key: cord-0799191-ezw0721e
authors: Passarelli, Victor C.; Faico-Filho, Klinger; Moreira, Luiz Vinicius Leão; Cunha, Ana Paula; Carvalho, Joseane Mayara Almeida; Barbosa, Gabriela Rodrigues; Camargo, Clarice; Conte, Danielle D.; Perosa, Ana H.; Bellei, Nancy
title: Asymptomatic COVID-19 in hospital visitors: underestimated potential of viral shedding
date: 2020-10-28
journal: Int J Infect Dis
DOI: 10.1016/j.ijid.2020.10.057
sha: 5a377f127586a0289f1d3d7a17b7ff906cf9e386
doc_id: 799191
cord_uid: ezw0721e

In one day, 6 in 150 (4%) asymptomatic visitors were diagnosed with COVID-19 at a hospital with universal masking policy. Two inpatients (contacts) subsequentely developed symptoms. More rigorous protective measures during visitation periods may need to be included in infection control practices in order to reduce nosocomial transmissions.

Data were summarized as percentages and medians (ranges); 95% confidence intervals were calculated via the binomial method using Free Statistics Software (version 4.0).

One hundred and fifty asymptomatic visitors were screened for COVID-19. There was close contact between them before and during hospitalization.

One possibility is that transmission happened beforehand, since longer incubation periods and transmission from asymptomatic individuals have been reported (1).

Although it is not possible to completely exclude transmissions related to other patients or hospital staff (1) (2) (3) (4) , no other contacts developed symptoms before or afterwards.

Healthcare-related outbreaks of COVID-19 have been reported (2,3) mostly when institutions had not implemented adequate infection control measures (5) . A recent large US study showed a low incidence of hospital-acquired COVID-19 (5). However, J o u r n a l P r e -p r o o f nosocomial infections still occur, and may be closely related to asymptomatic and presymptomatic individuals' potential of transmission (4) .

While implementation of universal masking does reduce transmissions (4-6), they might also induce a false perception of protection that could lead to neglect of other important protective measures (6) . The risk of SARS-CoV-2 introduction into facilities by visitors increases as community transmission is widespread (7), therefore occurrence of outbreaks could be mitigated with restriction of time and physical contact during visitation periods, and reassurance of adequate and frequent hand hygiene, as well as personal protective equipment, when necessary. Besides, active screening for visitors might need to be considered as part of infection control protocols (7).

In summary, surveillance of asymptomatic visitors with a rigorous implementation of protective measures during visitation periods may need to be included in infection control practices in order to reduce transmissions in healthcare settings.

This work received support from the Brazilian Coordination for the Improvement of Higher Education Personnel (CAPES) and the National Council 

The incidence of the novel coronavirus SARS-CoV-2 among asymptomatic patients: a systematic review

Public Health-Seattle and King County and CDC COVID-19 Investigation Team. Presymptomatic SARS-CoV-2 Infections and Transmission in a Skilled Nursing Facility

Outbreak investigation of COVID-19 among residents and staff of an independent and assisted living community for older adults in

Asymptomatic SARS-CoV-2 infections in hospitalized patients

Incidence of Nosocomial COVID-19 in Patients Hospitalized at a Large US Academic Medical Center

Face Masks Against COVID-19: An Evidence Review

Management of Visitors to Healthcare Facilities in the Context of COVID-19: Non-US Healthcare Settings

Centers for Disease Control and Prevention. CDC 2019-Novel Coronavirus (2019-nCoV) Real-Time RT-PCR Diagnostic Panel

Sensitivity of different RT-qPCR solutions for SARS-CoV-2 detection

All authors approve the final version of this manuscript.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.J o u r n a l P r e -p r o o f