Analysis on infectivity of COVID-19 patients before and after last negative nucleic acid test
10.3760/cma.j.cn112338-20220301-00164
- VernacularTitle:新型冠状病毒感染者末次核酸阴性前后的传染性分析
- Author:
Yanru CHU
1
;
Yanwu ZHANG
;
Song LEI
;
Yi CHEN
;
Dongliang ZHANG
;
Xiaomin GU
;
Xuying LAO
;
Haibo WANG
;
Xiandong SHEN
;
Qunxiong HU
;
Bo YI
;
Enfu CHEN
;
Guozhang XU
Author Information
1. 宁波市疾病预防控制中心，宁波 315010
- Keywords:
2019-nCoV;
Nucleic acid testing;
Infectivity
- From:
Chinese Journal of Epidemiology
2022;43(6):841-845
- CountryChina
- Language:Chinese
-
Abstract:
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.
