Duration of quarantine in hospitalized patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection: a question needing an answer

Abstract

In December 2019 a new form of pneumonia was observed in the Chinese province of Hubei.[1] The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was subsequently identified as responsible of this condition, defined coronavirus disease (COVID-19).[2] The virus has now spread outside Chinese borders with 82,297 cases and 2,804 deaths worldwide at the 26th of February.[3] After infection, symptoms appear after an incubation time of 3-5 days, with 80% of those infected developing a mild disease, 15% a severe disease and 5% will require support in intensive care unit (ICU).[4] Overall, the estimated case-fatality rate is comprised between 0.4% and 2.9% and the basic reproduction number is approximately 3.28.[4,5] SARS-CoV-2 is a new pathogen for humankind and any type of immune protection exist, thus everybody can be potentially infected. Moreover, no primary prophylaxis measures (vaccination) nor effective treatments are available. If the above represented percentages are applied to the worldwide populations, it appears clear why any measure should be considered to avoid a further diffusion of the virus and prevent the saturation and collapse of health systems and the most catastrophic pandemic since 1919 Spanish flu. Isolation of those affected and the use of personal protective equipment (PPE) are the mainstay to block transmission of this pathogen, which is presumed through respiratory droplets. A 14 days quarantine is applied to subjects coming from endemic areas or who had contact with confirmed cases. It is assumed that, if in this period the subject does not develop any sign or symptoms compatible with COVID-19, he is not infected and thus the quarantine can be removed, and the subject returned to the community. Domiciliary quarantine of 14 days since a positive test is applied also for patients with a diagnosed mild disease who did not need medical support. These rules are effective in controlling infections in the community, but several doubts arise when it is necessary to transpose them in the hospital setting. Hospitals are indeed a delicate place in epidemics: they collect fragile persons who can be exposed to the virus and are subsequently readmitted to the community thus spreading the infection. Indeed, the ongoing outbreak in Northern Italy has been linked to a single infected patient who accessed to a community hospital where he transmitted the virus to several other patients and health-care operators.[6] Moreover, the isolation of patients in the hospital setting impose a significant burden in terms of PPE used by the health-care operators, space dedicated and time employed in their management. Even more complex is the situation of patients in ICU, where viral spreading is facilitated by endotracheal tubes and manoeuvres performed on the respiratory tract. Therefore, a clear definition of the infectiousness timing and intensity of viral spreading is mandatory to alleviate the burden on the health-care system. Unfortunately, the data available on the topic are scarce and composed only of measurements of viral shedding, without an assessment of the infectivity. Kim et al.[7] assessed the viral load kinetics of SARS-CoV-2 in upper and lower respiratory tract materials in the first two confirmed patients in Korea. They employed real-time reverse transcriptase polymerase chain reaction (rRT-PCR) to detect SARS-CoV-2 and converted cycle threshold (CT) values of rRT-PCR into RNA copy number. The detection limit of rRT-PCR was 2,690 copies/mL. Overall, viral load above detection limit was detected until 14 and 25 days after symptoms onset and for 13 and 11 days after the first detection, respectively.[7] Of note, both patients received treatment with lopinavir/ritonavir. Instead, Zou and colleagues analysed viral load in repeated nasal and throat swabs obtained from the 17 symptomatic patients.[8] They also employed rRT-PCR and considered a CT of 40 as detection limit. Higher viral loads were observed in nasal swabs and in samples collected soon after symptoms onset. Overall, only two patients presented positive samples, and only in nasal swab, 14 days after symptoms onset, and with low viral load. In conclusion, a larger amount of data about duration of viral spreading and infectivity in hospitalized patients, especially in ICU, is badly needed to better define quarantine period and avoid nosocomial transmission. Before their availability, the canonical 14 days period of quarantine should be respected. Financial support none related to the content of this manuscript. Conflict of interests none related to the content of this manuscript.