Coronavirus: Asymptomatic people have the same viral load as those who show symptoms

A new study shows that coronavirus positive patients without symptoms have viral RNA levels similar to those who are symptomatic. The Jama Internal Medicine study

(photo: Christian Ender / Getty Images). In the nose, throat and lungs of asymptomatic patients there is a viral load similar to patients who instead show the typical symptoms of the new coronavirus infection. This was suggested by a new study carried out by researchers from Soonchunhyang University (South Korea), which provides further evidence to support the idea that even asymptomatics could spread Sars-Cov-2. The results, published in the journal Jama Internal Medicine, thus return to fuel the heated debate on how contagious patients positive for the new coronavirus are actually, without symptoms.

Since the beginning of the pandemic, in fact, science is trying to understand the mysterious role of asymptomatics in the transmission of Covid-19. According to the World Health Organization (WHO) and the Higher Institute of Health (ISS), getting infected with people without symptoms is a "rare" or "very rare" eventuality and is not among the main routes of contagion of the new coronavirus . Among the reasons is that the virus is transmitted through the famous droplets of infected saliva, and therefore those who have no symptoms, such as cough, are less likely to send their viral particles to those in the immediate vicinity. But scientists immediately expressed perplexity: according to some, contagion from asymptomatic patients is possible and not at all rare. For example, as we had told you, the virologist of the University of Padua Andrea Crisanti, referring to the study of the municipality of Vo 'Euganeo, said that 43% of people positive for coronavirus were asymptomatic and contagious as those who showed symptoms.

In the new study, the team of researchers analysed with the technique of real-time Pcr swabs collected between the 6th and the 26th of march last by 303 people , aged between 22 and 36 years, put in isolation in Cheonan, a city of South Korea. Of the total, 193 were symptomatic and 110 were asymptomatic and, among those who were initially asymptomatic , 89 patients, about 30% of the total, has never developed symptoms (so it would be more correct to call the remaining patients presintomatici ). From the subsequent analysis, the researchers found that people without symptoms were both in the upper airway, lower levels of viral load high, and similar to people with the symptoms. Not only that, on average, asymptomatic, presented the negativity of the buffer earlier than the symptomatic, respectively, of 17 to 19.5 days.

However, as pointed out by the same researchers, the study has analysed only the genetic material of the coronavirus (the viral rna) present in patients and has not demonstrated how the patients were actually infectious. The question of what role is played in the spread of Covid-19 , then, is still open and will still have a lot of data and evidence to arrive at a definitive conclusion. “Although the high viral load that we observed in asymptomatic patients poses a clear risk of transmission, our study was not designed to prove it,” explain the researchers in the study. “It is important to note, in fact, that the identification of the viral rna is not equivalent to the presence and transmission of infective virus. For a better understanding on the potential transmissibility of asymptomatic infection are necessary, extensive, and rigorous epidemiological and experimental studies”. But in the meantime, suggests the team, “the isolation of asymptomatic patients is necessary to control the spread of the new coronavirus”.