Abstract:Background
Long-term shedding of viral RNA in COVID-19 prevents timely discharge from the hospital or de-escalation of infection prevention and control practices. Key questions are the duration and determinants of infectious virus shedding. We assessed these questions using virus cultures of respiratory tract samples from hospitalized COVID-19 patients as a proxy for infectious virus shedding.
Methods
Clinical and virological data were obtained from 129 hospitalized COVID-19 patients (89 intensive care, 40 med… Show more
“…where the probability to detect infectious virus dropped below 5% at day 15 post symptoms onset 26 . By characterizing the course of infectious virus, we predicted the generation time which indicates the speed at which the infection spreads in the population, to be about 4 days (CI 95% = [2.8-7.6]).…”
Non-human primates infected with SARS-CoV-2 exhibit mild clinical signs. Here we used a mathematical model to characterize in detail the viral dynamics in 31 cynomolgus macaques infected with 106 pfu of SARS-CoV-2 for which nasopharyngeal and tracheal viral load were frequently assessed. We identified that infected cells had a large daily viral production (>104 virus) and a within-host reproductive basic number of 6 and 4 in nasopharyngeal and tracheal compartment, respectively. After peak viral load, infected cells were rapidly cleared with a half-life of 9 hours, with no significant association between cytokine elevation and clearance. Translating our model to the context of human-to-human infection, human mild infection may be characterized by a peak occurring 4 days after infection, a viral shedding of ~11 days and a generation time of 4 days. These results improve the understanding of SARS-CoV-2 viral replication and better understand the infection to SARS-CoV-2 in humans.
“…where the probability to detect infectious virus dropped below 5% at day 15 post symptoms onset 26 . By characterizing the course of infectious virus, we predicted the generation time which indicates the speed at which the infection spreads in the population, to be about 4 days (CI 95% = [2.8-7.6]).…”
Non-human primates infected with SARS-CoV-2 exhibit mild clinical signs. Here we used a mathematical model to characterize in detail the viral dynamics in 31 cynomolgus macaques infected with 106 pfu of SARS-CoV-2 for which nasopharyngeal and tracheal viral load were frequently assessed. We identified that infected cells had a large daily viral production (>104 virus) and a within-host reproductive basic number of 6 and 4 in nasopharyngeal and tracheal compartment, respectively. After peak viral load, infected cells were rapidly cleared with a half-life of 9 hours, with no significant association between cytokine elevation and clearance. Translating our model to the context of human-to-human infection, human mild infection may be characterized by a peak occurring 4 days after infection, a viral shedding of ~11 days and a generation time of 4 days. These results improve the understanding of SARS-CoV-2 viral replication and better understand the infection to SARS-CoV-2 in humans.
“…The updated criteria for discharge from isolation balances risks and benefits. These recommendations are based on findings of neutralizing antibodies 5–10 days after infection with SARS-CoV-2 and that binding of these neutralizing antibodies to the virus is expected to reduce the risk of virus transmission [ 21 ].…”
The diffusion of SARS-CoV-2, starting from China in December 2019, has led to a pandemic, reaching Italy in February 2020. Previous studies in Asia have shown that the median duration of SARS-CoV-2 viral shedding was approximately 12–20 days. We considered a cohort of patients recovered from COVID-19 showing that the median disease duration between onset and end of COVID-19 symptoms was 27.5 days (interquartile range (IQR): 17.0–33.2) and that the median duration between onset of symptoms and microbiological healing, defined by two consecutive negative nasopharyngeal swabs, was 38 days (IQR: 31.7–50.2). A longer duration of COVID-19 with delayed clinical healing (symptom-free) occurred in patients presenting at admission a lower PaO2/FiO2 ratio (p < 0.001), a more severe clinical presentation (p = 0.001) and a lower lymphocyte count (p = 0.035). Moreover, patients presenting at admission a lower PaO2/FiO2 ratio and more severe disease showed longer viral shedding (p = 0.031 and p = 0.032, respectively). In addition, patients treated with corticosteroids had delayed clinical healing (p = 0.013).
Purpose
The European Geriatric Medicine Society (EuGMS) is launching a second interim guidance whose aim is to prevent the entrance and spread of COVID-19 into long-term care facilities (LTCFs).
Methods
The EuGMS gathered experts to propose a guide of measures to prevent COVID-19 outbreaks in LTCFs. It is based on the specific features of SARS-CoV-2 transmission in LTCFs, residents’ needs, and on experiences conducted in the field.
Results
Asymptomatic COVID-19 residents and staff members contribute substantially to the dissemination of COVID-19 infection in LTCFs. An infection prevention and control focal point should be set up in every LTCF for (1) supervising infection prevention and control measures aimed at keeping COVID-19 out of LTCFs, (2) RT-PCR testing of residents, staff members, and visitors with COVID-19 symptoms, even atypical, and (3) isolating subjects either infected or in contact with infected subjects. When a first LCTF resident or staff member is infected, a facility-wide RT-PCR test–retest strategy should be implemented for detecting all SARS-CoV-2 carriers. Testing should continue until no new COVID-19 cases are identified. The isolation of residents should be limited as much as possible and associated with measures aiming at limiting its negative effects on their mental and somatic health status.
Conclusions
An early recognition of symptoms compatible with COVID-19 may help to diagnose COVID-19 residents and staff more promptly. Subsequently, an earlier testing for SARS-CoV-2 symptomatic and asymptomatic LTCF staff and residents will enable the implementation of appropriate infection prevention and control. The negative effects of social isolation in residents should be limited as much as possible.
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