key: cord-0863026-f6nz4glj
authors: Chen, Heng; Mao, Yi; Duan, Zhenhua; Wang, Liang; Cheng, Yue; Dai, Yingxue; Luo, Haixia; Xie, Wenjun; Fan, Shuangfeng; Zhou, Yuzhen; Xu, Jingpei; Feng, Lan; Hu, Liwen; Liu, Zhu; Liang, Xian; Jiang, Liangshuang; Tuo, Xiaoli
title: Three Cases of COVID-19 Variant Delta With and Without Vaccination — Chengdu City, Sichuan Province, April–May, 2021
date: 2021-06-18
journal: China CDC Wkly
DOI: 10.46234/ccdcw2021.137
sha: 15bf42837956928dc7dd2124ed7b0b51f5d1c780
doc_id: 863026
cord_uid: f6nz4glj

nan

P681R, and D950N listed in the sub-lineage of B.1.617.2 (variant Delta) that was assigned by a web analytical tool as B.1.617.2 (3) , which had been circulating in India since December 2020 and was designated as one of the variants of concern (VOCs) by the World Health Organization (WHO) (4). The phylogenetic tree by CLC Main Workbench 11.0 (QIAGEN, Dusseldorf, Germany) was shown in Figure 1 .

Cases A, B, and C of COVID-19 were transferred to the Public Health Clinical Center of Chengdu for treatment in isolation on April 26, May 3, and May 10, 2021, separately (the main clinical events are shown in Figure 2 ). Soon after the admission, they all were found to have an increase in lung lesions according to chest computed tomography (CT) abnormalities. During the isolation treatment period, 3 differences were found between the vaccinated and unvaccinated patients: 1) The IgG\IgM	otal antibodies tests were positive for Case A on the 4th day, positive for Case C on the 1st day with high titer, and negative for Case B even on the 7th day (negative for IgM during the entirety of hospitalization and positive for IgG and total antibodies on the 13th day with low titer), which suggested that the time from diagnosis to antibody positivity was shorter in vaccinated cases than in unvaccinated cases [ Figure 3 shows the results of IgM and total antibodies results with chemiluminescence immunoassay (CLIA)]. 2) The cycle threshold (Ct) value of fluorescent PCR seems lower in samples from unvaccinated patients than those from the vaccinated ones [ Figure 4 shows the results of Ct values of the open reading frame (ORF)]. There is a similar finding that a significant increase in Ct in vaccinated individuals than matched unvaccinated control group infections (n=1,888) from days 12-37 after vaccination was reported (5).

3) The length of hospitalization was shorter for vaccinated patients than for unvaccinated one. Case A and Case C were discharged after 21 and 25 days in the hospital, respectively, and Case B was discharged on June 7 after 36 days.

The variant Delta strains were imported into China and exerted a great threat to the prevention and control of COVID-19. Further studies looking into the epidemiological impacts of the variants and the effects of the vaccine are urgently needed. As local outbreaks of COVID-19 are still reported in Anhui, Liaoning, and Guangdong, vaccination should be taken as the first strategy and promoted efficiently for the disease control for COVID-19.

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Severe acute respiratory syndrome coronavirus 2 isolate 1

A new coronavirus associated with human respiratory disease in China

Phylogenetic assignment of named global outbreak LINeages

WHO Weekly epidemiological update on COVID-19 -8