Time Length of Negativization and Cycle Threshold Values in 182 Healthcare Workers with Covid-19 in Milan, Italy: An Observational Cohort Study

Lisa Cariani, Beatrice Silvia Orena, Federico Ambrogi, Simone Gambazza, Anna Maraschini, Antonella Dodaro, Massimo Oggioni, Annarosa Orlandi, Alessia Pirrone, Sara Uceda Renteria, Mara Bernazzani, Anna Paola Cantù, Ferruccio Ceriotti and Giovanna Lunghi
Additional contact information
Lisa Cariani: Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Microbiology Unit, 20122 Milan, Italy
Beatrice Silvia Orena: Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Microbiology Unit, 20122 Milan, Italy
Federico Ambrogi: Laboratory of Medical Statistics and Biometry, Giulio A. Maccacaro, Department of Clinical Sciences and Community Health, Campus Cascina Rosa, University of Milan, 20133 Milan, Italy
Simone Gambazza: Laboratory of Medical Statistics and Biometry, Giulio A. Maccacaro, Department of Clinical Sciences and Community Health, Campus Cascina Rosa, University of Milan, 20133 Milan, Italy
Anna Maraschini: Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Microbiology Unit, 20122 Milan, Italy
Antonella Dodaro: Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Microbiology Unit, 20122 Milan, Italy
Massimo Oggioni: Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Virology Unit, 20122 Milan, Italy
Annarosa Orlandi: Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Virology Unit, 20122 Milan, Italy
Alessia Pirrone: Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Microbiology Unit, 20122 Milan, Italy
Sara Uceda Renteria: Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Virology Unit, 20122 Milan, Italy
Mara Bernazzani: Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Responsabile Infermieristico area Direzione Medica di Presidio, Coordinamento dipartimenti clinici, Servizio Prevenzione Igiene Ospedaliera, 20122 Milan, Italy
Anna Paola Cantù: Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Direzione Medica di Presidio, 20122 Milan, Italy
Ferruccio Ceriotti: Fondazione IRCCS Ca’ Granda Ospedale Maggiore, Clinical Laboratory, 20122 Milan, Italy
Giovanna Lunghi: Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Virology Unit, 20122 Milan, Italy

IJERPH, 2020, vol. 17, issue 15, 1-10

Abstract: Background : Coronavirus Disease 2019 (COVID-19) has rapidly spread worldwide, becoming an unprecedented public health emergency. Rapid detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) suspected cases is crucial to control the spread of infection. We aimed to evaluate the time length of negativization from the onset of symptoms in healthcare workers (HCWs) with COVID-19, and to evaluate significant variations in cycle threshold (CT) values and gene positivity (E, RdRP, and N genes) among positive individuals who returned to work. Methods : We retrospectively analyzed a consecutive cohort of 182 SARS-CoV-2-positive HCWs in Milan, from 16 March to 30 April 2020. Nasopharyngeal swabs were tested by RT-PCR. Results : Asymptomatic HCWs were 17.6% (32/182), and 58 healed at 30 April 2020. The median time length of negativization was 4 weeks (35% of symptomatic versus 40% of asymptomatic HCWs). Four HCWs, healed at 30 April, turned positive within three weeks during controls set up in the work unit. Three-gene positivity had the greatest variability, and increasing CT values from single- to three-gene positivity among all age groups were observed. Conclusions : Self-isolation longer than two weeks and prolonged follow-up periods for the staff returning to work after COVID-19 could be the most suitable choices to counter the SARS-CoV-2 spread. Further studies are needed to investigate infectiousness profiles among positive individuals.

Keywords: SARS-CoV-2; Coronavirus Disease 2019; Reverse Transcription PCR; Cycle Threshold values; health care workers (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2020
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