Only a few months ago we have known about SARS-CoV-2, the new coronavirus that has unleashed an unprecedented global crisis in recent years. For this reason, it is necessary to grasp each piece of information, each conclusion and each study that is published in this regard. It will take us months, even years, to really know all the details related to the new COVID-19 disease: how it is spread, how it is transmitted, if it mutates a lot or a little, if it generates immunity and for how long … In the meantime, we must take into account Note that these are all preliminary conclusions and that it is normal for the information we receive to change almost from one day to the next.
On April 1, China began publishing the detected cases of people infected with coronavirus who do not have symptoms. Detecting them is essential to stop the advance of the pandemic and also to prevent second waves from returning in countries that seem to have already emerged from the first outbreak , as is the case in the Asian country. In the opinion of experts, if these symptom-free people, as well as their contacts, are isolated for 14 days, a second wave of the epidemic is highly unlikely.
The problem is that the data we have on asymptomatic infection by the new coronavirus is scarce and confusing. In China, a new outbreak is feared from imported cases, and because of this, people who come from abroad are being tested very rigorously. The National Health Commission reported that, in the 24 hours prior to the afternoon of April 1, 166 new cases of infection had been detected, and that 130 of them were asymptomatic, that is: 78%.
“The sample is very small and more cases will be available soon. In addition, we do not know exactly how they were identified either, but in any case, let’s say that they are generalizable. And even that they have a 10% error, even so, this means that the virus is already everywhere ”, says the epidemiologist and honorary researcher of the Center for Evidence-Based Medicine at the University of Oxford Tom Jefferson in an interview the medical journal BJM. For this scientist, it is very likely that the virus has been circulating among us for much longer than previously thought, so that large sectors of the population would have already been exposed.
The experience of a small Italian town
In mid-February, a small town of 3,000 inhabitants located 50 kilometers from Venice was completely isolated by the Italian authorities and the entire population began to be tested. Sergio Romagnani, a researcher at the University of Florence, followed this whole process and found that the vast majority of detected cases (between 50 and 75%) were asymptomatic , but represented an important source of contagion. Within 10 days of starting to isolate all the people who tested positive, the number of people affected by COVID-19 in the town fell by 90%.
The case of Iceland
Another good place to look for preliminary data that reports on the problem of asymptomatic infections is Iceland, a country that is testing for SARS-CoV-19 to anyone who wants it in order to locate how many more cases the better to be able to isolate them. and prevent the spread of the virus.
To date, slightly more than 5% of the population has been subjected to the test and, according to the data published by the authorities, it seems that around half of the cases detected would be carrying the infection without showing symptoms.
