detect aflatoxins down to pg/ml in fluids including urine. Aflatoxin M1 (AFM1) in free form was identified as the major metabolite in urine suitable for use as an approximate dosimetric indicator of recent exposure to aflatoxin B1 (AFB1). A panel of monoclonal antibodies of IgG class were developed in the murine system against AFB1 and/or AFM1. Their affinity constants are at the level of 10(8)-10(9) L/mol, and they are suitable for use in either effective immuno-concentration or in high sensitivity immunoassays. It was shown in a high risk area of liver cancer (Qidong of China) that 10% or more of the local inhabitants had a urinary output of AFM1 one or two orders of magnitude higher than that of Beijing people, especially during the wet seasons. The ingestion of AFB1 among these local people was estimated to exceed 1 mg/year. The major source came from contaminated corn and rice, but local alcoholic beverages also contributed. The increased excretion of AFM1 was more pronounced in patients with chronic active hepatitis. This observation of very low AFM1 content in urine of a significant percentage of local people implies their food storage practices may offer a feasible method for such prevention. The value and possible problems in conducting long-term studies on primary prevention are discussed.