A new study has confirmed that those infected with the coronavirus who do not show the clinical signs of Covid-19 are almost as dangerous to healthy people as other patients.
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A team of American scientists from the Broad Institute analyzed the viral load in hospitalized patients with Covid-19, as well as in asymptomatic carriers of the coronavirus. Results of work published on the preprint site medRxiv.org (the study has not yet been reviewed).
One of the main problems of the Covid-19 pandemic is the huge number of asymptomatic patients. The spread of SARS-CoV-2 in people who do not show clinical signs of infection makes it difficult for the healthcare system to fight the coronavirus disease and make timely diagnoses.
Until now, the distribution of viral load (a measure of the severity of an infection that is calculated by assessing the number of viral particles in a given volume of body fluid of an infected organism) in symptomatic and non-symptomatic people has remained uncertain. Meanwhile, this is what will help to fully assess the risks of transmission of the virus.
The new study was conducted with the participation of residents and staff of most nursing homes and some similar institutions in Massachusetts. “From April 9 to June 9, 2020, we tested nasopharyngeal swabs from 32,480 people. <…> In addition, we extracted RNA and tested it for SARS-CoV-2 by reverse transcription polymerase chain reaction. <…> A total of 2,654 nursing home residents (15.5%) and 624 employees (4.1%) tested positive for SARS-CoV-2. SARS-CoV-2 was detected in 12.7% of residents and 3.7% of staff without symptoms, compared with 53.1% of residents and 18.2% of staff with symptoms, ”the authors write.
According to the large-scale analysis, the scientists report that patients with symptoms or without them who were tested, found “remarkably similar distributions of viral load.” Moreover, the similarities were most noticeable precisely during the peak of the epidemic in Massachusetts.
“Collectively, the distribution of viral load was very similar, with statistically but not significantly different mean, between symptomatic and symptomatic populations over time, across all subcategories studied (age, race, ethnicity, gender, resident / staff ). The averages were indistinguishable between these groups during the peak of the outbreak in Massachusetts, but the gap appeared later, during the survey period towards the end of May, when the epidemic began to subside, ”the scientists note.
In their opinion, since the distribution of the viral load in infected people, regardless of symptoms, is similar, the existing RNA testing methods, which have been confirmed to detect SARS-CoV-2 in patients with clinical signs of Covid-19, should also work for those who are on at first glance it seems healthy. Finally, the findings of the new work confirm that asymptomatic carriers are dangerous to healthy people almost as much as everyone else infected with the coronavirus.
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