Infectivity peaks early in COVID-19 patients, emphasizing the need for rapid isolation of cases: study

SARS-CoV-2 genetic material can be detected in respiratory or stool samples for several weeks, but is alive in samples collected more than 9 days after the onset of symptoms and in people with SARS-CoV. No virus (which can cause infection) was found. -2 is likely to be highly infectious from the onset of symptoms and the next 5 days, according to a systematic review and meta-analysis of three human coronaviruses. Lancet microorganisms journal.

“This is the first systematic review and meta-analysis that has been comprehensively investigated and compared. Viral load It then sheds these three human coronaviruses. This clearly explains why SARS-CoV-2 spreads more efficiently than SARS-CoV and MERS-CoV and is so difficult to contain, “said Dr. Dr., the lead author of the University of St Andrews, UK. Muge Cevik says.

“Our findings are consistent with contact tracing studies that suggest that most viral infection events occur very early, especially within the first 5 days after the onset of symptoms, and symptoms begin. It demonstrates the importance of self-isolation immediately after infection. General about the range of disease-related symptoms, including mild symptoms that may occur early in the infection rather than more prominent symptoms such as cough and fever Recognition. “

Since this study specifically targeted people infected with SARS-CoV-2 and those who were primarily hospitalized, the results are only relevant to the period of self-isolation of people with confirmed COVID-19 and may be quarantined. Does not apply to people. Alternatively, it may not have been exposed after contact with an infected person. Currently, many countries recommend that SARS-CoV-2 infected individuals be self-quarantined for 10 days. This carefully covers the duration of infection and is consistent with the findings, the authors say.

Understanding when a patient is most likely to become infected is very important to inform effective public health measures to control the spread of SARS-CoV-2. This study looked at important factors related to this.Viral load (viral load) Virus Infection changes the body), release of viral RNA (the length of time someone releases the virus) Genetic material (RNA), which does not necessarily indicate that a person is infected (because it cannot necessarily replicate), and isolation of a living virus (living virus is isolated and tested). A stronger indicator of human infectivity to see if it is present) can be successfully replicated in the laboratory).

The researchers included 98 studies, cohort studies, and randomized controlled trials with 5 or more participants. 79 focused on SARS-CoV-2, 73 of which included inpatients only. 8 people at SARS-CoV. 11 for MERS-CoV infection. From these studies, the authors calculated the average length of viral RNA release to determine changes in viral load and whether they succeeded in isolating live virus from the various samples collected throughout the infection. ..

Analyzing the results of the SARS-CoV-2 study, the average time that viral RNA is released is Upper respiratory tractThe lower airway, stool and serum were 17 days, 14.6 days, 17.2 days and 16.6 days, respectively. The longest duration of RNA release was 83, 59, 35 and 60 days, respectively.

Of the 11 studies that attempted to isolate live virus, all studies using respiratory samples included successful culture of viable virus within the first week of illness. Among the studies that also measured RNA viral load, these showed an association between successful isolation of live virus and viral load levels. The studies included in this systematic review failed to successfully isolate live virus after day 9 of symptoms in any type of sample, despite persistently high viral RNA loading.So far, live viruses Stool sample Despite long-term RNA release, the role of SARS-CoV-2 in oral fecal infection remains unclear.

“These findings suggest that in clinical practice, it may not be necessary to repeat the PCR test to consider the patient to be no longer infectious. This remains positive for much longer, not necessarily others. It does not indicate that the person may be infected with the virus. For non-severe symptoms, the duration of infection can be counted as 10 days instead. Symptoms Onset, “says Dr. Sevic.

The maximum viral load of SARS-CoV-2 RNA was detected early in the disease at the onset of symptoms or 5 days before symptoms. In contrast, viral load 8 and MERS-CoV peaked after 10-14 days and 7-10 days. SymptomsExplain why each person can effectively reduce the transmission of these viruses by immediately identifying, quarantining, and quarantining people who are symptomatic of the disease.

Only 12 studies have been reported on asymptomatic individuals infected with SARS-CoV-2, 6 of which also looked at how quickly people cleared the viral substance from their bodies.

“The load of viral RNA looks about the same between people with and without symptoms, but some studies show that asymptomatic people may get rid of viral substances from the body faster. Has been suggested, “said Dr. Cevik. “Several studies have shown that asymptomatic infected individuals can clear the virus faster, and asymptomatic individuals may be as infectious as those with symptoms at the onset of infection. However, at this stage, limited data are available to inform changes in the quarantine period policy in the absence of testing regarding the elimination of infectious virus in asymptomatic individuals. It has been. “

This is the most comprehensive study of these three respiratory coronaviruses to date and is larger than previous meta-analyses of SARS-CoV-2, but the authors note some limitations. I will.Many of the patients throughout the various studies included in Systematic review The meta-analysis was hospitalized and received a variety of treatments that could affect the process of infection. The study included different populations with different tracking and management and included in the interpretation of statistics used to measure the length of viral shedding. The duration of infection may not exactly match the success of culturing live virus from the sample, but these can be widespread overlaps.

“Most of the studies included in our review were conducted in hospitalized patients, so our findings may not apply to milder people. infection These results suggest that people with mild cases may remove the virus from their bodies faster. In addition, increased deployment of treatments such as dexamethasone, remdecibyl, and other antiviral and immunomodulatory drugs in clinical trials may affect virus shedding in hospitalized patients. Further research on virus shedding in this context is needed, “said Dr. Antonia Ho, MRC of the Center for Virus Research, University of Glasgow, UK.