ABSTRACT
ObjectiveTo describe the epidemic characteristics of COVID-19 after policy adjustment from “Category B notifiable disease with category A management” to “Category B notifiable disease with category B management”， and to explore the protective effect of previous infection with SARS-CoV-2 on common symptoms of reinfection. MethodsHealthcare workers infected with SARS-CoV-2 in a grade A tertiary hospital in Shanghai were included in the study from December 4， 2022 to January 11， 2023. Data on demographic characteristics， clinical symptoms， medical history， and COVID-19 vaccination history were collected. We determined the epidemiological curve and characteristics， and then compared the difference in the severity of clinical symptoms between primary and reinfection subjects. ResultsA total of 2 704 cases were included in the study， of which 45 had reinfection， 605 （22.4%）were males， 608 （22.5%）were doctors， 1 275 （47.2%） were nurses， and 2 351 （86.9%） received ≥3 doses of COVID-19 vaccination. The average age of these healthcare workers was （34.9±9.1） years old. The number of cases with mild/moderate illness， asymptomatic infection， fever， headache， dry cough， expectoration， and chest tightness were 2 704 （100.0%）， 92 （3.4%）， 2 385 （88.2%）， 2 066 （76.4%）， 1 642 （60.7%）， 1 807 （66.8%）， and 439 （16.2%）， respectively. Reinfection was a protective factor for fever （OR=0.161， P<0.001）， headache （OR=0.320， P<0.001）， and peak body temperature （β=-0.446， P<0.001）. ConclusionFollowing the COVID-19 policy adjustment as a category B notifiable disease， healthcare workers at a grade A tertiary hospital in Shanghai predominantly experiences mild to moderate COVID-19 symptoms. Reinfection results in milder clinical manifestations， with a lower proportion of being asymptomatic.
ABSTRACT
Objective To explore the relationship between reduction of regional cerebral blood flow in the normal appearing white matter (NAWM) and the extent of age-related white matter lesions (WML).Methods We used Fazekas scale to divide all participants into four groups (normal,mild,moderate,severe) according to the extent of the lesions showed on MRI.Regional cerebral blood flow (rCBF) in the area of WML and NAWM was measured by xenon contrast CT examination.Results A total of 56 cases were selected.The average rCBF (ml · 100 g-1 · min-1) in the lesions (WML) around ventricle,in right centrum ovale and in left centrum ovale respectively was 20.33 ± 2.52,21.27 ± 1.02,21.03 ± 1.83 for mild; 16.33 ±2.03,15.55 ±1.71,15.91 ±0.98 for moderate; 14.05 ±2.63,14.46 ±2.17,14.23 ± 1.95 for severe.The average rCBF (ml · 100 g-1 · min-1) in the NAWM around ventricle,in right centrum ovale and in left centrum ovale respectively was 20.79 ± 2.78,22.26 ± 1.9,22.15 ± 2.4 for normal; 21.12 ± 2.95,22.17 ± 1.50,22.25 ± 2.13 for mild,18.02 ± 2.41,19.45 ± 1.94,19.62 ± 1.54for moderate; 16.38 ± 3.22,18.18 ± 2.84,16.74 ± 2.97 for severe.The decrease of rCBF in the severe and moderate lesion areas was more serious than that in the mild lesion areas and reached statistic significance (P ＜ 0.05) ; The decrease of rCBF in the severe and moderate lesion areas was more serious than that in the area of NAWM in the same grade and reached statistic significance (P ＜ 0.05).The decrease of rCBF in the area of NAWM around severe and moderate lesion areas was more serious compared with that around mild lesion areas or normal areas (P ＜ 0.05) ; But the difference of rCBF in the area of NAWM around mild lesion areas and normal areas did not show any statistic significance.Conclusions Chronic ischemia was found to be existed not only in the lesions (WML) but also in the area of NAWM around the lesions,and was related to the extent of the lesions.Chronic ischemia may play a key role in the mechanism of aged-related WML.