The peak of infection in Covid-19, that is the time when the level of contagion is highest, happens in the first five days after the onset of symptoms, according to a new British study, published in the journal ‘The Lancet’ and cited by ‘Euronews’.
The research, according to its authors, underlines the need to identify and isolate cases of COVID-19 earlier, so that transmission is reduced to the maximum. Understanding when patients are most infectious has become of critical importance to publicize effective public health measures to control the spread of the virus.
«This is the first systematic review and meta-analysis that comprehensively analyzed and compared viral load and the elimination of these three human coronaviruses, giving a clear explanation of why SARS-CoV-2 spreads more efficiently than than others and is much more difficult to contain, ”said Muge Cevik, from the University of St Andrews in Scotland, the study’s lead author.
The expert reveals that these findings «are in line with contact screening studies that suggest that most viral transmission events occur very early, and especially in the first five days after the onset of symptoms, stressing the importance of self-isolation immediately that period ‘.
The review, one of the most comprehensive to date with 98 studies included, looked at three human coronaviruses – SARS-CoV, SARS-CoV-2 and MERS-CoV – and their viral loads. Of the three, COVID-19 was considered the most likely to be highly infectious in the first five days after the onset of symptoms.
Although the genetic material of the virus was still detected in respiratory samples, the researchers found no live virus in any sample taken from patients after nine days of infection, according to the research.
There were, however, some limitations to the research, the authors noted, including the fact that many of the patients in the study had been hospitalized and received a variety of treatments that were likely to impact the rate of infection.
«Most of the studies included in our review were performed on patients who were admitted to the hospital. Therefore, the results may not apply to people with milder infection, although they suggest that those with less severity may clear the virus from their bodies faster, “said Antonia Ho, co-author of the research.
In addition, he added, “the increasing implementation of treatments, such as dexamethasone, remdesivir and other antivirals in clinical trials, are likely to influence viral elimination in hospitalized patients. Further studies on viral elimination are needed in this context ».