key: cord-294392-a8s66g96
authors: Zhang, Shuai; Guo, Mengfei; Wu, Feng; Xiong, Nian; Ma, Yanling; Wang, Zhihui; Duan, Limin; Chen, Lan; Ouyang, Haixia; Jin, Yang
title: Factors associated with asymptomatic infection in health-care workers with SARS-CoV-2 infection in Wuhan, China: a multi-center retrospective cohort study
date: 2020-09-07
journal: Clin Microbiol Infect
DOI: 10.1016/j.cmi.2020.08.038
sha: 
doc_id: 294392
cord_uid: a8s66g96

OBJECTIVES: We aim to describe the fraction of asymptomatic health-care workers (HCWs) in two designated hospitals for COVID-19 treatment in Wuhan and explore the factors associated with asymptomatic SARS-CoV-2 infection. METHODS: All HCWs in Wuhan Union Hospital and Wuhan Red Cross Hospital with either positive SARS-CoV-2 nucleic acid or antibody test before April 18, 2020 were included. Exposure, epidemiologic, demographic information were retrospectively collected by a structured questionnaire. Medical records were also reviewed for clinical characteristics and CT images in HCWs. RESULTS: As of April 18, 2020, a total of 424 HCWs were identified. Among them, 276 (65.1%) were symptomatic and 148 (34.9%) were asymptomatic. 55 (19.9%) families of the symptomatic HCWs and 16 (10.8%) families of the asymptomatic HCWs were infected with SARS-CoV-2. HCWs with infected family members tend to be symptomatic cases (Odds ratio [OR], 2.053 [95% confidence interval (CI), 1.130-3.730]; P=0.018). Multivariable logistic regression analysis exhibited that performing tracheal intubation or extubation (OR, 4.057 [95% CI, 1.183-13.909]; P=0.026) was associated with an increased likelihood of symptomatic SARS-CoV-2 infection, while consistent use of N95 respirators (OR, 0.369 [95% CI, 0.201-0.680]; P=0.001) and eye protection (OR, 0.217 [95% CI, 0.116-0.404]; P<0.001) were associated with an increased likelihood of asymptomatic SARS-CoV-2 infection. CONCLUSIONS: Asymptomatic SARS-CoV-2 infection in HCWs occupies a considerable proportion during the pandemic of COVID-19. Those who have performed tracheal intubation or extubation were most likely to develop related symptoms, while those taking aggressive measures including consistent use of N95 masks, and eye protection tended to be asymptomatic cases.

The ongoing outbreak of 2019 novel coronavirus disease (COVID-19) has been reported in Wuhan,

China and spread rapidly across the world. 1,2 Health-care workers (HCWs) have been at high risk for 

The RNA extraction, RT-PCR assay and antibodies test were done according to the previous study. 9 .

Total RNA was extracted from nasopharyngeal and/or oropharyngeal swab samples of HCWs within 2 79 hours using the respiratory sample RNA isolation kit (Xi'an Tianlong Science and Technology CO.,Ltd.

and Guangzhou HEAS BioTech Co., Ltd. ). RT-PCR assay was performed by using detection kit for 81 SARS-CoV-2 RNA (Wuhan Easydiagnosis Biomedicine Co., Ltd. and Daan Gene Co., Ltd. of Sun

Yat-sen University). The serum SARS-CoV-2 antibodies were detected using the diagnostic kit for IgM 83 / IgG antibody to SARS-CoV-2 (Zhuhai Livzon Diagnostics Inc.)

Isolation wards, fever outpatient clinics, emergency departments, ICU, medical laboratories, and hypertension, cardiovascular disease, diabetes, cerebrovascular disease, chronic obstructive pulmonary 90 disease (COPD), chronic kidney disease, chronic liver disease, rheumatic diseases and malignancy. 

hair cover and eye protection) were available for the next step. A previous study had shown younger 117 age was associated with asymptomatic SARS-CoV-2 infection. 8 Another study showed that age and 118 comorbidities were predictors for symptom development in the initially asymptomatic carriers at 119 admission. 12 Two studies showed that tracheal intubation procedure was related to increased risk of 120 transmission SARS-CoV-1 and SARS-CoV-2 to HCWs. 13,14 Face mask and eye protection especially 121 N95 respirators were most consistently with reduced COVID-19 infection among HCWs. 14,15 Face 122 mask was also reported to be associated with asymptomatic SARS-CoV-2 infection based on several 123 uncontrolled reports. 16 Therefore, we chose age, comorbidities, tracheal intubation or extubation, N95 124 respirators, eye protection as the five variables for our multivariable logistic regression model and were 125 adjusted by using an enter approach.

In the analysis, frequency of using PPE and frequency of hands hygiene practice were coded into 2 127 categories: used inconsistently (i.e., "never or sometimes used") or used consistently ("used most or all CI, 1.065-2.704]; P=0.026) while health-care assistants were more likely to be asymptomatic ( 

The comparison in high-risk procedures and infection protective measures between asymptomatic 163 HCWs and symptomatic HCWs are shown in Table 3 . No significant differences were seen in any 164 high-risk procedures between asymptomatic HCWs and symptomatic HCWs. Compared with 165 symptomatic HCWs, asymptomatic HCWs more consistently used hand washing, isolation gown, eye 166 protection, N95 respirators, gloves, and hair cover for protection (P<0.001).

We also analyzed the factors associated with asymptomatic infection among HCWs by using logistic 168 regression model. The univariable logistic regression analysis showed worked in high-risk departments, 169 hand washing consistently and consistent use of isolation gown, N95 respirators, gloves, hair cover, 170 and eye protection were associated with an increased likelihood of asymptomatic infection (Table S1) .

However, evidences about the differences between symptomatic and asymptomatic individuals with to be associated with an increased likelihood of symptomatic SARS-CoV-2 infection, while consistent 184 use of N95 respirators and eye protection tended to be asymptomatic infection. All these findings 185 suggested a potential relationship between initial infectious dose and disease severity. 

Masks Do More Than Protect Others During COVID-19: 286 Reducing the Inoculum of SARS-CoV-2 to Protect the Wearer

Covid-19: four fifths of cases are asymptomatic, China figures indicate

Estimating the asymptomatic proportion of coronavirus 291 disease 2019 (COVID-19) cases on board the Diamond Princess cruise ship

Estimation of the asymptomatic ratio of novel coronavirus 294 infections (COVID-19)

Screening of Healthcare Workers for SARS-CoV-2 Highlights 296 the Role of Asymptomatic Carriage in COVID-19 Transmission

Development and validation of a risk factor-based system to 299 predict short-term survival in adult hospitalized patients with COVID-19: a multicenter, retrospective, 300 cohort study

Factors associated with hospital admission and critical illness

We thank all the HCWs fighting COVID-19 in the front-line. They are putting